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1 <feed xmlns="http://www.w3.org/2005/Atom" xml:lang="en">
2 <title>nLab</title>
3 <link rel="alternate" type="application/xhtml+xml" href="https://ncatl…
4 <link rel="self" href="https://ncatlab.org/nlab/atom_with_content"/>
5 <updated>2021-07-02T09:22:44Z</updated>
6 <id>tag:ncatlab.org,2008-11-28:nLab</id>
7 <subtitle>An Instiki Wiki</subtitle>
8 <generator uri="http://golem.ph.utexas.edu/instiki/show/HomePage" vers…
9 <entry>
10 <title type="html">Urs Frauenfelder</title>
11 <link rel="alternate" type="application/xhtml+xml" href="https://nca…
12 <updated>2021-07-02T09:22:44Z</updated>
13 <published>2021-07-02T09:22:46Z</published>
14 <id>tag:ncatlab.org,2021-07-02:nLab,Urs+Frauenfelder</id>
15 <author>
16 <name>Urs Schreiber</name>
17 </author>
18 <content type="xhtml" xml:base="https://ncatlab.org/nlab/show/Urs+Fr…
19 <div xmlns="http://www.w3.org/1999/xhtml">
20 <ul>
21 <li>
22 <p><a href='https://www.uni-augsburg.de/en/fakultaet/mntf/math/prof/geom…
23 </li>
24
25 <li>
26 <p><a href='https://www.genealogy.math.ndsu.nodak.edu/id.php?id=120240'>…
27 </li>
28 </ul>
29
30 <h2 id='selected_writings'>Selected writings</h2>
31
32 <p>On <a class='existingWikiWord' href='/nlab/show/cyclic+loop+space'>cy…
33
34 <ul>
35 <li><a class='existingWikiWord' href='/nlab/show/Urs+Frauenfelder'>Urs F…
36 </ul>
37
38 <p><div class='property'> category: <a class='category_link' href='/nlab…
39 </content>
40 </entry>
41 <entry>
42 <title type="html">cyclic loop space</title>
43 <link rel="alternate" type="application/xhtml+xml" href="https://nca…
44 <updated>2021-07-02T09:20:18Z</updated>
45 <published>2017-02-14T09:56:17Z</published>
46 <id>tag:ncatlab.org,2017-02-14:nLab,cyclic+loop+space</id>
47 <author>
48 <name>Urs Schreiber</name>
49 </author>
50 <content type="xhtml" xml:base="https://ncatlab.org/nlab/show/cyclic…
51 <div xmlns="http://www.w3.org/1999/xhtml">
52 <div class='rightHandSide'>
53 <div class='toc clickDown' tabindex='0'>
54 <h3 id='context'>Context</h3>
55
56 <h4 id='topology'>Topology</h4>
57
58 <div class='hide'>
59 <p><strong><a class='existingWikiWord' href='/nlab/show/topology'>topolo…
60
61 <p>see also <em><a class='existingWikiWord' href='/nlab/show/differentia…
62
63 <p><a class='existingWikiWord' href='/nlab/show/Introduction+to+Topology…
64
65 <p><strong>Basic concepts</strong></p>
66
67 <ul>
68 <li>
69 <p><a class='existingWikiWord' href='/nlab/show/open+subspace'>open subs…
70 </li>
71
72 <li>
73 <p><a class='existingWikiWord' href='/nlab/show/topological+space'>topol…
74 </li>
75
76 <li>
77 <p><a class='existingWikiWord' href='/nlab/show/topological+base'>base f…
78 </li>
79
80 <li>
81 <p><a class='existingWikiWord' href='/nlab/show/finer+topology'>finer/co…
82 </li>
83
84 <li>
85 <p><a class='existingWikiWord' href='/nlab/show/closed+subspace'>closure…
86 </li>
87
88 <li>
89 <p><a class='existingWikiWord' href='/nlab/show/separation+axioms'>separ…
90 </li>
91
92 <li>
93 <p><a class='existingWikiWord' href='/nlab/show/continuous+map'>continuo…
94 </li>
95
96 <li>
97 <p><a class='existingWikiWord' href='/nlab/show/uniformly+continuous+map…
98 </li>
99
100 <li>
101 <p><a class='existingWikiWord' href='/nlab/show/embedding+of+topological…
102 </li>
103
104 <li>
105 <p><a class='existingWikiWord' href='/nlab/show/open+map'>open map</a>, …
106 </li>
107
108 <li>
109 <p><a class='existingWikiWord' href='/nlab/show/sequence'>sequence</a>, …
110 </li>
111
112 <li>
113 <p><a class='existingWikiWord' href='/nlab/show/convergence'>convergence…
114 </li>
115
116 <li>
117 <p><a class='existingWikiWord' href='/nlab/show/category'>category</a> <…
118
119 <ul>
120 <li><a class='existingWikiWord' href='/nlab/show/convenient+category+of+…
121 </ul>
122 </li>
123 </ul>
124
125 <p><strong><a href='Top#UniversalConstructions'>Universal constructions<…
126
127 <ul>
128 <li>
129 <p><a class='existingWikiWord' href='/nlab/show/weak+topology'>initial t…
130 </li>
131
132 <li>
133 <p><a class='existingWikiWord' href='/nlab/show/subspace'>subspace</a>, …
134 </li>
135
136 <li>
137 <p>fiber space, <a class='existingWikiWord' href='/nlab/show/space+attac…
138 </li>
139
140 <li>
141 <p><a class='existingWikiWord' href='/nlab/show/product+topological+spac…
142 </li>
143
144 <li>
145 <p><a class='existingWikiWord' href='/nlab/show/mapping+cylinder'>mappin…
146 </li>
147
148 <li>
149 <p><a class='existingWikiWord' href='/nlab/show/mapping+cone'>mapping co…
150 </li>
151
152 <li>
153 <p><a class='existingWikiWord' href='/nlab/show/mapping+telescope'>mappi…
154 </li>
155
156 <li>
157 <p><a class='existingWikiWord' href='/nlab/show/colimits+of+normal+space…
158 </li>
159 </ul>
160
161 <p><strong><a class='existingWikiWord' href='/nlab/show/stuff%2C+structu…
162
163 <ul>
164 <li>
165 <p><a class='existingWikiWord' href='/nlab/show/nice+topological+space'>…
166 </li>
167
168 <li>
169 <p><a class='existingWikiWord' href='/nlab/show/metric+space'>metric spa…
170 </li>
171
172 <li>
173 <p><a class='existingWikiWord' href='/nlab/show/Kolmogorov+topological+s…
174 </li>
175
176 <li>
177 <p><a class='existingWikiWord' href='/nlab/show/sober+topological+space'…
178 </li>
179
180 <li>
181 <p><a class='existingWikiWord' href='/nlab/show/compact+space'>compact s…
182
183 <p><a class='existingWikiWord' href='/nlab/show/sequentially+compact+top…
184 </li>
185
186 <li>
187 <p><a class='existingWikiWord' href='/nlab/show/compactly+generated+topo…
188 </li>
189
190 <li>
191 <p><a class='existingWikiWord' href='/nlab/show/second-countable+space'>…
192 </li>
193
194 <li>
195 <p><a class='existingWikiWord' href='/nlab/show/contractible+space'>cont…
196 </li>
197
198 <li>
199 <p><a class='existingWikiWord' href='/nlab/show/connected+space'>connect…
200 </li>
201
202 <li>
203 <p><a class='existingWikiWord' href='/nlab/show/simply+connected+space'>…
204 </li>
205
206 <li>
207 <p><a class='existingWikiWord' href='/nlab/show/cell+complex'>cell compl…
208 </li>
209
210 <li>
211 <p><a class='existingWikiWord' href='/nlab/show/pointed+topological+spac…
212 </li>
213
214 <li>
215 <p><a class='existingWikiWord' href='/nlab/show/topological+vector+space…
216 </li>
217
218 <li>
219 <p><a class='existingWikiWord' href='/nlab/show/topological+group'>topol…
220 </li>
221
222 <li>
223 <p><a class='existingWikiWord' href='/nlab/show/topological+vector+bundl…
224 </li>
225
226 <li>
227 <p><a class='existingWikiWord' href='/nlab/show/topological+manifold'>to…
228 </li>
229 </ul>
230
231 <p><strong>Examples</strong></p>
232
233 <ul>
234 <li>
235 <p><a class='existingWikiWord' href='/nlab/show/empty+space'>empty space…
236 </li>
237
238 <li>
239 <p><a class='existingWikiWord' href='/nlab/show/discrete+object'>discret…
240 </li>
241
242 <li>
243 <p><a class='existingWikiWord' href='/nlab/show/Sierpinski+space'>Sierpi…
244 </li>
245
246 <li>
247 <p><a class='existingWikiWord' href='/nlab/show/order+topology'>order to…
248 </li>
249
250 <li>
251 <p><a class='existingWikiWord' href='/nlab/show/Euclidean+space'>Euclide…
252
253 <ul>
254 <li><a class='existingWikiWord' href='/nlab/show/real+number'>real line<…
255 </ul>
256 </li>
257
258 <li>
259 <p><a class='existingWikiWord' href='/nlab/show/cylinder+object'>cylinde…
260 </li>
261
262 <li>
263 <p><a class='existingWikiWord' href='/nlab/show/sphere'>sphere</a>, <a c…
264 </li>
265
266 <li>
267 <p><a class='existingWikiWord' href='/nlab/show/circle'>circle</a>, <a c…
268 </li>
269
270 <li>
271 <p><a class='existingWikiWord' href='/nlab/show/polytope'>polytope</a>, …
272 </li>
273
274 <li>
275 <p><a class='existingWikiWord' href='/nlab/show/projective+space'>projec…
276 </li>
277
278 <li>
279 <p><a class='existingWikiWord' href='/nlab/show/classifying+space'>class…
280 </li>
281
282 <li>
283 <p><a class='existingWikiWord' href='/nlab/show/configuration+space+of+p…
284 </li>
285
286 <li>
287 <p><a class='existingWikiWord' href='/nlab/show/path'>path</a>, <a class…
288 </li>
289
290 <li>
291 <p><a class='existingWikiWord' href='/nlab/show/compact-open+topology'>m…
292
293 <ul>
294 <li><a class='existingWikiWord' href='/nlab/show/loop+space'>loop space<…
295 </ul>
296 </li>
297
298 <li>
299 <p><a class='existingWikiWord' href='/nlab/show/Zariski+topology'>Zarisk…
300 </li>
301
302 <li>
303 <p><a class='existingWikiWord' href='/nlab/show/Cantor+space'>Cantor spa…
304 </li>
305
306 <li>
307 <p><a class='existingWikiWord' href='/nlab/show/Peano+curve'>Peano curve…
308 </li>
309
310 <li>
311 <p><a class='existingWikiWord' href='/nlab/show/line+with+two+origins'>l…
312 </li>
313
314 <li>
315 <p><a class='existingWikiWord' href='/nlab/show/K-topology'>K-topology</…
316 </li>
317
318 <li>
319 <p><a class='existingWikiWord' href='/nlab/show/Warsaw+circle'>Warsaw ci…
320 </li>
321 </ul>
322
323 <p><strong>Basic statements</strong></p>
324
325 <ul>
326 <li>
327 <p><a class='existingWikiWord' href='/nlab/show/Hausdorff+implies+sober'…
328 </li>
329
330 <li>
331 <p><a class='existingWikiWord' href='/nlab/show/schemes+are+sober'>schem…
332 </li>
333
334 <li>
335 <p><a class='existingWikiWord' href='/nlab/show/continuous+images+of+com…
336 </li>
337
338 <li>
339 <p><a class='existingWikiWord' href='/nlab/show/closed+subspaces+of+comp…
340 </li>
341
342 <li>
343 <p><a class='existingWikiWord' href='/nlab/show/open+subspaces+of+compac…
344 </li>
345
346 <li>
347 <p><a class='existingWikiWord' href='/nlab/show/quotient+projections+out…
348 </li>
349
350 <li>
351 <p><a class='existingWikiWord' href='/nlab/show/compact+spaces+equivalen…
352
353 <ul>
354 <li>
355 <p><a class='existingWikiWord' href='/nlab/show/Lebesgue+number+lemma'>L…
356 </li>
357
358 <li>
359 <p><a class='existingWikiWord' href='/nlab/show/sequentially+compact+met…
360 </li>
361
362 <li>
363 <p><a class='existingWikiWord' href='/nlab/show/compact+spaces+equivalen…
364 </li>
365
366 <li>
367 <p><a class='existingWikiWord' href='/nlab/show/sequentially+compact+met…
368 </li>
369 </ul>
370 </li>
371
372 <li>
373 <p><a class='existingWikiWord' href='/nlab/show/continuous+metric+space+…
374 </li>
375
376 <li>
377 <p><a class='existingWikiWord' href='/nlab/show/paracompact+Hausdorff+sp…
378 </li>
379
380 <li>
381 <p><a class='existingWikiWord' href='/nlab/show/paracompact+Hausdorff+sp…
382 </li>
383
384 <li>
385 <p><a class='existingWikiWord' href='/nlab/show/closed+injections+are+em…
386 </li>
387
388 <li>
389 <p><a class='existingWikiWord' href='/nlab/show/proper+maps+to+locally+c…
390 </li>
391
392 <li>
393 <p><a class='existingWikiWord' href='/nlab/show/injective+proper+maps+to…
394 </li>
395
396 <li>
397 <p><a class='existingWikiWord' href='/nlab/show/locally+compact+and+sigm…
398 </li>
399
400 <li>
401 <p><a class='existingWikiWord' href='/nlab/show/locally+compact+and+seco…
402 </li>
403
404 <li>
405 <p><a class='existingWikiWord' href='/nlab/show/second-countable+regular…
406 </li>
407
408 <li>
409 <p><a class='existingWikiWord' href='/nlab/show/CW-complexes+are+paracom…
410 </li>
411 </ul>
412
413 <p><strong>Theorems</strong></p>
414
415 <ul>
416 <li>
417 <p><a class='existingWikiWord' href='/nlab/show/Urysohn%27s+lemma'>Uryso…
418 </li>
419
420 <li>
421 <p><a class='existingWikiWord' href='/nlab/show/Tietze+extension+theorem…
422 </li>
423
424 <li>
425 <p><a class='existingWikiWord' href='/nlab/show/Tychonoff+theorem'>Tycho…
426 </li>
427
428 <li>
429 <p><a class='existingWikiWord' href='/nlab/show/tube+lemma'>tube lemma</…
430 </li>
431
432 <li>
433 <p><a class='existingWikiWord' href='/nlab/show/Michael%27s+theorem'>Mic…
434 </li>
435
436 <li>
437 <p><a class='existingWikiWord' href='/nlab/show/Brouwer%27s+fixed+point+…
438 </li>
439
440 <li>
441 <p><a class='existingWikiWord' href='/nlab/show/topological+invariance+o…
442 </li>
443
444 <li>
445 <p><a class='existingWikiWord' href='/nlab/show/Jordan+curve+theorem'>Jo…
446 </li>
447 </ul>
448
449 <p><strong>Analysis Theorems</strong></p>
450
451 <ul>
452 <li>
453 <p><a class='existingWikiWord' href='/nlab/show/Heine-Borel+theorem'>Hei…
454 </li>
455
456 <li>
457 <p><a class='existingWikiWord' href='/nlab/show/intermediate+value+theor…
458 </li>
459
460 <li>
461 <p><a class='existingWikiWord' href='/nlab/show/extreme+value+theorem'>e…
462 </li>
463 </ul>
464
465 <p><strong><a class='existingWikiWord' href='/nlab/show/topological+homo…
466
467 <ul>
468 <li>
469 <p><a class='existingWikiWord' href='/nlab/show/homotopy'>left homotopy<…
470 </li>
471
472 <li>
473 <p><a class='existingWikiWord' href='/nlab/show/homotopy+equivalence'>ho…
474 </li>
475
476 <li>
477 <p><a class='existingWikiWord' href='/nlab/show/fundamental+group'>funda…
478 </li>
479
480 <li>
481 <p><a class='existingWikiWord' href='/nlab/show/fundamental+theorem+of+c…
482 </li>
483
484 <li>
485 <p><a class='existingWikiWord' href='/nlab/show/homotopy+group'>homotopy…
486 </li>
487
488 <li>
489 <p><a class='existingWikiWord' href='/nlab/show/weak+homotopy+equivalenc…
490 </li>
491
492 <li>
493 <p><a class='existingWikiWord' href='/nlab/show/Whitehead+theorem'>White…
494 </li>
495
496 <li>
497 <p><a class='existingWikiWord' href='/nlab/show/Freudenthal+suspension+t…
498 </li>
499
500 <li>
501 <p><a class='existingWikiWord' href='/nlab/show/nerve+theorem'>nerve the…
502 </li>
503
504 <li>
505 <p><a class='existingWikiWord' href='/nlab/show/homotopy+extension+prope…
506 </li>
507
508 <li>
509 <p><a class='existingWikiWord' href='/nlab/show/topological+cofiber+sequ…
510 </li>
511
512 <li>
513 <p><a class='existingWikiWord' href='/nlab/show/Str%C3%B8m+model+structu…
514 </li>
515
516 <li>
517 <p><a class='existingWikiWord' href='/nlab/show/classical+model+structur…
518 </li>
519 </ul>
520 </div>
521
522 <h4 id='homotopy_theory'>Homotopy theory</h4>
523
524 <div class='hide'>
525 <p><strong><a class='existingWikiWord' href='/nlab/show/homotopy+theory'…
526
527 <p>flavors: <a class='existingWikiWord' href='/nlab/show/stable+homotopy…
528
529 <p>models: <a class='existingWikiWord' href='/nlab/show/topological+homo…
530
531 <p>see also <strong><a class='existingWikiWord' href='/nlab/show/algebra…
532
533 <p><strong>Introductions</strong></p>
534
535 <ul>
536 <li>
537 <p><a class='existingWikiWord' href='/nlab/show/Introduction+to+Topology…
538 </li>
539
540 <li>
541 <p><a class='existingWikiWord' href='/nlab/show/Introduction+to+Homotopy…
542 </li>
543
544 <li>
545 <p><a class='existingWikiWord' href='/nlab/show/geometry+of+physics+--+h…
546 </li>
547 </ul>
548
549 <p><strong>Definitions</strong></p>
550
551 <ul>
552 <li>
553 <p><a class='existingWikiWord' href='/nlab/show/homotopy'>homotopy</a>, …
554 </li>
555
556 <li>
557 <p><a class='existingWikiWord' href='/nlab/show/homotopy+type'>homotopy …
558 </li>
559
560 <li>
561 <p><a class='existingWikiWord' href='/nlab/show/Pi-algebra'>Pi-algebra</…
562 </li>
563
564 <li>
565 <p><a class='existingWikiWord' href='/nlab/show/homotopy+coherent+catego…
566
567 <ul>
568 <li>
569 <p><a class='existingWikiWord' href='/nlab/show/homotopical+category'>ho…
570
571 <ul>
572 <li>
573 <p><a class='existingWikiWord' href='/nlab/show/model+category'>model ca…
574 </li>
575
576 <li>
577 <p><a class='existingWikiWord' href='/nlab/show/category+of+fibrant+obje…
578 </li>
579
580 <li>
581 <p><a class='existingWikiWord' href='/nlab/show/Waldhausen+category'>Wal…
582 </li>
583 </ul>
584 </li>
585
586 <li>
587 <p><a class='existingWikiWord' href='/nlab/show/homotopy+category'>homot…
588
589 <ul>
590 <li><a class='existingWikiWord' href='/nlab/show/Ho%28Top%29'>Ho(Top)</a…
591 </ul>
592 </li>
593 </ul>
594 </li>
595
596 <li>
597 <p><a class='existingWikiWord' href='/nlab/show/%28infinity%2C1%29-categ…
598
599 <ul>
600 <li><a class='existingWikiWord' href='/nlab/show/homotopy+category+of+an…
601 </ul>
602 </li>
603 </ul>
604
605 <p><strong>Paths and cylinders</strong></p>
606
607 <ul>
608 <li>
609 <p><a class='existingWikiWord' href='/nlab/show/homotopy'>left homotopy<…
610
611 <ul>
612 <li>
613 <p><a class='existingWikiWord' href='/nlab/show/cylinder+object'>cylinde…
614 </li>
615
616 <li>
617 <p><a class='existingWikiWord' href='/nlab/show/mapping+cone'>mapping co…
618 </li>
619 </ul>
620 </li>
621
622 <li>
623 <p><a class='existingWikiWord' href='/nlab/show/homotopy'>right homotopy…
624
625 <ul>
626 <li>
627 <p><a class='existingWikiWord' href='/nlab/show/path+space+object'>path …
628 </li>
629
630 <li>
631 <p><a class='existingWikiWord' href='/nlab/show/mapping+cocone'>mapping …
632 </li>
633
634 <li>
635 <p><a class='existingWikiWord' href='/nlab/show/generalized+universal+bu…
636 </li>
637 </ul>
638 </li>
639
640 <li>
641 <p><a class='existingWikiWord' href='/nlab/show/interval+object'>interva…
642
643 <ul>
644 <li>
645 <p><a class='existingWikiWord' href='/nlab/show/localization+at+geometri…
646 </li>
647
648 <li>
649 <p><a class='existingWikiWord' href='/nlab/show/infinitesimal+interval+o…
650 </li>
651 </ul>
652 </li>
653 </ul>
654
655 <p><strong>Homotopy groups</strong></p>
656
657 <ul>
658 <li>
659 <p><a class='existingWikiWord' href='/nlab/show/homotopy+group'>homotopy…
660
661 <ul>
662 <li>
663 <p><a class='existingWikiWord' href='/nlab/show/fundamental+group'>funda…
664
665 <ul>
666 <li><a class='existingWikiWord' href='/nlab/show/fundamental+group+of+a+…
667 </ul>
668 </li>
669
670 <li>
671 <p><a class='existingWikiWord' href='/nlab/show/Brown-Grossman+homotopy+…
672 </li>
673
674 <li>
675 <p><a class='existingWikiWord' href='/nlab/show/categorical+homotopy+gro…
676 </li>
677
678 <li>
679 <p><a class='existingWikiWord' href='/nlab/show/geometric+homotopy+group…
680 </li>
681 </ul>
682 </li>
683
684 <li>
685 <p><a class='existingWikiWord' href='/nlab/show/fundamental+infinity-gro…
686
687 <ul>
688 <li>
689 <p><a class='existingWikiWord' href='/nlab/show/fundamental+groupoid'>fu…
690
691 <ul>
692 <li><a class='existingWikiWord' href='/nlab/show/path+groupoid'>path gro…
693 </ul>
694 </li>
695
696 <li>
697 <p><a class='existingWikiWord' href='/nlab/show/fundamental+infinity-gro…
698 </li>
699
700 <li>
701 <p><a class='existingWikiWord' href='/nlab/show/fundamental+infinity-gro…
702 </li>
703 </ul>
704 </li>
705
706 <li>
707 <p><a class='existingWikiWord' href='/nlab/show/fundamental+%28infinity%…
708
709 <ul>
710 <li><a class='existingWikiWord' href='/nlab/show/fundamental+category'>f…
711 </ul>
712 </li>
713 </ul>
714
715 <p><strong>Basic facts</strong></p>
716
717 <ul>
718 <li><a class='existingWikiWord' href='/nlab/show/fundamental+group+of+th…
719 </ul>
720
721 <p><strong>Theorems</strong></p>
722
723 <ul>
724 <li>
725 <p><a class='existingWikiWord' href='/nlab/show/fundamental+theorem+of+c…
726 </li>
727
728 <li>
729 <p><a class='existingWikiWord' href='/nlab/show/Freudenthal+suspension+t…
730 </li>
731
732 <li>
733 <p><a class='existingWikiWord' href='/nlab/show/Blakers-Massey+theorem'>…
734 </li>
735
736 <li>
737 <p><a class='existingWikiWord' href='/nlab/show/higher+homotopy+van+Kamp…
738 </li>
739
740 <li>
741 <p><a class='existingWikiWord' href='/nlab/show/nerve+theorem'>nerve the…
742 </li>
743
744 <li>
745 <p><a class='existingWikiWord' href='/nlab/show/Whitehead+theorem'>White…
746 </li>
747
748 <li>
749 <p><a class='existingWikiWord' href='/nlab/show/Hurewicz+theorem'>Hurewi…
750 </li>
751
752 <li>
753 <p><a class='existingWikiWord' href='/nlab/show/Galois+theory'>Galois th…
754 </li>
755
756 <li>
757 <p><a class='existingWikiWord' href='/nlab/show/homotopy+hypothesis'>hom…
758 </li>
759 </ul>
760 </div>
761 </div>
762 </div>
763
764 <h1 id='contents'>Contents</h1>
765 <div class='maruku_toc'><ul><li><a href='#idea'>Idea</a></li><li><a href…
766 <h2 id='idea'>Idea</h2>
767
768 <p>Any <a class='existingWikiWord' href='/nlab/show/free+loop+space'>fre…
769
770 <p>If <math class='maruku-mathml' display='inline' id='mathml_1b9519ae4b…
771
772 <p>If <math class='maruku-mathml' display='inline' id='mathml_1b9519ae4b…
773
774 <h2 id='properties'>Properties</h2>
775
776 <h3 id='AsRightBaseChange'>As right base change along <math class='maruk…
777
778 <p>The cyclic loop space <math class='maruku-mathml' display='inline' id…
779
780 <h3 id='ordinary_cohomology_of__on_cyclic_cohomology_of_'>Ordinary cohom…
781
782 <p>Let <math class='maruku-mathml' display='inline' id='mathml_1b9519ae4…
783
784 <p>The <a class='existingWikiWord' href='/nlab/show/ordinary+cohomology'…
785 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
786 H^\bullet(\mathcal{L}X)
787 \simeq
788 HH_\bullet( C^\bullet(X) )
789 \,.
790
791 </annotation></semantics></math></div>
792 <p>Moreover the <math class='maruku-mathml' display='inline' id='mathml_…
793 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
794 H^\bullet(\mathcal{L}X \sslash S^1)
795 \simeq
796 HC_\bullet( C^\bullet(X) )
797
798 </annotation></semantics></math></div>
799 <p>(<a href='#Jones87'>Jones 87, Thm. A</a>, review in <a href='#Loday92…
800
801 <p>If the <a class='existingWikiWord' href='/nlab/show/coefficient'>coef…
802
803 <p>In the special case that the <a class='existingWikiWord' href='/nlab/…
804 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
805 H^\bullet(\mathcal{L}X)
806 \simeq
807 HH_\bullet( \Omega^\bullet(X) )
808 \,.
809
810 </annotation></semantics></math></div><div class='maruku-equation'><math…
811 H^\bullet(\mathcal{L}X \sslash S^1)
812 \simeq
813 HC_\bullet( \Omega^\bullet(X) )
814 \,.
815
816 </annotation></semantics></math></div>
817 <p>This is known as <em><a class='existingWikiWord' href='/nlab/show/Jon…
818
819 <p>An <a class='existingWikiWord' href='/nlab/show/%28infinity%2C1%29-ca…
820
821 <h3 id='rational_sullivan_model'>Rational Sullivan model</h3>
822
823 <p>See at <em><a class='existingWikiWord' href='/nlab/show/Sullivan+mode…
824
825 <h2 id='related_concepts'>Related concepts</h2>
826
827 <ul>
828 <li>
829 <p><a class='existingWikiWord' href='/nlab/show/double+dimensional+reduc…
830 </li>
831
832 <li>
833 <p><a class='existingWikiWord' href='/nlab/show/cyclic+loop+stack'>cycli…
834 </li>
835
836 <li>
837 <p><a class='existingWikiWord' href='/nlab/show/free+loop+space'>free lo…
838 </li>
839 </ul>
840
841 <h2 id='references'>References</h2>
842
843 <p>The notion of the cyclic loop space of a topological space appears as…
844
845 <ul>
846 <li id='Jones87'>
847 <p><a class='existingWikiWord' href='/nlab/show/John+David+Stuart+Jones'…
848 </li>
849
850 <li>
851 <p><a class='existingWikiWord' href='/nlab/show/Gunnar+Carlsson'>Gunnar …
852 </li>
853
854 <li id='Witten88'>
855 <p><a class='existingWikiWord' href='/nlab/show/Edward+Witten'>Edward Wi…
856 </li>
857
858 <li id='Loday92'>
859 <p><a class='existingWikiWord' href='/nlab/show/Jean-Louis+Loday'>Jean-L…
860
861 <p>Chapter 7 in: <em>Cyclic Homology</em>, Grundlehren <strong>301</stro…
862 </li>
863
864 <li id='Loday11'>
865 <p><a class='existingWikiWord' href='/nlab/show/Jean-Louis+Loday'>Jean-L…
866 </li>
867
868 <li id='Stapleton11'>
869 <p><a class='existingWikiWord' href='/nlab/show/Nathaniel+Stapleton'>Nat…
870 </li>
871 </ul>
872
873 <p>Specifically on cyclic loop spaces of <a class='existingWikiWord' hre…
874
875 <ul>
876 <li><a class='existingWikiWord' href='/nlab/show/Nancy+Hingston'>Nancy H…
877 </ul>
878
879 <p>See also:</p>
880
881 <ul>
882 <li><a class='existingWikiWord' href='/nlab/show/Urs+Frauenfelder'>Urs F…
883 </ul>
884
885 <p>A version of the cyclic loop space of <a class='existingWikiWord' hre…
886
887 <ul>
888 <li id='Huan18'><a class='existingWikiWord' href='/nlab/show/Zhen+Huan'>…
889 </ul>
890
891 <p>following</p>
892
893 <ul>
894 <li><a class='existingWikiWord' href='/nlab/show/Zhen+Huan'>Zhen Huan</a…
895 </ul>
896
897 <p>and recalled/expanded on in several followup articles, such as in</p>
898
899 <ul>
900 <li><a class='existingWikiWord' href='/nlab/show/Zhen+Huan'>Zhen Huan</a…
901 </ul>
902
903 <p>The above formulation of cyclic loop spaces, in the generality of <a …
904
905 <ul>
906 <li id='BMSS19'><a class='existingWikiWord' href='/nlab/show/Vincent+Bra…
907 </ul>
908
909 <p>following the analogous discussion in <a class='existingWikiWord' hre…
910
911 <ul>
912 <li id='FSS18'><a class='existingWikiWord' href='/nlab/show/Domenico+Fio…
913 </ul>
914
915 <p>with exposition in</p>
916
917 <ul>
918 <li><a class='existingWikiWord' href='/nlab/show/Urs+Schreiber'>Urs Schr…
919 </ul>
920
921 <p>
922 </p>
923
924 <p>
925
926 </p> </div>
927 </content>
928 </entry>
929 <entry>
930 <title type="html">Nancy Hingston</title>
931 <link rel="alternate" type="application/xhtml+xml" href="https://nca…
932 <updated>2021-07-02T09:15:40Z</updated>
933 <published>2021-07-02T09:14:11Z</published>
934 <id>tag:ncatlab.org,2021-07-02:nLab,Nancy+Hingston</id>
935 <author>
936 <name>Urs Schreiber</name>
937 </author>
938 <content type="xhtml" xml:base="https://ncatlab.org/nlab/show/Nancy+…
939 <div xmlns="http://www.w3.org/1999/xhtml">
940 <ul>
941 <li>
942 <p><a href='https://en.wikipedia.org/wiki/Nancy_Hingston'>Wikipedia entr…
943 </li>
944
945 <li>
946 <p><a href='https://science.tcnj.edu/school-information/women-in-science…
947 </li>
948
949 <li>
950 <p><a href='https://science.tcnj.edu/school-information/women-in-science…
951 </li>
952 </ul>
953
954 <h2 id='selected_writings'>Selected writings</h2>
955
956 <p>On the <a class='existingWikiWord' href='/nlab/show/cyclic+loop+space…
957
958 <ul>
959 <li><a class='existingWikiWord' href='/nlab/show/Nancy+Hingston'>Nancy H…
960 </ul>
961
962 <p><div class='property'> category: <a class='category_link' href='/nlab…
963 </content>
964 </entry>
965 <entry>
966 <title type="html">Ralph Cohen</title>
967 <link rel="alternate" type="application/xhtml+xml" href="https://nca…
968 <updated>2021-07-02T08:58:22Z</updated>
969 <published>2010-11-26T21:46:21Z</published>
970 <id>tag:ncatlab.org,2010-11-26:nLab,Ralph+Cohen</id>
971 <author>
972 <name>Urs Schreiber</name>
973 </author>
974 <content type="xhtml" xml:base="https://ncatlab.org/nlab/show/Ralph+…
975 <div xmlns="http://www.w3.org/1999/xhtml">
976 <ul>
977 <li><a href='http://math.stanford.edu/~ralph/'>website</a></li>
978 </ul>
979
980 <h2 id='selected_writings'>Selected writings</h2>
981
982 <p>On <a class='existingWikiWord' href='/nlab/show/cyclic+loop+space'>cy…
983
984 <ul>
985 <li><a class='existingWikiWord' href='/nlab/show/Gunnar+Carlsson'>Gunnar…
986 </ul>
987
988 <p>On <a class='existingWikiWord' href='/nlab/show/string+topology'>stri…
989
990 <ul>
991 <li>
992 <p><a class='existingWikiWord' href='/nlab/show/Ralph+Cohen'>Ralph Cohen…
993 </li>
994
995 <li>
996 <p><a class='existingWikiWord' href='/nlab/show/Ralph+Cohen'>Ralph Cohen…
997 </li>
998
999 <li id='CohenJones'>
1000 <p><a class='existingWikiWord' href='/nlab/show/Ralph+Cohen'>Ralph Cohen…
1001 </li>
1002
1003 <li id='CohenGodin03'>
1004 <p><a class='existingWikiWord' href='/nlab/show/Ralph+Cohen'>Ralph Cohen…
1005 </li>
1006
1007 <li>
1008 <p><a class='existingWikiWord' href='/nlab/show/Ralph+Cohen'>Ralph Cohen…
1009 </li>
1010
1011 <li>
1012 <p><a class='existingWikiWord' href='/nlab/show/Ralph+Cohen'>Ralph Cohen…
1013 </li>
1014 </ul>
1015
1016 <p>On <a class='existingWikiWord' href='/nlab/show/moduli+space+of+monop…
1017
1018 <ul>
1019 <li>
1020 <p><a class='existingWikiWord' href='/nlab/show/Fred+Cohen'>Fred Cohen</…
1021 </li>
1022
1023 <li>
1024 <p><a class='existingWikiWord' href='/nlab/show/Ralph+Cohen'>Ralph Cohen…
1025 </li>
1026 </ul>
1027
1028 <p>and more generally on <a class='existingWikiWord' href='/nlab/show/mo…
1029
1030 <ul>
1031 <li><a class='existingWikiWord' href='/nlab/show/Ralph+Cohen'>Ralph Cohe…
1032 </ul>
1033
1034 <p><div class='property'> category: <a class='category_link' href='/nlab…
1035 </content>
1036 </entry>
1037 <entry>
1038 <title type="html">Gunnar Carlsson</title>
1039 <link rel="alternate" type="application/xhtml+xml" href="https://nca…
1040 <updated>2021-07-02T08:57:51Z</updated>
1041 <published>2014-04-13T09:19:17Z</published>
1042 <id>tag:ncatlab.org,2014-04-13:nLab,Gunnar+Carlsson</id>
1043 <author>
1044 <name>Urs Schreiber</name>
1045 </author>
1046 <content type="xhtml" xml:base="https://ncatlab.org/nlab/show/Gunnar…
1047 <div xmlns="http://www.w3.org/1999/xhtml">
1048 <ul>
1049 <li><a href='http://math.stanford.edu/~gunnar/'>webpage</a></li>
1050 </ul>
1051
1052 <h2 id='selected_writings'>Selected writings</h2>
1053
1054 <p>On <a class='existingWikiWord' href='/nlab/show/cyclic+loop+space'>cy…
1055
1056 <ul>
1057 <li><a class='existingWikiWord' href='/nlab/show/Gunnar+Carlsson'>Gunnar…
1058 </ul>
1059
1060 <p>On <a class='existingWikiWord' href='/nlab/show/topological+data+anal…
1061
1062 <ul>
1063 <li><a class='existingWikiWord' href='/nlab/show/Gunnar+Carlsson'>Gunnar…
1064 </ul>
1065
1066 <p>On <a class='existingWikiWord' href='/nlab/show/persistent+homology'>…
1067
1068 <ul>
1069 <li>
1070 <p>A. Zomorodian, <a class='existingWikiWord' href='/nlab/show/Gunnar+Ca…
1071 </li>
1072
1073 <li>
1074 <p><a class='existingWikiWord' href='/nlab/show/Gunnar+Carlsson'>Gunnar …
1075 </li>
1076
1077 <li>
1078 <p><a class='existingWikiWord' href='/nlab/show/Gunnar+Carlsson'>Gunnar …
1079 </li>
1080 </ul>
1081
1082 <h2 id='related_lab_entries'>Related <math class='maruku-mathml' display…
1083
1084 <ul>
1085 <li>
1086 <p><a class='existingWikiWord' href='/nlab/show/equivariant+stable+homot…
1087 </li>
1088
1089 <li>
1090 <p><a class='existingWikiWord' href='/nlab/show/Segal-Carlsson+completio…
1091
1092 <p><a class='existingWikiWord' href='/nlab/show/Burnside+ring'>Burnside …
1093 </li>
1094
1095 <li>
1096 <p><a class='existingWikiWord' href='/nlab/show/persistent+homology'>per…
1097 </li>
1098 </ul>
1099
1100 <p><div class='property'> category: <a class='category_link' href='/nlab…
1101
1102 <p>
1103 </p> </div>
1104 </content>
1105 </entry>
1106 <entry>
1107 <title type="html">Doug Ravenel</title>
1108 <link rel="alternate" type="application/xhtml+xml" href="https://nca…
1109 <updated>2021-07-02T08:31:03Z</updated>
1110 <published>2012-08-14T17:36:28Z</published>
1111 <id>tag:ncatlab.org,2012-08-14:nLab,Doug+Ravenel</id>
1112 <author>
1113 <name>Urs Schreiber</name>
1114 </author>
1115 <content type="xhtml" xml:base="https://ncatlab.org/nlab/show/Doug+R…
1116 <div xmlns="http://www.w3.org/1999/xhtml">
1117 <ul>
1118 <li>
1119 <p><a href='http://www.math.rochester.edu/people/faculty/doug/'>webpage<…
1120 </li>
1121
1122 <li>
1123 <p><a class='existingWikiWord' href='/nlab/show/Michael+Hopkins'>Michael…
1124 </li>
1125 </ul>
1126
1127 <h2 id='selected_writings'>Selected writings</h2>
1128
1129 <p>On the <a class='existingWikiWord' href='/nlab/show/Hopf+algebra'>Hop…
1130
1131 <ul>
1132 <li><a class='existingWikiWord' href='/nlab/show/Doug+Ravenel'>Douglas R…
1133 </ul>
1134
1135 <p>On the <a class='existingWikiWord' href='/nlab/show/Adams%E2%80%93Nov…
1136
1137 <ul>
1138 <li id='Ravenel78'><a class='existingWikiWord' href='/nlab/show/Doug+Rav…
1139 </ul>
1140
1141 <p>On <a class='existingWikiWord' href='/nlab/show/chromatic+homotopy+th…
1142
1143 <ul>
1144 <li id='Ravenel84'><a class='existingWikiWord' href='/nlab/show/Doug+Rav…
1145 </ul>
1146
1147 <p>On <a class='existingWikiWord' href='/nlab/show/homotopy+groups+of+sp…
1148
1149 <ul>
1150 <li id='MahowaldRavenel87'><a class='existingWikiWord' href='/nlab/show/…
1151 </ul>
1152
1153 <p>On <a class='existingWikiWord' href='/nlab/show/elliptic+genus'>ellip…
1154
1155 <ul>
1156 <li id='LandweberRavenelStong93'><a class='existingWikiWord' href='/nlab…
1157 </ul>
1158
1159 <p>On <a class='existingWikiWord' href='/nlab/show/chromatic+homotopy+th…
1160
1161 <ul>
1162 <li><a class='existingWikiWord' href='/nlab/show/Doug+Ravenel'>Doug Rave…
1163 </ul>
1164
1165 <p>On <a class='existingWikiWord' href='/nlab/show/iterated+loop+space'>…
1166
1167 <ul>
1168 <li><a class='existingWikiWord' href='/nlab/show/Doug+Ravenel'>Douglas R…
1169 </ul>
1170
1171 <p><div class='property'> category: <a class='category_link' href='/nlab…
1172
1173 <p>
1174 </p> </div>
1175 </content>
1176 </entry>
1177 <entry>
1178 <title type="html">stable splitting of mapping spaces</title>
1179 <link rel="alternate" type="application/xhtml+xml" href="https://nca…
1180 <updated>2021-07-02T08:30:06Z</updated>
1181 <published>2018-10-28T12:06:36Z</published>
1182 <id>tag:ncatlab.org,2018-10-28:nLab,stable+splitting+of+mapping+spac…
1183 <author>
1184 <name>Urs Schreiber</name>
1185 </author>
1186 <content type="xhtml" xml:base="https://ncatlab.org/nlab/show/stable…
1187 <div xmlns="http://www.w3.org/1999/xhtml">
1188 <div class='rightHandSide'>
1189 <div class='toc clickDown' tabindex='0'>
1190 <h3 id='context'>Context</h3>
1191
1192 <h4 id='stable_homotopy_theory'>Stable Homotopy theory</h4>
1193
1194 <div class='hide'>
1195 <p><strong><a class='existingWikiWord' href='/nlab/show/stable+homotopy+…
1196
1197 <ul>
1198 <li><a class='existingWikiWord' href='/nlab/show/homological+algebra'>ho…
1199 </ul>
1200
1201 <p><em><a class='existingWikiWord' href='/nlab/show/Introduction+to+Stab…
1202
1203 <h1 id='ingredients'>Ingredients</h1>
1204
1205 <ul>
1206 <li><a class='existingWikiWord' href='/nlab/show/homotopy+theory'>homoto…
1207 </ul>
1208
1209 <h1 id='contents'>Contents</h1>
1210
1211 <ul>
1212 <li>
1213 <p><a class='existingWikiWord' href='/nlab/show/loop+space+object'>loop …
1214 </li>
1215
1216 <li>
1217 <p><a class='existingWikiWord' href='/nlab/show/suspension+object'>suspe…
1218 </li>
1219
1220 <li>
1221 <p><a class='existingWikiWord' href='/nlab/show/looping'>looping and del…
1222 </li>
1223
1224 <li>
1225 <p><a class='existingWikiWord' href='/nlab/show/stable+%28infinity%2C1%2…
1226
1227 <ul>
1228 <li>
1229 <p><a class='existingWikiWord' href='/nlab/show/stabilization'>stabiliza…
1230
1231 <ul>
1232 <li><a class='existingWikiWord' href='/nlab/show/spectrum+object'>spectr…
1233 </ul>
1234 </li>
1235
1236 <li>
1237 <p><a class='existingWikiWord' href='/nlab/show/stable+derivator'>stable…
1238 </li>
1239
1240 <li>
1241 <p><a class='existingWikiWord' href='/nlab/show/triangulated+category'>t…
1242 </li>
1243 </ul>
1244 </li>
1245
1246 <li>
1247 <p><a class='existingWikiWord' href='/nlab/show/stable+%28infinity%2C1%2…
1248
1249 <ul>
1250 <li>
1251 <p><a class='existingWikiWord' href='/nlab/show/spectrum'>spectrum</a></…
1252 </li>
1253
1254 <li>
1255 <p><a class='existingWikiWord' href='/nlab/show/stable+homotopy+category…
1256 </li>
1257 </ul>
1258 </li>
1259
1260 <li>
1261 <p><a class='existingWikiWord' href='/nlab/show/smash+product+of+spectra…
1262
1263 <ul>
1264 <li>
1265 <p><a class='existingWikiWord' href='/nlab/show/symmetric+smash+product+…
1266 </li>
1267
1268 <li>
1269 <p><a class='existingWikiWord' href='/nlab/show/Spanier-Whitehead+dualit…
1270 </li>
1271
1272 <li>
1273 <p><a class='existingWikiWord' href='/nlab/show/A-infinity-ring'>A-∞ r…
1274 </li>
1275
1276 <li>
1277 <p><a class='existingWikiWord' href='/nlab/show/E-infinity-ring'>E-∞ r…
1278 </li>
1279 </ul>
1280 </li>
1281 </ul>
1282 <div>
1283 <p>
1284 <a href='/nlab/edit/stable+homotopy+theory+-+contents'>Edit this sideb…
1285 </p>
1286 </div></div>
1287
1288 <h4 id='goodwillie_calculus'>Goodwillie calculus</h4>
1289
1290 <div class='hide'>
1291 <p><strong><a class='existingWikiWord' href='/nlab/show/Goodwillie+calcu…
1292
1293 <ul>
1294 <li>
1295 <p><a class='existingWikiWord' href='/nlab/show/Goodwillie-differentiabl…
1296 </li>
1297
1298 <li>
1299 <p><a class='existingWikiWord' href='/nlab/show/excisive+%28%E2%88%9E%2C…
1300
1301 <ul>
1302 <li>
1303 <p><a class='existingWikiWord' href='/nlab/show/spectrum+object'>spectru…
1304 </li>
1305
1306 <li>
1307 <p><a class='existingWikiWord' href='/nlab/show/tangent+%28infinity%2C1%…
1308 </li>
1309 </ul>
1310 </li>
1311
1312 <li>
1313 <p><a class='existingWikiWord' href='/nlab/show/n-excisive+%28%E2%88%9E%…
1314
1315 <ul>
1316 <li>
1317 <p><a class='existingWikiWord' href='/nlab/show/jet+%28infinity%2C1%29-c…
1318 </li>
1319
1320 <li>
1321 <p><a class='existingWikiWord' href='/nlab/show/polynomial+%28%E2%88%9E%…
1322 </li>
1323 </ul>
1324 </li>
1325
1326 <li>
1327 <p><a class='existingWikiWord' href='/nlab/show/Goodwillie-Taylor+tower'…
1328
1329 <ul>
1330 <li>
1331 <p><a class='existingWikiWord' href='/nlab/show/analytic+%28%E2%88%9E%2C…
1332 </li>
1333
1334 <li>
1335 <p><a class='existingWikiWord' href='/nlab/show/Goodwillie+spectral+sequ…
1336 </li>
1337 </ul>
1338 </li>
1339 </ul>
1340 </div>
1341
1342 <h4 id='mapping_space'>Mapping space</h4>
1343
1344 <div class='hide'>
1345 <p><strong><a class='existingWikiWord' href='/nlab/show/compact-open+top…
1346
1347 <h3 id='general_abstract'>General abstract</h3>
1348
1349 <ul>
1350 <li>
1351 <p><a class='existingWikiWord' href='/nlab/show/hom-set'>hom-set</a>, <a…
1352 </li>
1353
1354 <li>
1355 <p><a class='existingWikiWord' href='/nlab/show/loop+space+object'>loop …
1356 </li>
1357 </ul>
1358
1359 <h3 id='topology'>Topology</h3>
1360
1361 <ul>
1362 <li>
1363 <p><a class='existingWikiWord' href='/nlab/show/topology+of+mapping+spac…
1364
1365 <ul>
1366 <li><a class='existingWikiWord' href='/nlab/show/compact-open+topology'>…
1367 </ul>
1368 </li>
1369
1370 <li>
1371 <p><a class='existingWikiWord' href='/nlab/show/evaluation+fibration+of+…
1372 </li>
1373
1374 <li>
1375 <p><a class='existingWikiWord' href='/nlab/show/loop+space'>loop space</…
1376 </li>
1377 </ul>
1378
1379 <h3 id='differential_topology'>Differential topology</h3>
1380
1381 <ul>
1382 <li>
1383 <p><a class='existingWikiWord' href='/nlab/show/differential+topology+of…
1384
1385 <ul>
1386 <li><a class='existingWikiWord' href='/nlab/show/C-infinity+topology'>C-…
1387 </ul>
1388 </li>
1389
1390 <li>
1391 <p><a class='existingWikiWord' href='/nlab/show/manifold+structure+of+ma…
1392
1393 <ul>
1394 <li><a class='existingWikiWord' href='/nlab/show/tangent+spaces+of+mappi…
1395 </ul>
1396 </li>
1397
1398 <li>
1399 <p><a class='existingWikiWord' href='/nlab/show/smooth+loop+space'>smoot…
1400 </li>
1401 </ul>
1402
1403 <h3 id='stable_homotopy_theory_2'>Stable homotopy theory</h3>
1404
1405 <ul>
1406 <li><a class='existingWikiWord' href='/nlab/show/function+spectrum'>mapp…
1407 </ul>
1408 <div>
1409 <p>
1410 <a href='/nlab/edit/mapping+space+-+contents'>Edit this sidebar</a>
1411 </p>
1412 </div></div>
1413 </div>
1414 </div>
1415
1416 <h1 id='contents_2'>Contents</h1>
1417 <div class='maruku_toc'><ul><li><a href='#idea'>Idea</a></li><li><a href…
1418 <h2 id='idea'>Idea</h2>
1419
1420 <p>The <a class='existingWikiWord' href='/nlab/show/stabilization'>stabi…
1421
1422 <h2 id='Definition'>Definition</h2>
1423
1424 <p>The stable splitting of mapping spaces discussed <a href='#StableSpli…
1425
1426 <p>The following Def. <a class='maruku-ref' href='#ConfigurationSpacesOf…
1427
1428 <div class='num_defn' id='ConfigurationSpacesOfnPoints'>
1429 <h6 id='definition_2'>Definition</h6>
1430
1431 <p><strong>(<a class='existingWikiWord' href='/nlab/show/configuration+s…
1432
1433 <p>Let <math class='maruku-mathml' display='inline' id='mathml_088ef31fd…
1434
1435 <p>For <math class='maruku-mathml' display='inline' id='mathml_088ef31fd…
1436 <div class='maruku-equation' id='eq:DistinguishableConfigurationSpaceJus…
1437
1438 \mathrm{Conf}^{ord}_{n}(X)
1439 \;\coloneqq\;
1440 \big(
1441 X^n \setminus \mathbf{\Delta}_X^n
1442 \big)
1443 / \partial(X^n)
1444
1445 </annotation></semantics></math></div>
1446 <p>which is the <a class='existingWikiWord' href='/nlab/show/complement'…
1447
1448 <p>Then the <em><strong>configuration space of <math class='maruku-mathm…
1449 <div class='maruku-equation' id='eq:ConfigurationSpaceJustForX'><span cl…
1450
1451 \mathrm{Conf}_{n}(X)
1452 \;\coloneqq\;
1453 Conf_n^{ord}(X)/\Sigma_n
1454 \;=\;
1455 \Big(
1456 \big(
1457 X^n \setminus \mathbf{\Delta}_X^n
1458 \big)
1459 / \partial(X^n)
1460 \Big)
1461 /\Sigma(n)
1462 \,,
1463
1464 </annotation></semantics></math></div>
1465 <p>where <math class='maruku-mathml' display='inline' id='mathml_088ef31…
1466
1467 <p>More generally, let <math class='maruku-mathml' display='inline' id='…
1468 <div class='maruku-equation' id='eq:ConfigurationSpaceWithXAndY'><span c…
1469
1470 \mathrm{Conf}_{n}(X,Y)
1471 \;\coloneqq\;
1472 \Big(
1473 \big(
1474 (
1475 X^n \setminus \mathbf{\Delta}_X^n
1476 )
1477 \times
1478 Y^n
1479 \big)
1480 / \partial(X^n \times Y^n)
1481 \Big)
1482 /\Sigma(n)
1483
1484 </annotation></semantics></math></div>
1485 <p>where now <math class='maruku-mathml' display='inline' id='mathml_088…
1486
1487 <p>This more general definition reduces to the previous case for <math c…
1488 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1489 \mathrm{Conf}_n(X)
1490 \;=\;
1491 \mathrm{Conf}_n(X,\ast)
1492 \,.
1493
1494 </annotation></semantics></math></div>
1495 <p>Finally the <em><strong>configuration space of an arbitrary number of…
1496 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1497 Conf\left( X, Y\right)
1498 \;\coloneqq\;
1499 \left(
1500 \underset{n \in \mathbb{n}}{\sqcup}
1501 \big(
1502 (
1503 X^n \setminus \mathbf{\Delta}_X^n
1504 )
1505 \times
1506 Y^k
1507 \big)
1508 /\Sigma(n)
1509 \right)/\sim
1510
1511 </annotation></semantics></math></div>
1512 <p>by the <a class='existingWikiWord' href='/nlab/show/equivalence+relat…
1513 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1514 \big(
1515 (x_1, y_1), \cdots, (x_{n-1}, y_{n-1}), (x_n, y_n)
1516 \big)
1517 \;\sim\;
1518 \big(
1519 (x_1, y_1), \cdots, (x_{n-1}, y_{n-1})
1520 \big)
1521 \;\;\;\; \Leftrightarrow
1522 \;\;\;\; (x_n, y_n) \in \partial (X \times Y)
1523 \,.
1524
1525 </annotation></semantics></math></div>
1526 <p>This is naturally a <a class='existingWikiWord' href='/nlab/show/filt…
1527 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1528 Conf_{\leq n}\left( X, Y\right)
1529 \;\coloneqq\;
1530 \left(
1531 \underset{k \in \{1, \cdots, n\}}{\sqcup}
1532 \big(
1533 (
1534 X^k \setminus \mathbf{\Delta}_X^k
1535 )
1536 \times
1537 Y^k
1538 \big)
1539 /\Sigma(k)
1540 \right)/\sim
1541 \,.
1542
1543 </annotation></semantics></math></div>
1544 <p>The corresponding <a class='existingWikiWord' href='/nlab/show/quotie…
1545 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1546 Conf_n(X,Y)
1547 \;\simeq\;
1548 Conf_{\leq n}(X,Y) / Conf_{\leq (n-1)}(X,Y)
1549 \,.
1550
1551 </annotation></semantics></math></div></div>
1552
1553 <div class='num_remark' id='ComparisonToNotationInLiterature'>
1554 <h6 id='remark'>Remark</h6>
1555
1556 <p><strong>(comparison to notation in the literature)</strong></p>
1557
1558 <p>The above Def. <a class='maruku-ref' href='#ConfigurationSpacesOfnPoi…
1559 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1560 \array{
1561 \text{ here: }
1562 &amp;&amp;
1563 \array{ \text{ Segal 73,} \\ \text{ Snaith 74}: }
1564 &amp;&amp;
1565 \text{ Bödigheimer 87: }
1566 \\
1567 \\
1568 Conf(\mathbb{R}^d,Y)
1569 &amp;=&amp;
1570 C_d( Y/\partial Y )
1571 &amp;=&amp;
1572 C( \mathbb{R}^d, \emptyset; Y )
1573 \\
1574 \mathrm{Conf}_n\left( \mathbb{R}^d \right)
1575 &amp; = &amp;
1576 F_n C_d( S^0 ) / F_{n-1} C_d( S^0 )
1577 &amp; = &amp;
1578 D_n\left( \mathbb{R}^d, \emptyset; S^0 \right)
1579 \\
1580 \mathrm{Conf}_n\left( \mathbb{R}^d, Y \right)
1581 &amp; = &amp;
1582 F_n C_d( Y/\partial Y ) / F_{n-1} C_d( Y/\partial Y )
1583 &amp; = &amp;
1584 D_n\left( \mathbb{R}^d, \emptyset; Y/\partial Y \right)
1585 \\
1586 \mathrm{Conf}_n( X ) &amp;&amp; &amp;=&amp; D_n\left( X, \partial …
1587 \\
1588 \mathrm{Conf}_n( X, Y ) &amp;&amp; &amp;=&amp; D_n\left( X, \part…
1589 }
1590
1591 </annotation></semantics></math></div>
1592 <p>Notice here that when <math class='maruku-mathml' display='inline' id…
1593 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1594 Y / \partial Y \coloneqq Y \underset{\partial Y}{\sqcup} \ast
1595
1596 </annotation></semantics></math></div>
1597 <p>is <math class='maruku-mathml' display='inline' id='mathml_088ef31fdc…
1598 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1599 \ast/\partial \ast = S^0
1600
1601 </annotation></semantics></math></div>
1602 <p>is the <a class='existingWikiWord' href='/nlab/show/0-sphere'>0-spher…
1603 </div>
1604
1605 <h2 id='Statements'>Statements</h2>
1606
1607 <h3 id='prelude_equivalence_to_the_infinite_configuration_space'>Prelude…
1608
1609 <p>First recall the following equivalence already before <a class='exist…
1610
1611 <div class='num_prop' id='ScanningMapEquivalenceOverCartesianSpace'>
1612 <h6 id='proposition'>Proposition</h6>
1613
1614 <p>For</p>
1615
1616 <ol>
1617 <li>
1618 <p><math class='maruku-mathml' display='inline' id='mathml_088ef31fdc8e1…
1619 </li>
1620
1621 <li>
1622 <p><math class='maruku-mathml' display='inline' id='mathml_088ef31fdc8e1…
1623 </li>
1624 </ol>
1625
1626 <p>the <a class='existingWikiWord' href='/nlab/show/cohomotopy+charge+ma…
1627 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1628 Conf\left(
1629 \mathbb{R}^d, Y
1630 \right)
1631 \overset{scan}{\longrightarrow}
1632 \Omega^d \Sigma^d (Y/\partial Y)
1633
1634 </annotation></semantics></math></div>
1635 <p>between</p>
1636
1637 <ol>
1638 <li>
1639 <p>the configuration space of arbitrary points in <math class='maruku-ma…
1640 </li>
1641
1642 <li>
1643 <p>the <math class='maruku-mathml' display='inline' id='mathml_088ef31fd…
1644 </li>
1645 </ol>
1646
1647 <p>In particular when <math class='maruku-mathml' display='inline' id='m…
1648 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1649 Conf\left(
1650 \mathbb{R}^d, \mathbb{D}^k
1651 \right)
1652 \overset{scan}{\longrightarrow}
1653 \Omega^d S^{ d + k }
1654
1655 </annotation></semantics></math></div>
1656 <p>with the <math class='maruku-mathml' display='inline' id='mathml_088e…
1657 </div>
1658
1659 <p>(<a href='#May72'>May 72, Theorem 2.7</a>, <a href='#Segal73'>Segal 7…
1660
1661 <h3 id='StableSplittings'>Stable splitting of mapping spaces</h3>
1662
1663 <div class='num_prop' id='StableSplittingOfMappingSpacesOutOfEuclideanSp…
1664 <h6 id='proposition_2'>Proposition</h6>
1665
1666 <p><strong>(<a class='existingWikiWord' href='/nlab/show/stable+splittin…
1667
1668 <p>For</p>
1669
1670 <ol>
1671 <li>
1672 <p><math class='maruku-mathml' display='inline' id='mathml_088ef31fdc8e1…
1673 </li>
1674
1675 <li>
1676 <p><math class='maruku-mathml' display='inline' id='mathml_088ef31fdc8e1…
1677 </li>
1678 </ol>
1679
1680 <p>there is a <a class='existingWikiWord' href='/nlab/show/stable+weak+h…
1681 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1682 \Sigma^\infty Conf(\mathbb{R}^d, Y)
1683 \overset{\simeq}{\longrightarrow}
1684 \underset{n \in \mathbb{N}}{\oplus} \Sigma^\infty Conf_n(\mathbb{R}^d,…
1685
1686 </annotation></semantics></math></div>
1687 <p>between</p>
1688
1689 <ol>
1690 <li>
1691 <p>the <a class='existingWikiWord' href='/nlab/show/suspension+spectrum'…
1692 </li>
1693
1694 <li>
1695 <p>the <a class='existingWikiWord' href='/nlab/show/direct+sum'>direct s…
1696 </li>
1697 </ol>
1698
1699 <p>Combined with the <a class='existingWikiWord' href='/nlab/show/stabil…
1700 <div class='maruku-equation' id='eq:StableSplittingOfMappingSpacesOutOfS…
1701
1702 Maps_{cp}(\mathbb{R}^d, \Sigma^d (Y / \partial Y))
1703 =
1704 Maps^{\ast/}( S^d, \Sigma^d (Y / \partial Y))
1705 =
1706 \Omega^d \Sigma^d (Y/\partial Y)
1707 \underoverset{\Sigma^\infty scan}{\simeq}{\longrightarrow}
1708 \Sigma^\infty Conf(\mathbb{R}^d, Y)
1709 \overset{\simeq}{\longrightarrow}
1710 \underset{n \in \mathbb{N}}{\oplus} \Sigma^\infty Conf_n(\mathbb{R}^d,…
1711
1712 </annotation></semantics></math></div>
1713 <p>between the latter direct sum and the <a class='existingWikiWord' hre…
1714 </div>
1715
1716 <p>(<a href='#Snaith74'>Snaith 74, theorem 1.1</a>, <a href='#Boedigheim…
1717
1718 <p>In fact by <a href='#Boedigheimer87'>Bödigheimer 87, Example 5</a> t…
1719 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1720 Maps_{cp}(\mathbb{R}^d, \Sigma^d (Y / \partial Y))
1721 =
1722 Maps^{\ast/}( S^d, \Sigma^d (Y / \partial Y))
1723 \overset{\simeq}{\longrightarrow}
1724 \underset{n \in \mathbb{N}}{\oplus} \Sigma^\infty Conf_n(\mathbb{R}^d …
1725
1726 </annotation></semantics></math></div>
1727 <h3 id='InTermsOfGoodwillieTowers'>In terms of Goodwillie-Taylor towers<…
1728
1729 <p>We discuss the interpretation of the above stable splitting of mappin…
1730
1731 <p>Observe that the <a class='existingWikiWord' href='/nlab/show/configu…
1732 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1733 Conf_n(X,Y)
1734 \;\coloneqq\;
1735 \Big(
1736 \big(
1737 (
1738 X^n \setminus \mathbf{\Delta}_X^n
1739 )
1740 \times
1741 Y^n
1742 \big)
1743 / \partial(X^n \times Y^n)
1744 \Big)
1745 /\Sigma(n)
1746
1747 </annotation></semantics></math></div>
1748 <p>is the <a class='existingWikiWord' href='/nlab/show/quotient+object'>…
1749 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1750 Y^{\times_n}/\partial (Y^{\times_n})
1751 \;\simeq\;
1752 ( Y/\partial Y )^{\wedge_n}
1753 \,.
1754
1755 </annotation></semantics></math></div>
1756 <p>Hence in summary:</p>
1757 <div class='maruku-equation' id='eq:ConfSplitsAsSmashProduct'><span clas…
1758
1759 Conf_n(X, Y)
1760 \;\simeq\;
1761 Conf^{ord}_n(X) \wedge_{\Sigma(n)} \left( Y/\partial Y \right)^{\wedge…
1762 \,,
1763
1764 </annotation></semantics></math></div>
1765 <p>where</p>
1766 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1767 Conf_n^{ord}(X)
1768 \;\coloneqq\;
1769 \left(
1770 X^{\times_n} \setminus \mathbf{\Delta}_X^n
1771 \right)/ \partial(X^n)
1772
1773 </annotation></semantics></math></div>
1774 <p>is the ordered configuration space <a class='maruku-eqref' href='#eq:…
1775
1776 <p>This construction, regarded as a <a class='existingWikiWord' href='/n…
1777 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1778 \array{
1779 Top^{\ast/}
1780 &amp;\longrightarrow&amp;
1781 Spectra
1782 \\
1783 Z
1784 &amp;\mapsto&amp;
1785 \Sigma^\infty Conf^{ord}_n(X) \wedge_{\Sigma(n)} Z^{\wedge_n}
1786 }
1787
1788 </annotation></semantics></math></div>
1789 <p>is an <a class='existingWikiWord' href='/nlab/show/n-homogeneous+%28%…
1790 <div class='maruku-equation' id='eq:IdentifyingTheGoodwillieTaylorStage'…
1791
1792 Z
1793 \;\mapsto\;
1794 \underset{k \in \{1, \cdot, n\}}{\bigoplus}
1795 \Sigma^\infty Conf^{ord}_k(X) \wedge_{\Sigma(k)} Z^{\wedge_k}
1796
1797 </annotation></semantics></math></div>
1798 <p>are <a class='existingWikiWord' href='/nlab/show/n-excisive+%28%E2%88…
1799 <div class='maruku-equation' id='eq:ProjectionMaps'><span class='maruku-…
1800
1801 \array{
1802 Maps_{cp}(\mathbb{R}^d, \Sigma^d Z)
1803 &amp;=&amp;
1804 Maps^{\ast/}( S^d, \Sigma^d Z)
1805 &amp;\simeq&amp;
1806 \underset{k \in \mathbb{N}}{\oplus}
1807 \Sigma^\infty Conf^{ord}_k(\mathbb{R}^d) \wedge_{\Sigma(k)} Z^{\we…
1808 \\
1809 &amp;&amp;
1810 &amp;&amp;
1811 \Big\downarrow {}^{\mathrlap{ p_n }}
1812 \\
1813 &amp;&amp;
1814 &amp;&amp;
1815 \underset{k \in \{1, \cdot, n\}}{\bigoplus}
1816 \Sigma^\infty Conf^{ord}_k( \mathbb{R}^d ) \wedge_{\Sigma(k)} Z^{\w…
1817 }
1818
1819 </annotation></semantics></math></div>
1820 <p>and this is <a class='existingWikiWord' href='/nlab/show/n-connected+…
1821
1822 <p>By <a class='existingWikiWord' href='/nlab/show/Goodwillie+calculus'>…
1823 <div class='maruku-equation' id='eq:TheGoodwillieStagesOfTheMappingSpace…
1824
1825 P_n Maps^{\ast/}( S^d, \Sigma^d (-))
1826 \;\colon\;
1827 Z \mapsto
1828 \underset{k \in \{1, \cdot, n\}}{\bigoplus}
1829 \Sigma^\infty Conf^{ord}_k(S^d, Z)
1830
1831 </annotation></semantics></math></div>
1832 <p>at <math class='maruku-mathml' display='inline' id='mathml_088ef31fdc…
1833 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1834 Maps_{cp}(\mathbb{R}^d, \Sigma^d (-))
1835 =
1836 Maps^{\ast/}( S^d, \Sigma^d (-))
1837 \;\colon\;
1838 Top^{\ast/} \longrightarrow Top^{\ast/}
1839 \,.
1840
1841 </annotation></semantics></math></div>
1842 <p>Therefore the stable splitting theorem <a class='maruku-ref' href='#S…
1843
1844 <p>(<a href='#Arone99'>Arone 99, p. 1-2</a>, <a href='#Goodwillie03'>Goo…
1845
1846 <p><math class='maruku-mathml' display='inline' id='mathml_088ef31fdc8e1…
1847
1848 <h3 id='lax_closed_structure_on_'>Lax closed structure on <math class='m…
1849
1850 <p>Notice that the first stage in the <a class='existingWikiWord' href='…
1851 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1852 \begin{aligned}
1853 P_1 Maps^{\ast/}( S^d, \Sigma^d (Y / \partial Y) )
1854 &amp; =
1855 \Sigma^\infty Conf^{ord}_1( \mathbb{R}^d , Y )
1856 \\
1857 &amp; \simeq
1858 \Sigma^\infty
1859 \underset{\simeq S^0}{\underbrace{Conf^{ord}_1( \mathbb{R}^d )}}
1860 \wedge (Y/\partial Y)
1861 \\
1862 &amp; \simeq
1863 \Sigma^\infty (Y/\partial Y)
1864 \\
1865 &amp; \simeq
1866 \Omega^d \Sigma^d \Sigma^\infty (Y/\partial Y)
1867 \\
1868 &amp; \simeq
1869 Maps\left( \Sigma^\infty S^d, \Sigma^d (Y/\partial Y) \right)
1870 \end{aligned}
1871
1872 </annotation></semantics></math></div>
1873 <p>Here in the first step we used <a class='maruku-eqref' href='#eq:TheG…
1874
1875 <p>Therefore the projection <math class='maruku-mathml' display='inline'…
1876 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
1877 p_1
1878 \;\colon\;
1879 \Sigma^\infty Maps\left( S^d , \Sigma^d (Y /\partial Y) \right)
1880 \longrightarrow
1881 Maps
1882 \left(
1883 \Sigma^\infty S^d, \Sigma^\infty \Sigma^d (Y / \partial Y)
1884 \right)
1885 \,.
1886
1887 </annotation></semantics></math></div>
1888 <p>Since <math class='maruku-mathml' display='inline' id='mathml_088ef31…
1889
1890 <blockquote>
1891 <p>Does it?</p>
1892 </blockquote>
1893
1894 <h2 id='related_concepts'>Related concepts</h2>
1895
1896 <ul>
1897 <li><a class='existingWikiWord' href='/nlab/show/function+spectrum'>mapp…
1898 </ul>
1899
1900 <h2 id='references'>References</h2>
1901
1902 <p>The theorem is originally due to</p>
1903
1904 <ul>
1905 <li id='Snaith74'><a class='existingWikiWord' href='/nlab/show/Victor+Sn…
1906 </ul>
1907
1908 <p>using the homotopy equivalence before stabilization due to</p>
1909
1910 <ul>
1911 <li id='May72'>
1912 <p><a class='existingWikiWord' href='/nlab/show/Peter+May'>Peter May</a>…
1913 </li>
1914
1915 <li id='Segal73'>
1916 <p><a class='existingWikiWord' href='/nlab/show/Graeme+Segal'>Graeme Seg…
1917 </li>
1918 </ul>
1919
1920 <p>An alternative proof is due to</p>
1921
1922 <ul>
1923 <li id='Cohen80'><a class='existingWikiWord' href='/nlab/show/Ralph+Cohe…
1924 </ul>
1925
1926 <p>Review and generalization is due to</p>
1927
1928 <ul>
1929 <li id='Boedigheimer87'><a class='existingWikiWord' href='/nlab/show/Car…
1930 </ul>
1931
1932 <p>Interpretation in terms of the <a class='existingWikiWord' href='/nla…
1933
1934 <ul>
1935 <li id='Arone99'>
1936 <p><a class='existingWikiWord' href='/nlab/show/Gregory+Arone'>Greg Aron…
1937 </li>
1938
1939 <li id='Ching05'>
1940 <p><a class='existingWikiWord' href='/nlab/show/Michael+Ching'>Michael C…
1941 </li>
1942
1943 <li id='Goodwillie03'>
1944 <p><a class='existingWikiWord' href='/nlab/show/Thomas+Goodwillie'>Thoma…
1945 </li>
1946 </ul>
1947
1948 <p>A proof via <a class='existingWikiWord' href='/nlab/show/nonabelian+P…
1949
1950 <ul>
1951 <li>Lauren Bandklayder, <em>Stable splitting of mapping spaces via nonab…
1952 </ul>
1953
1954 <p>See also:</p>
1955
1956 <ul>
1957 <li><a class='existingWikiWord' href='/nlab/show/Doug+Ravenel'>Douglas R…
1958 </ul>
1959
1960 <p>
1961 </p> </div>
1962 </content>
1963 </entry>
1964 <entry>
1965 <title type="html">Tarmo Uustalu</title>
1966 <link rel="alternate" type="application/xhtml+xml" href="https://nca…
1967 <updated>2021-07-02T00:18:56Z</updated>
1968 <published>2021-07-01T06:30:08Z</published>
1969 <id>tag:ncatlab.org,2021-07-01:nLab,Tarmo+Uustalu</id>
1970 <author>
1971 <name>Dmitri Pavlov</name>
1972 </author>
1973 <content type="xhtml" xml:base="https://ncatlab.org/nlab/show/Tarmo+…
1974 <div xmlns="http://www.w3.org/1999/xhtml">
1975 <p>Tarmo Uustalu is a professor at the Dept. of Computer Science of Reyk…
1976
1977 <ul>
1978 <li><a href='https://www.ioc.ee/~tarmo/'>Home page</a></li>
1979 </ul>
1980
1981 <p><div class='property'> category: <a class='category_link' href='/nlab…
1982
1983 <p>
1984 </p> </div>
1985 </content>
1986 </entry>
1987 <entry>
1988 <title type="html">Monster group</title>
1989 <link rel="alternate" type="application/xhtml+xml" href="https://nca…
1990 <updated>2021-07-01T21:40:24Z</updated>
1991 <published>2010-05-19T06:28:51Z</published>
1992 <id>tag:ncatlab.org,2010-05-19:nLab,Monster+group</id>
1993 <author>
1994 <name>Urs Schreiber</name>
1995 </author>
1996 <content type="xhtml" xml:base="https://ncatlab.org/nlab/show/Monste…
1997 <div xmlns="http://www.w3.org/1999/xhtml">
1998 <div class='rightHandSide'>
1999 <div class='toc clickDown' tabindex='0'>
2000 <h3 id='context'>Context</h3>
2001
2002 <h4 id='exceptional_structures'>Exceptional structures</h4>
2003
2004 <div class='hide'>
2005 <p><strong><a class='existingWikiWord' href='/nlab/show/exceptional+stru…
2006
2007 <h2 id='examples'>Examples</h2>
2008
2009 <ul>
2010 <li>
2011 <p><a class='existingWikiWord' href='/nlab/show/sporadic+finite+simple+g…
2012
2013 <ul>
2014 <li>
2015 <p><a class='existingWikiWord' href='/nlab/show/Monster+group'>monster g…
2016 </li>
2017
2018 <li>
2019 <p><a class='existingWikiWord' href='/nlab/show/Mathieu+group'>Mathieu g…
2020 </li>
2021
2022 <li>
2023 <p><a class='existingWikiWord' href='/nlab/show/Conway+group'>Conway gro…
2024 </li>
2025 </ul>
2026 </li>
2027
2028 <li>
2029 <p>exceptional <a class='existingWikiWord' href='/nlab/show/finite+rotat…
2030
2031 <ul>
2032 <li>
2033 <p><a class='existingWikiWord' href='/nlab/show/tetrahedral+group'>tetra…
2034 </li>
2035
2036 <li>
2037 <p><a class='existingWikiWord' href='/nlab/show/octahedral+group'>octahe…
2038 </li>
2039
2040 <li>
2041 <p><a class='existingWikiWord' href='/nlab/show/icosahedral+group'>icosa…
2042 </li>
2043 </ul>
2044 </li>
2045
2046 <li>
2047 <p><a class='existingWikiWord' href='/nlab/show/exceptional+Lie+group'>e…
2048
2049 <ul>
2050 <li>
2051 <p><a class='existingWikiWord' href='/nlab/show/G2'>G2</a></p>
2052 </li>
2053
2054 <li>
2055 <p><a class='existingWikiWord' href='/nlab/show/F4'>F4</a></p>
2056 </li>
2057
2058 <li>
2059 <p><a class='existingWikiWord' href='/nlab/show/E6'>E6</a>, <a class='ex…
2060 </li>
2061 </ul>
2062
2063 <p>and <a class='existingWikiWord' href='/nlab/show/Kac-Moody+group'>Kac…
2064
2065 <ul>
2066 <li><a class='existingWikiWord' href='/nlab/show/E9'>E9</a>, <a class='e…
2067 </ul>
2068 </li>
2069
2070 <li>
2071 <p><a class='existingWikiWord' href='/nlab/show/Dwyer-Wilkerson+H-space'…
2072 </li>
2073
2074 <li>
2075 <p><a class='existingWikiWord' href='/nlab/show/exceptional+Lie+algebra'…
2076 </li>
2077
2078 <li>
2079 <p><a class='existingWikiWord' href='/nlab/show/Albert+algebra'>exceptio…
2080
2081 <ul>
2082 <li><a class='existingWikiWord' href='/nlab/show/Albert+algebra'>Albert …
2083 </ul>
2084 </li>
2085
2086 <li>
2087 <p>exceptional <a class='existingWikiWord' href='/nlab/show/Jordan+super…
2088 </li>
2089
2090 <li>
2091 <p><a class='existingWikiWord' href='/nlab/show/Leech+lattice'>Leech lat…
2092 </li>
2093
2094 <li>
2095 <p><a class='existingWikiWord' href='/nlab/show/Cayley+plane'>Cayley pla…
2096 </li>
2097 </ul>
2098
2099 <h2 id='interrelations'>Interrelations</h2>
2100
2101 <ul>
2102 <li>
2103 <p><a class='existingWikiWord' href='/nlab/show/division+algebra+and+sup…
2104 </li>
2105
2106 <li>
2107 <p><a class='existingWikiWord' href='/nlab/show/Freudenthal+magic+square…
2108 </li>
2109
2110 <li>
2111 <p><a class='existingWikiWord' href='/nlab/show/Moonshine'>moonshine</a>…
2112
2113 <ul>
2114 <li>
2115 <p><a class='existingWikiWord' href='/nlab/show/Mathieu+moonshine'>Mathi…
2116 </li>
2117
2118 <li>
2119 <p><a class='existingWikiWord' href='/nlab/show/umbral+moonshine'>umbral…
2120 </li>
2121
2122 <li>
2123 <p><a class='existingWikiWord' href='/nlab/show/O%27Nan+moonshine'>O&#39…
2124 </li>
2125 </ul>
2126 </li>
2127 </ul>
2128
2129 <h2 id='applications'>Applications</h2>
2130
2131 <ul>
2132 <li>
2133 <p><a class='existingWikiWord' href='/nlab/show/exceptional+geometry'>ex…
2134 </li>
2135
2136 <li>
2137 <p><a class='existingWikiWord' href='/nlab/show/exceptional+field+theory…
2138 </li>
2139 </ul>
2140
2141 <h2 id='philosophy'>Philosophy</h2>
2142
2143 <ul>
2144 <li><a class='existingWikiWord' href='/nlab/show/universal+exceptionalis…
2145 </ul>
2146 </div>
2147
2148 <h4 id='group_theory'>Group Theory</h4>
2149
2150 <div class='hide'>
2151 <p><strong><a class='existingWikiWord' href='/nlab/show/group+theory'>gr…
2152
2153 <ul>
2154 <li><a class='existingWikiWord' href='/nlab/show/group'>group</a>, <a cl…
2155
2156 <li><a class='existingWikiWord' href='/nlab/show/group+object'>group obj…
2157
2158 <li><a class='existingWikiWord' href='/nlab/show/abelian+group'>abelian …
2159
2160 <li><a class='existingWikiWord' href='/nlab/show/action'>group action</a…
2161
2162 <li><a class='existingWikiWord' href='/nlab/show/representation'>represe…
2163
2164 <li><a class='existingWikiWord' href='/nlab/show/progroup'>progroup</a><…
2165
2166 <li><a class='existingWikiWord' href='/nlab/show/homogeneous+space'>homo…
2167 </ul>
2168
2169 <h3 id='classical_groups'>Classical groups</h3>
2170
2171 <ul>
2172 <li>
2173 <p><a class='existingWikiWord' href='/nlab/show/general+linear+group'>ge…
2174 </li>
2175
2176 <li>
2177 <p><a class='existingWikiWord' href='/nlab/show/unitary+group'>unitary g…
2178
2179 <ul>
2180 <li><a class='existingWikiWord' href='/nlab/show/special+unitary+group'>…
2181 </ul>
2182 </li>
2183
2184 <li>
2185 <p><a class='existingWikiWord' href='/nlab/show/orthogonal+group'>orthog…
2186
2187 <ul>
2188 <li><a class='existingWikiWord' href='/nlab/show/special+orthogonal+grou…
2189 </ul>
2190 </li>
2191
2192 <li>
2193 <p><a class='existingWikiWord' href='/nlab/show/symplectic+group'>symple…
2194 </li>
2195 </ul>
2196
2197 <h3 id='finite_groups'>Finite groups</h3>
2198
2199 <ul>
2200 <li>
2201 <p><a class='existingWikiWord' href='/nlab/show/finite+group'>finite gro…
2202 </li>
2203
2204 <li>
2205 <p><a class='existingWikiWord' href='/nlab/show/symmetric+group'>symmetr…
2206 </li>
2207
2208 <li>
2209 <p><a class='existingWikiWord' href='/nlab/show/classification+of+finite…
2210 </li>
2211
2212 <li>
2213 <p><a class='existingWikiWord' href='/nlab/show/sporadic+finite+simple+g…
2214
2215 <ul>
2216 <li><a class='existingWikiWord' href='/nlab/show/Monster+group'>Monster …
2217 </ul>
2218 </li>
2219 </ul>
2220
2221 <h3 id='group_schemes'>Group schemes</h3>
2222
2223 <ul>
2224 <li><a class='existingWikiWord' href='/nlab/show/algebraic+group'>algebr…
2225
2226 <li><a class='existingWikiWord' href='/nlab/show/abelian+variety'>abelia…
2227 </ul>
2228
2229 <h3 id='topological_groups'>Topological groups</h3>
2230
2231 <ul>
2232 <li>
2233 <p><a class='existingWikiWord' href='/nlab/show/topological+group'>topol…
2234 </li>
2235
2236 <li>
2237 <p><a class='existingWikiWord' href='/nlab/show/compact+topological+grou…
2238 </li>
2239
2240 <li>
2241 <p><a class='existingWikiWord' href='/nlab/show/maximal+compact+subgroup…
2242 </li>
2243
2244 <li>
2245 <p><a class='existingWikiWord' href='/nlab/show/string+group'>string gro…
2246 </li>
2247 </ul>
2248
2249 <h3 id='lie_groups'>Lie groups</h3>
2250
2251 <ul>
2252 <li>
2253 <p><a class='existingWikiWord' href='/nlab/show/Lie+group'>Lie group</a>…
2254 </li>
2255
2256 <li>
2257 <p><a class='existingWikiWord' href='/nlab/show/compact+Lie+group'>compa…
2258 </li>
2259
2260 <li>
2261 <p><a class='existingWikiWord' href='/nlab/show/Kac-Moody+group'>Kac-Moo…
2262 </li>
2263 </ul>
2264
2265 <h3 id='superlie_groups'>Super-Lie groups</h3>
2266
2267 <ul>
2268 <li>
2269 <p><a class='existingWikiWord' href='/nlab/show/supergroup'>super Lie gr…
2270 </li>
2271
2272 <li>
2273 <p><a class='existingWikiWord' href='/nlab/show/super+Euclidean+group'>s…
2274 </li>
2275 </ul>
2276
2277 <h3 id='higher_groups'>Higher groups</h3>
2278
2279 <ul>
2280 <li>
2281 <p><a class='existingWikiWord' href='/nlab/show/2-group'>2-group</a></p>
2282
2283 <ul>
2284 <li><a class='existingWikiWord' href='/nlab/show/crossed+module'>crossed…
2285 </ul>
2286 </li>
2287
2288 <li>
2289 <p><a class='existingWikiWord' href='/nlab/show/n-group'>n-group</a></p>
2290 </li>
2291
2292 <li>
2293 <p><a class='existingWikiWord' href='/nlab/show/infinity-group'>∞-grou…
2294
2295 <ul>
2296 <li>
2297 <p><a class='existingWikiWord' href='/nlab/show/simplicial+group'>simpli…
2298 </li>
2299
2300 <li>
2301 <p><a class='existingWikiWord' href='/nlab/show/crossed+complex'>crossed…
2302 </li>
2303
2304 <li>
2305 <p><a class='existingWikiWord' href='/nlab/show/k-tuply+groupal+n-groupo…
2306 </li>
2307
2308 <li>
2309 <p><a class='existingWikiWord' href='/nlab/show/spectrum'>spectrum</a></…
2310 </li>
2311 </ul>
2312 </li>
2313
2314 <li>
2315 <p><a class='existingWikiWord' href='/nlab/show/circle+n-group'>circle n…
2316 </li>
2317 </ul>
2318
2319 <h3 id='cohomology_and_extensions'>Cohomology and Extensions</h3>
2320
2321 <ul>
2322 <li>
2323 <p><a class='existingWikiWord' href='/nlab/show/group+cohomology'>group …
2324 </li>
2325
2326 <li>
2327 <p><a class='existingWikiWord' href='/nlab/show/group+extension'>group e…
2328 </li>
2329
2330 <li>
2331 <p><a class='existingWikiWord' href='/nlab/show/infinity-group+extension…
2332 </li>
2333 </ul>
2334
2335 <h3 id='_related_concepts'>Related concepts</h3>
2336
2337 <ul>
2338 <li><a class='existingWikiWord' href='/nlab/show/quantum+group'>quantum …
2339 </ul>
2340 <div>
2341 <p>
2342 <a href='/nlab/edit/group+theory+-+contents'>Edit this sidebar</a>
2343 </p>
2344 </div></div>
2345 </div>
2346 </div>
2347
2348 <h1 id='contents'>Contents</h1>
2349 <div class='maruku_toc'><ul><li><a href='#idea'>Idea</a></li><li><a href…
2350 <h2 id='idea'>Idea</h2>
2351
2352 <p>The <strong>Monster group</strong> <math class='maruku-mathml' displa…
2353 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
2354 \begin{aligned}
2355 &amp; 2^{46}\cdot 3^{20}\cdot 5^9\cdot 7^6\cdot 11^2\cdot 13^3\cdot 17\c…
2356 \\
2357 &amp; = 808017424794512875886459904961710757005754368000000000
2358 \end{aligned}
2359
2360 </annotation></semantics></math></div>
2361 <p>and contains all but six (the ‘<a class='existingWikiWord' href='/n…
2362
2363 <p>See also <a class='existingWikiWord' href='/nlab/show/Moonshine'>Moon…
2364
2365 <h2 id='history'>History</h2>
2366
2367 <p>The Monster group was predicted to exist by <a class='existingWikiWor…
2368
2369 <ul>
2370 <li><a class='existingWikiWord' href='/nlab/show/Robert+Griess'>Robert G…
2371 </ul>
2372
2373 <p>Griess proved the existence of the largest simple sporadic group. The…
2374
2375 <p>After Griess found this algebra <a class='existingWikiWord' href='/nl…
2376
2377 <p>There is a school of thought, going back to at least <a class='existi…
2378
2379 <h2 id='presentation'>Presentation</h2>
2380
2381 <h3 id='via_coxeter_groups'>Via Coxeter groups</h3>
2382
2383 <p>The Monster admits a reasonably succinct description in terms of <a c…
2384
2385 <p>Regard <math class='maruku-mathml' display='inline' id='mathml_b35f69…
2386 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
2387 <p>the resulting quotient <math class='maruku-mathml' display='inline' i…
2388
2389 <p>It turns out that <math class='maruku-mathml' display='inline' id='ma…
2390 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
2391 <p>This implicitly describes the Monster in terms of 12 generators and 8…
2392
2393 <p>Such “<math class='maruku-mathml' display='inline' id='mathml_b35f6…
2394
2395 <h3 id='ViaAutomorphisms'>Via automorphisms of a super vertex operator a…
2396
2397 <p>There is a <a class='existingWikiWord' href='/nlab/show/super+vertex+…
2398
2399 <p>(<a href='#FrenkelLepowskiMeurman89'>Frenkel-Lepowski-Meurman 89</a>,…
2400
2401 <h2 id='related_concepts_2'>Related concepts</h2>
2402
2403 <ul>
2404 <li>
2405 <p><a class='existingWikiWord' href='/nlab/show/Moonshine'>Moonshine</a>…
2406 </li>
2407
2408 <li>
2409 <p><a class='existingWikiWord' href='/nlab/show/Monster+vertex+operator+…
2410 </li>
2411
2412 <li>
2413 <p><a class='existingWikiWord' href='/nlab/show/Mathieu+group'>Mathieu g…
2414 </li>
2415 </ul>
2416
2417 <h2 id='references'>References</h2>
2418
2419 <ul>
2420 <li>
2421 <p><a href='http://mathoverflow.net/users/39521/adam-p-goucher'>Adam P. …
2422 </li>
2423
2424 <li id='Iv'>
2425 <p>Alexander Ivanov, <em>Y-groups via transitive extension</em>, Journal…
2426 </li>
2427
2428 <li id='Iv2'>
2429 <p>A. A. Ivanov, <em>Constructing the Monster via its Y-presentation</em…
2430 </li>
2431
2432 <li id='FrenkelLepowskiMeurman89'>
2433 <p><a class='existingWikiWord' href='/nlab/show/Igor+Frenkel'>Igor Frenk…
2434 </li>
2435
2436 <li id='GriessLam11'>
2437 <p><a class='existingWikiWord' href='/nlab/show/Robert+Griess'>Robert Gr…
2438 </li>
2439
2440 <li>
2441 <p><a class='existingWikiWord' href='/nlab/show/Andr%C3%A9+Henriques'>An…
2442 </li>
2443 </ul>
2444
2445 <p>Possible relation to <a class='existingWikiWord' href='/nlab/show/bos…
2446
2447 <ul>
2448 <li><a class='existingWikiWord' href='/nlab/show/Alessio+Marrani'>Alessi…
2449 </ul>
2450 <div style='float: right; margin: 0 20px 10px 20px;'><img alt='The Monst…
2451 <p>
2452 </p>
2453
2454 <p>
2455 </p>
2456
2457 <p>
2458 </p> </div>
2459 </content>
2460 </entry>
2461 <entry>
2462 <title type="html">Moonshine</title>
2463 <link rel="alternate" type="application/xhtml+xml" href="https://nca…
2464 <updated>2021-07-01T21:06:02Z</updated>
2465 <published>2010-05-18T20:54:08Z</published>
2466 <id>tag:ncatlab.org,2010-05-18:nLab,Moonshine</id>
2467 <author>
2468 <name>Urs Schreiber</name>
2469 </author>
2470 <content type="xhtml" xml:base="https://ncatlab.org/nlab/show/Moonsh…
2471 <div xmlns="http://www.w3.org/1999/xhtml">
2472 <div class='rightHandSide'>
2473 <div class='toc clickDown' tabindex='0'>
2474 <h3 id='context'>Context</h3>
2475
2476 <h4 id='exceptional_structures'>Exceptional structures</h4>
2477
2478 <div class='hide'>
2479 <p><strong><a class='existingWikiWord' href='/nlab/show/exceptional+stru…
2480
2481 <h2 id='examples'>Examples</h2>
2482
2483 <ul>
2484 <li>
2485 <p><a class='existingWikiWord' href='/nlab/show/sporadic+finite+simple+g…
2486
2487 <ul>
2488 <li>
2489 <p><a class='existingWikiWord' href='/nlab/show/Monster+group'>monster g…
2490 </li>
2491
2492 <li>
2493 <p><a class='existingWikiWord' href='/nlab/show/Mathieu+group'>Mathieu g…
2494 </li>
2495
2496 <li>
2497 <p><a class='existingWikiWord' href='/nlab/show/Conway+group'>Conway gro…
2498 </li>
2499 </ul>
2500 </li>
2501
2502 <li>
2503 <p>exceptional <a class='existingWikiWord' href='/nlab/show/finite+rotat…
2504
2505 <ul>
2506 <li>
2507 <p><a class='existingWikiWord' href='/nlab/show/tetrahedral+group'>tetra…
2508 </li>
2509
2510 <li>
2511 <p><a class='existingWikiWord' href='/nlab/show/octahedral+group'>octahe…
2512 </li>
2513
2514 <li>
2515 <p><a class='existingWikiWord' href='/nlab/show/icosahedral+group'>icosa…
2516 </li>
2517 </ul>
2518 </li>
2519
2520 <li>
2521 <p><a class='existingWikiWord' href='/nlab/show/exceptional+Lie+group'>e…
2522
2523 <ul>
2524 <li>
2525 <p><a class='existingWikiWord' href='/nlab/show/G2'>G2</a></p>
2526 </li>
2527
2528 <li>
2529 <p><a class='existingWikiWord' href='/nlab/show/F4'>F4</a></p>
2530 </li>
2531
2532 <li>
2533 <p><a class='existingWikiWord' href='/nlab/show/E6'>E6</a>, <a class='ex…
2534 </li>
2535 </ul>
2536
2537 <p>and <a class='existingWikiWord' href='/nlab/show/Kac-Moody+group'>Kac…
2538
2539 <ul>
2540 <li><a class='existingWikiWord' href='/nlab/show/E9'>E9</a>, <a class='e…
2541 </ul>
2542 </li>
2543
2544 <li>
2545 <p><a class='existingWikiWord' href='/nlab/show/Dwyer-Wilkerson+H-space'…
2546 </li>
2547
2548 <li>
2549 <p><a class='existingWikiWord' href='/nlab/show/exceptional+Lie+algebra'…
2550 </li>
2551
2552 <li>
2553 <p><a class='existingWikiWord' href='/nlab/show/Albert+algebra'>exceptio…
2554
2555 <ul>
2556 <li><a class='existingWikiWord' href='/nlab/show/Albert+algebra'>Albert …
2557 </ul>
2558 </li>
2559
2560 <li>
2561 <p>exceptional <a class='existingWikiWord' href='/nlab/show/Jordan+super…
2562 </li>
2563
2564 <li>
2565 <p><a class='existingWikiWord' href='/nlab/show/Leech+lattice'>Leech lat…
2566 </li>
2567
2568 <li>
2569 <p><a class='existingWikiWord' href='/nlab/show/Cayley+plane'>Cayley pla…
2570 </li>
2571 </ul>
2572
2573 <h2 id='interrelations'>Interrelations</h2>
2574
2575 <ul>
2576 <li>
2577 <p><a class='existingWikiWord' href='/nlab/show/division+algebra+and+sup…
2578 </li>
2579
2580 <li>
2581 <p><a class='existingWikiWord' href='/nlab/show/Freudenthal+magic+square…
2582 </li>
2583
2584 <li>
2585 <p><a class='existingWikiWord' href='/nlab/show/Moonshine'>moonshine</a>…
2586
2587 <ul>
2588 <li>
2589 <p><a class='existingWikiWord' href='/nlab/show/Mathieu+moonshine'>Mathi…
2590 </li>
2591
2592 <li>
2593 <p><a class='existingWikiWord' href='/nlab/show/umbral+moonshine'>umbral…
2594 </li>
2595
2596 <li>
2597 <p><a class='existingWikiWord' href='/nlab/show/O%27Nan+moonshine'>O&#39…
2598 </li>
2599 </ul>
2600 </li>
2601 </ul>
2602
2603 <h2 id='applications'>Applications</h2>
2604
2605 <ul>
2606 <li>
2607 <p><a class='existingWikiWord' href='/nlab/show/exceptional+geometry'>ex…
2608 </li>
2609
2610 <li>
2611 <p><a class='existingWikiWord' href='/nlab/show/exceptional+field+theory…
2612 </li>
2613 </ul>
2614
2615 <h2 id='philosophy'>Philosophy</h2>
2616
2617 <ul>
2618 <li><a class='existingWikiWord' href='/nlab/show/universal+exceptionalis…
2619 </ul>
2620 </div>
2621 </div>
2622 </div>
2623
2624 <h1 id='contents'>Contents</h1>
2625 <div class='maruku_toc'><ul><li><a href='#idea'>Idea</a></li><li><a href…
2626 <h2 id='idea'>Idea</h2>
2627
2628 <p>Moonshine usually refers to the mysterious connections between the <a…
2629
2630 <p>The whole idea of moonshine began with <a class='existingWikiWord' hr…
2631 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
2632 j(\tau) = q^{-1} + 744 + 196884q + 21493760q^{2} + \dots
2633
2634 </annotation></semantics></math></div>
2635 <p>where <math class='maruku-mathml' display='inline' id='mathml_5fa8578…
2636
2637 <p>But the monster was merely <em>conjectured</em> to exist until Griess…
2638
2639 <p><a href='#FrenkelLepowskiMeurman89'>Frenkel-Lepowski-Meurman 89</a> c…
2640
2641 <p>To cut the story short, we end up getting from the Monster group to a…
2642
2643 <h2 id='AutomorphismGroupsOfVertexOperatorAlgebras'>Automorphism groups …
2644
2645 <p>Realizations of <a class='existingWikiWord' href='/nlab/show/sporadic…
2646
2647 <ul>
2648 <li>
2649 <p>The <a class='existingWikiWord' href='/nlab/show/Conway+group'>Conway…
2650
2651 <p>(<a href='#Duncan05'>Duncan 05</a>, see also <a href='#PaquettePersso…
2652 </li>
2653
2654 <li>
2655 <p>similarly, there is a super VOA, the <em><a class='existingWikiWord' …
2656
2657 <p>(<a href='#FrenkelLepowskiMeurman89'>Frenkel-Lepowski-Meurman 89</a>,…
2658 </li>
2659 </ul>
2660
2661 <h2 id='related_concepts'>Related concepts</h2>
2662
2663 <ul>
2664 <li>
2665 <p><a class='existingWikiWord' href='/nlab/show/Monster+group'>Monster</…
2666 </li>
2667
2668 <li>
2669 <p>moonshine</p>
2670
2671 <ul>
2672 <li>
2673 <p><a class='existingWikiWord' href='/nlab/show/Mathieu+moonshine'>Mathi…
2674 </li>
2675
2676 <li>
2677 <p><a class='existingWikiWord' href='/nlab/show/umbral+moonshine'>umbral…
2678 </li>
2679
2680 <li>
2681 <p><a class='existingWikiWord' href='/nlab/show/O%27Nan+moonshine'>O&#39…
2682 </li>
2683 </ul>
2684 </li>
2685
2686 <li>
2687 <p><a class='existingWikiWord' href='/nlab/show/automorphism+of+a+vertex…
2688 </li>
2689 </ul>
2690
2691 <h2 id='references'>References</h2>
2692
2693 <h3 id='general'>General</h3>
2694
2695 <ul>
2696 <li>
2697 <p><a class='existingWikiWord' href='/nlab/show/Richard+Borcherds'>Richa…
2698 </li>
2699
2700 <li>
2701 <p>John F. R. Duncan, Michael J. Griffin, Ken Ono, <em>Moonshine</em> (<…
2702 </li>
2703
2704 <li id='GriessLam11'>
2705 <p><a class='existingWikiWord' href='/nlab/show/Robert+Griess'>Robert Gr…
2706 </li>
2707
2708 <li id='FrenkelLepowskiMeurman89'>
2709 <p><a class='existingWikiWord' href='/nlab/show/Igor+Frenkel'>Igor Frenk…
2710 </li>
2711
2712 <li>
2713 <p><a class='existingWikiWord' href='/nlab/show/Terry+Gannon'>Terry Gann…
2714 </li>
2715
2716 <li>
2717 <p><a class='existingWikiWord' href='/nlab/show/Terry+Gannon'>Terry Gann…
2718 </li>
2719
2720 <li>
2721 <p>Koichiro Harada, <em>“Moonshine” of finite groups</em>. EMS Serie…
2722 </li>
2723
2724 <li>
2725 <p>Griess, Robert L., Jr.; Lam, Ching Hung <em>A moonshine path from E8 …
2726 </li>
2727
2728 <li>
2729 <p>Jae-Hyun Yang “Kac-Moody algebras, the Monstrous Moonshine, Jacobi …
2730 </li>
2731
2732 <li>
2733 <p>Vassilis Anagiannis, <a class='existingWikiWord' href='/nlab/show/Mir…
2734 </li>
2735 </ul>
2736
2737 <h3 id='historical_references'>Historical References</h3>
2738
2739 <ul>
2740 <li>
2741 <p><a class='existingWikiWord' href='/nlab/show/John+Horton+Conway'>John…
2742 </li>
2743
2744 <li id='FrenkelLepowskiMeurman89'>
2745 <p><a class='existingWikiWord' href='/nlab/show/Igor+Frenkel'>Igor Frenk…
2746 </li>
2747
2748 <li>
2749 <p><a class='existingWikiWord' href='/nlab/show/Robert+Griess'>Robert Gr…
2750 </li>
2751
2752 <li>
2753 <p>John G. Thompson, “Some numerology between the Fischer-Griess Monst…
2754 </li>
2755 </ul>
2756
2757 <h3 id='FurtherDevelomentsReferences'>Further developments</h3>
2758
2759 <ul>
2760 <li>
2761 <p><a class='existingWikiWord' href='/nlab/show/Miranda+Cheng'>Miranda C…
2762 </li>
2763
2764 <li>
2765 <p>John F. R. Duncan, Michael J. Griffin and Ken Ono, <em>Proof of the U…
2766 </li>
2767
2768 <li>
2769 <p><a class='existingWikiWord' href='/nlab/show/Scott+Carnahan'>Scott Ca…
2770 </li>
2771 </ul>
2772
2773 <h3 id='realization_in_superstring_theory'>Realization in superstring th…
2774
2775 <p>Discussion of possible realizations in <a class='existingWikiWord' hr…
2776
2777 <ul>
2778 <li>
2779 <p>S. Chaudhuri, D.A. Lowe, <em>Monstrous String-String Duality</em>, Nu…
2780 </li>
2781
2782 <li id='Duncan05'>
2783 <p>John F. Duncan, <em>Super-moonshine for Conway’s largest sporadic g…
2784 </li>
2785
2786 <li id='PaquettePerssonVolpato16'>
2787 <p><a class='existingWikiWord' href='/nlab/show/Natalie+Paquette'>Natali…
2788 </li>
2789
2790 <li id='KachruPaquetteVolpato16'>
2791 <p><a class='existingWikiWord' href='/nlab/show/Shamit+Kachru'>Shamit Ka…
2792 </li>
2793
2794 <li id='PaquettePerssonVolpato17'>
2795 <p><a class='existingWikiWord' href='/nlab/show/Natalie+Paquette'>Natali…
2796 </li>
2797
2798 <li>
2799 <p><a class='existingWikiWord' href='/nlab/show/Shamit+Kachru'>Shamit Ka…
2800 </li>
2801 </ul>
2802
2803 <p>Specifically in relation to <a class='existingWikiWord' href='/nlab/s…
2804
2805 <ul>
2806 <li id='ChengHarrisonVolpatoZimet16'><a class='existingWikiWord' href='/…
2807 </ul>
2808
2809 <p>Possible relation to <a class='existingWikiWord' href='/nlab/show/bos…
2810
2811 <ul>
2812 <li><a class='existingWikiWord' href='/nlab/show/Alessio+Marrani'>Alessi…
2813 </ul>
2814
2815 <p>
2816
2817 </p>
2818
2819 <p>
2820
2821 </p>
2822
2823 <p>
2824
2825 </p> </div>
2826 </content>
2827 </entry>
2828 <entry>
2829 <title type="html">geometric realization of categories</title>
2830 <link rel="alternate" type="application/xhtml+xml" href="https://nca…
2831 <updated>2021-07-01T17:07:36Z</updated>
2832 <published>2011-05-30T18:19:35Z</published>
2833 <id>tag:ncatlab.org,2011-05-30:nLab,geometric+realization+of+categor…
2834 <author>
2835 <name>Dmitri Pavlov</name>
2836 </author>
2837 <content type="xhtml" xml:base="https://ncatlab.org/nlab/show/geomet…
2838 <div xmlns="http://www.w3.org/1999/xhtml">
2839 <div class='rightHandSide'>
2840 <div class='toc clickDown' tabindex='0'>
2841 <h3 id='context'>Context</h3>
2842
2843 <h4 id='homotopy_theory'>Homotopy theory</h4>
2844
2845 <div class='hide'>
2846 <p><strong><a class='existingWikiWord' href='/nlab/show/homotopy+theory'…
2847
2848 <p>flavors: <a class='existingWikiWord' href='/nlab/show/stable+homotopy…
2849
2850 <p>models: <a class='existingWikiWord' href='/nlab/show/topological+homo…
2851
2852 <p>see also <strong><a class='existingWikiWord' href='/nlab/show/algebra…
2853
2854 <p><strong>Introductions</strong></p>
2855
2856 <ul>
2857 <li>
2858 <p><a class='existingWikiWord' href='/nlab/show/Introduction+to+Topology…
2859 </li>
2860
2861 <li>
2862 <p><a class='existingWikiWord' href='/nlab/show/Introduction+to+Homotopy…
2863 </li>
2864
2865 <li>
2866 <p><a class='existingWikiWord' href='/nlab/show/geometry+of+physics+--+h…
2867 </li>
2868 </ul>
2869
2870 <p><strong>Definitions</strong></p>
2871
2872 <ul>
2873 <li>
2874 <p><a class='existingWikiWord' href='/nlab/show/homotopy'>homotopy</a>, …
2875 </li>
2876
2877 <li>
2878 <p><a class='existingWikiWord' href='/nlab/show/homotopy+type'>homotopy …
2879 </li>
2880
2881 <li>
2882 <p><a class='existingWikiWord' href='/nlab/show/Pi-algebra'>Pi-algebra</…
2883 </li>
2884
2885 <li>
2886 <p><a class='existingWikiWord' href='/nlab/show/homotopy+coherent+catego…
2887
2888 <ul>
2889 <li>
2890 <p><a class='existingWikiWord' href='/nlab/show/homotopical+category'>ho…
2891
2892 <ul>
2893 <li>
2894 <p><a class='existingWikiWord' href='/nlab/show/model+category'>model ca…
2895 </li>
2896
2897 <li>
2898 <p><a class='existingWikiWord' href='/nlab/show/category+of+fibrant+obje…
2899 </li>
2900
2901 <li>
2902 <p><a class='existingWikiWord' href='/nlab/show/Waldhausen+category'>Wal…
2903 </li>
2904 </ul>
2905 </li>
2906
2907 <li>
2908 <p><a class='existingWikiWord' href='/nlab/show/homotopy+category'>homot…
2909
2910 <ul>
2911 <li><a class='existingWikiWord' href='/nlab/show/Ho%28Top%29'>Ho(Top)</a…
2912 </ul>
2913 </li>
2914 </ul>
2915 </li>
2916
2917 <li>
2918 <p><a class='existingWikiWord' href='/nlab/show/%28infinity%2C1%29-categ…
2919
2920 <ul>
2921 <li><a class='existingWikiWord' href='/nlab/show/homotopy+category+of+an…
2922 </ul>
2923 </li>
2924 </ul>
2925
2926 <p><strong>Paths and cylinders</strong></p>
2927
2928 <ul>
2929 <li>
2930 <p><a class='existingWikiWord' href='/nlab/show/homotopy'>left homotopy<…
2931
2932 <ul>
2933 <li>
2934 <p><a class='existingWikiWord' href='/nlab/show/cylinder+object'>cylinde…
2935 </li>
2936
2937 <li>
2938 <p><a class='existingWikiWord' href='/nlab/show/mapping+cone'>mapping co…
2939 </li>
2940 </ul>
2941 </li>
2942
2943 <li>
2944 <p><a class='existingWikiWord' href='/nlab/show/homotopy'>right homotopy…
2945
2946 <ul>
2947 <li>
2948 <p><a class='existingWikiWord' href='/nlab/show/path+space+object'>path …
2949 </li>
2950
2951 <li>
2952 <p><a class='existingWikiWord' href='/nlab/show/mapping+cocone'>mapping …
2953 </li>
2954
2955 <li>
2956 <p><a class='existingWikiWord' href='/nlab/show/generalized+universal+bu…
2957 </li>
2958 </ul>
2959 </li>
2960
2961 <li>
2962 <p><a class='existingWikiWord' href='/nlab/show/interval+object'>interva…
2963
2964 <ul>
2965 <li>
2966 <p><a class='existingWikiWord' href='/nlab/show/localization+at+geometri…
2967 </li>
2968
2969 <li>
2970 <p><a class='existingWikiWord' href='/nlab/show/infinitesimal+interval+o…
2971 </li>
2972 </ul>
2973 </li>
2974 </ul>
2975
2976 <p><strong>Homotopy groups</strong></p>
2977
2978 <ul>
2979 <li>
2980 <p><a class='existingWikiWord' href='/nlab/show/homotopy+group'>homotopy…
2981
2982 <ul>
2983 <li>
2984 <p><a class='existingWikiWord' href='/nlab/show/fundamental+group'>funda…
2985
2986 <ul>
2987 <li><a class='existingWikiWord' href='/nlab/show/fundamental+group+of+a+…
2988 </ul>
2989 </li>
2990
2991 <li>
2992 <p><a class='existingWikiWord' href='/nlab/show/Brown-Grossman+homotopy+…
2993 </li>
2994
2995 <li>
2996 <p><a class='existingWikiWord' href='/nlab/show/categorical+homotopy+gro…
2997 </li>
2998
2999 <li>
3000 <p><a class='existingWikiWord' href='/nlab/show/geometric+homotopy+group…
3001 </li>
3002 </ul>
3003 </li>
3004
3005 <li>
3006 <p><a class='existingWikiWord' href='/nlab/show/fundamental+infinity-gro…
3007
3008 <ul>
3009 <li>
3010 <p><a class='existingWikiWord' href='/nlab/show/fundamental+groupoid'>fu…
3011
3012 <ul>
3013 <li><a class='existingWikiWord' href='/nlab/show/path+groupoid'>path gro…
3014 </ul>
3015 </li>
3016
3017 <li>
3018 <p><a class='existingWikiWord' href='/nlab/show/fundamental+infinity-gro…
3019 </li>
3020
3021 <li>
3022 <p><a class='existingWikiWord' href='/nlab/show/fundamental+infinity-gro…
3023 </li>
3024 </ul>
3025 </li>
3026
3027 <li>
3028 <p><a class='existingWikiWord' href='/nlab/show/fundamental+%28infinity%…
3029
3030 <ul>
3031 <li><a class='existingWikiWord' href='/nlab/show/fundamental+category'>f…
3032 </ul>
3033 </li>
3034 </ul>
3035
3036 <p><strong>Basic facts</strong></p>
3037
3038 <ul>
3039 <li><a class='existingWikiWord' href='/nlab/show/fundamental+group+of+th…
3040 </ul>
3041
3042 <p><strong>Theorems</strong></p>
3043
3044 <ul>
3045 <li>
3046 <p><a class='existingWikiWord' href='/nlab/show/fundamental+theorem+of+c…
3047 </li>
3048
3049 <li>
3050 <p><a class='existingWikiWord' href='/nlab/show/Freudenthal+suspension+t…
3051 </li>
3052
3053 <li>
3054 <p><a class='existingWikiWord' href='/nlab/show/Blakers-Massey+theorem'>…
3055 </li>
3056
3057 <li>
3058 <p><a class='existingWikiWord' href='/nlab/show/higher+homotopy+van+Kamp…
3059 </li>
3060
3061 <li>
3062 <p><a class='existingWikiWord' href='/nlab/show/nerve+theorem'>nerve the…
3063 </li>
3064
3065 <li>
3066 <p><a class='existingWikiWord' href='/nlab/show/Whitehead+theorem'>White…
3067 </li>
3068
3069 <li>
3070 <p><a class='existingWikiWord' href='/nlab/show/Hurewicz+theorem'>Hurewi…
3071 </li>
3072
3073 <li>
3074 <p><a class='existingWikiWord' href='/nlab/show/Galois+theory'>Galois th…
3075 </li>
3076
3077 <li>
3078 <p><a class='existingWikiWord' href='/nlab/show/homotopy+hypothesis'>hom…
3079 </li>
3080 </ul>
3081 </div>
3082
3083 <h4 id='category_theory'>Category theory</h4>
3084
3085 <div class='hide'>
3086 <p><strong><a class='existingWikiWord' href='/nlab/show/category+theory'…
3087
3088 <h2 id='concepts'>Concepts</h2>
3089
3090 <ul>
3091 <li>
3092 <p><a class='existingWikiWord' href='/nlab/show/category'>category</a></…
3093 </li>
3094
3095 <li>
3096 <p><a class='existingWikiWord' href='/nlab/show/functor'>functor</a></p>
3097 </li>
3098
3099 <li>
3100 <p><a class='existingWikiWord' href='/nlab/show/natural+transformation'>…
3101 </li>
3102
3103 <li>
3104 <p><a class='existingWikiWord' href='/nlab/show/Cat'>Cat</a></p>
3105 </li>
3106 </ul>
3107
3108 <h2 id='universal_constructions'>Universal constructions</h2>
3109
3110 <ul>
3111 <li>
3112 <p><a class='existingWikiWord' href='/nlab/show/universal+construction'>…
3113
3114 <ul>
3115 <li>
3116 <p><a class='existingWikiWord' href='/nlab/show/representable+functor'>r…
3117 </li>
3118
3119 <li>
3120 <p><a class='existingWikiWord' href='/nlab/show/adjoint+functor'>adjoint…
3121 </li>
3122
3123 <li>
3124 <p><a class='existingWikiWord' href='/nlab/show/limit'>limit</a>/<a clas…
3125 </li>
3126
3127 <li>
3128 <p><a class='existingWikiWord' href='/nlab/show/weighted+limit'>weighted…
3129 </li>
3130
3131 <li>
3132 <p><a class='existingWikiWord' href='/nlab/show/end'>end</a>/<a class='e…
3133 </li>
3134
3135 <li>
3136 <p><a class='existingWikiWord' href='/nlab/show/Kan+extension'>Kan exten…
3137 </li>
3138 </ul>
3139 </li>
3140 </ul>
3141
3142 <h2 id='theorems'>Theorems</h2>
3143
3144 <ul>
3145 <li>
3146 <p><a class='existingWikiWord' href='/nlab/show/Yoneda+lemma'>Yoneda lem…
3147 </li>
3148
3149 <li>
3150 <p><a class='existingWikiWord' href='/nlab/show/Isbell+duality'>Isbell d…
3151 </li>
3152
3153 <li>
3154 <p><a class='existingWikiWord' href='/nlab/show/Grothendieck+constructio…
3155 </li>
3156
3157 <li>
3158 <p><a class='existingWikiWord' href='/nlab/show/adjoint+functor+theorem'…
3159 </li>
3160
3161 <li>
3162 <p><a class='existingWikiWord' href='/nlab/show/monadicity+theorem'>mona…
3163 </li>
3164
3165 <li>
3166 <p><a class='existingWikiWord' href='/nlab/show/adjoint+lifting+theorem'…
3167 </li>
3168
3169 <li>
3170 <p><a class='existingWikiWord' href='/nlab/show/Tannaka+duality'>Tannaka…
3171 </li>
3172
3173 <li>
3174 <p><a class='existingWikiWord' href='/nlab/show/Gabriel-Ulmer+duality'>G…
3175 </li>
3176
3177 <li>
3178 <p><a class='existingWikiWord' href='/nlab/show/small+object+argument'>s…
3179 </li>
3180
3181 <li>
3182 <p><a class='existingWikiWord' href='/nlab/show/Freyd-Mitchell+embedding…
3183 </li>
3184
3185 <li>
3186 <p><a class='existingWikiWord' href='/nlab/show/relation+between+type+th…
3187 </li>
3188 </ul>
3189
3190 <h2 id='extensions'>Extensions</h2>
3191
3192 <ul>
3193 <li>
3194 <p><a class='existingWikiWord' href='/nlab/show/sheaf+and+topos+theory'>…
3195 </li>
3196
3197 <li>
3198 <p><a class='existingWikiWord' href='/nlab/show/enriched+category+theory…
3199 </li>
3200
3201 <li>
3202 <p><a class='existingWikiWord' href='/nlab/show/higher+category+theory'>…
3203 </li>
3204 </ul>
3205
3206 <h2 id='applications'>Applications</h2>
3207
3208 <ul>
3209 <li><a class='existingWikiWord' href='/nlab/show/applications+of+%28high…
3210 </ul>
3211 <div>
3212 <p>
3213 <a href='/nlab/edit/category+theory+-+contents'>Edit this sidebar</a>
3214 </p>
3215 </div></div>
3216 </div>
3217 </div>
3218
3219 <h1 id='contents'>Contents</h1>
3220 <div class='maruku_toc'><ul><li><a href='#idea'>Idea</a></li><li><a href…
3221 <h2 id='idea'>Idea</h2>
3222
3223 <p>What is called <em>geometric realization of categories</em> is a <a c…
3224
3225 <p>By the <a class='existingWikiWord' href='/nlab/show/homotopy+hypothes…
3226
3227 <p>Therefore an equivalent perspective on geometric realization of categ…
3228
3229 <p>Geometric realization of categories has various good properties:</p>
3230
3231 <p>It sends <a class='existingWikiWord' href='/nlab/show/equivalence+of+…
3232
3233 <p>The existence of the <a class='existingWikiWord' href='/nlab/show/Tho…
3234
3235 <h2 id='definition'>Definition</h2>
3236
3237 <p>Write</p>
3238 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
3239 N \colon Cat \to sSet
3240
3241 </annotation></semantics></math></div>
3242 <p>for the <a href='nerve#NerveOfACategory'>nerve functor</a> from <a cl…
3243 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
3244 {\vert - \vert} : sSet \to Top
3245
3246 </annotation></semantics></math></div>
3247 <p>for the <a class='existingWikiWord' href='/nlab/show/geometric+realiz…
3248
3249 <p>The <em>geometric realization of categories</em> is the <a class='exi…
3250 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
3251 {\vert - \vert} \coloneqq {\vert N(-)\vert} \;\colon\; Cat \to Top
3252
3253 </annotation></semantics></math></div>
3254 <h2 id='properties'>Properties</h2>
3255
3256 <h3 id='ThomasonModelStructure'>Thomason model structure</h3>
3257
3258 <p>There is a <a class='existingWikiWord' href='/nlab/show/model+categor…
3259
3260 <p>The existence of the Thomas model structure implies that every <a cla…
3261
3262 <div class='num_defn' id='PosetOfSimplicesInNerveOfCategory'>
3263 <h6 id='definition_2'>Definition</h6>
3264
3265 <p>For <math class='maruku-mathml' display='inline' id='mathml_ea68c383f…
3266 </div>
3267
3268 <div class='num_prop'>
3269 <h6 id='proposition'>Proposition</h6>
3270
3271 <p>For every category <math class='maruku-mathml' display='inline' id='m…
3272 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
3273 {\vert N(\nabla \mathcal{C}) \vert} \simeq_{wh} {\vert \mathcal{C} \ve…
3274 \,.
3275
3276 </annotation></semantics></math></div></div>
3277
3278 <h3 id='recognizing_weak_equivalences_quillens_theorem_a_and_b'>Recogniz…
3279
3280 <p>Let <math class='maruku-mathml' display='inline' id='mathml_ea68c383f…
3281 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
3282 F \;\colon\; \mathcal{C} \longrightarrow \mathcal{D}
3283
3284 </annotation></semantics></math></div>
3285 <p>be a <a class='existingWikiWord' href='/nlab/show/functor'>functor</a…
3286
3287 <div class='num_theorem' id='QuillenTheoremA'>
3288 <h6 id='theorem'>Theorem</h6>
3289
3290 <p><strong>(<a href='#Quillen72'>Quillen 72</a>, theorem A)</strong></p>
3291
3292 <p>If for all <a class='existingWikiWord' href='/nlab/show/object'>objec…
3293 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
3294 {\vert N(F) \vert}
3295 \;\colon\;
3296 {\vert N(\mathcal{C}) \vert}
3297 \longrightarrow
3298 {\vert N(\mathcal{D}) \vert}
3299
3300 </annotation></semantics></math></div>
3301 <p>is a <a class='existingWikiWord' href='/nlab/show/weak+homotopy+equiv…
3302 </div>
3303
3304 <div class='num_theorem' id='QuillenTheoremB'>
3305 <h6 id='theorem_2'>Theorem</h6>
3306
3307 <p><strong>(<a href='#Quillen72'>Quillen 72</a> theorem B)</strong></p>
3308
3309 <p>If for all <a class='existingWikiWord' href='/nlab/show/object'>objec…
3310 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
3311 X
3312 \longrightarrow
3313 {\vert N(\mathcal{C}) \vert}
3314 \overset{\vert N(F) \vert }{\longrightarrow}
3315 {\vert N(\mathcal{D}) \vert}
3316 \,.
3317
3318 </annotation></semantics></math></div></div>
3319
3320 <p>As a consequence:</p>
3321
3322 <div class='num_prop'>
3323 <h6 id='proposition_2'>Proposition</h6>
3324
3325 <p><strong>(<a href='#McCord66'>McCord 66, theorem 6</a>, <a href='#Quil…
3326
3327 <p>Let <math class='maruku-mathml' display='inline' id='mathml_ea68c383f…
3328
3329 <p>If for each element/object <math class='maruku-mathml' display='inlin…
3330 </div>
3331
3332 <p>An alternative proof is given in (<a href='#Barmak10'>Barmak 10</a>).…
3333
3334 <h3 id='natural_transformations_and_homotopies'>Natural transformations …
3335
3336 <div class='num_prop' id='NaturalTrafoMapsToHomotopy'>
3337 <h6 id='proposition_3'>Proposition</h6>
3338
3339 <p>A <a class='existingWikiWord' href='/nlab/show/natural+transformation…
3340 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
3341 {|N(\eta)|} \colon {\vert N(F)\vert} \longrightarrow {\vert N(G) \vert}
3342 \,.
3343
3344 </annotation></semantics></math></div></div>
3345
3346 <div class='proof'>
3347 <h6 id='proof'>Proof</h6>
3348
3349 <p>The natural transformation is equivalently a functor of the form</p>
3350 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
3351 \eta \;\colon\; \mathcal{C} \times \{0 \to 1\} \to \mathcal{D}
3352
3353 </annotation></semantics></math></div>
3354 <p>out of the <a class='existingWikiWord' href='/nlab/show/product+categ…
3355
3356 <p>Since <a class='existingWikiWord' href='/nlab/show/geometric+realizat…
3357 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
3358 {\vert N( \mathcal{C} \times \{0,1\} ) \vert}
3359 \;\simeq_{iso}\;
3360 {\vert N(\mathcal{C}) \vert} \times {\vert N(\{0 \to 1\}) \vert}
3361
3362 </annotation></semantics></math></div>
3363 <p>But this is a <a class='existingWikiWord' href='/nlab/show/cylinder+o…
3364 </div>
3365
3366 <div class='num_cor' id='RealizationOfEquivalenceIsHomotopyEquivalence'>
3367 <h6 id='corollary'>Corollary</h6>
3368
3369 <p>An <a class='existingWikiWord' href='/nlab/show/equivalence+of+catego…
3370 </div>
3371
3372 <div class='num_remark'>
3373 <h6 id='remark'>Remark</h6>
3374
3375 <p>The statement still remains true for a pair of <a class='existingWiki…
3376 </div>
3377
3378 <div class='num_remark'>
3379 <h6 id='remark_2'>Remark</h6>
3380
3381 <p>Notice that the converse is far from true: Very different categories …
3382 </div>
3383
3384 <div class='num_cor' id='RealizationWithTerminalObjectIsContractible'>
3385 <h6 id='corollary_2'>Corollary</h6>
3386
3387 <p>If a <a class='existingWikiWord' href='/nlab/show/category'>category<…
3388 </div>
3389
3390 <div class='proof'>
3391 <h6 id='proof_2'>Proof</h6>
3392
3393 <p>Assume the case of a terminal object, the other case works <a class='…
3394
3395 <p>Then we have an equality of functors</p>
3396 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
3397 Id_* = (* \stackrel{\bottom}{\to} C \to *)
3398 \,,
3399
3400 </annotation></semantics></math></div>
3401 <p>where the first functor on the right picks the terminal object, and w…
3402 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
3403 Id_C \Rightarrow (C \to * \stackrel{\bottom}{\to} C)
3404
3405 </annotation></semantics></math></div>
3406 <p>whose components are the unique morphisms into the terminal object.</…
3407
3408 <p>By prop. <a class='maruku-ref' href='#NaturalTrafoMapsToHomotopy'>3</…
3409 </div>
3410
3411 <h3 id='behaviour_under_homotopy_colimits'>Behaviour under homotopy coli…
3412
3413 <div class='num_prop'>
3414 <h6 id='proposition_4'>Proposition</h6>
3415
3416 <p>For <math class='maruku-mathml' display='inline' id='mathml_ea68c383f…
3417 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
3418 {\vert N(F(-))\vert}
3419 \;\colon\;
3420 \mathcal{D}
3421 \overset{F}{\longrightarrow}
3422 Cat
3423 \stackrel{\vert N(-) \vert}{\to}
3424 Top
3425
3426 </annotation></semantics></math></div>
3427 <p>be its postcomposition with geometric realization of categories</p>
3428
3429 <p>Then we have a <a class='existingWikiWord' href='/nlab/show/weak+homo…
3430 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
3431 {\left\vert N\left(\int F \right) \right\vert}
3432 \simeq
3433 hocolim {\vert F(N(-)) \vert}
3434
3435 </annotation></semantics></math></div>
3436 <p>exhibiting the <a class='existingWikiWord' href='/nlab/show/homotopy+…
3437 </div>
3438
3439 <p>This is due to (<a href='#Thomason79'>Thomason 79</a>).</p>
3440
3441 <h2 id='related_concepts'>Related concepts</h2>
3442
3443 <ul>
3444 <li>
3445 <p><a class='existingWikiWord' href='/nlab/show/geometric+realization'>g…
3446
3447 <ul>
3448 <li><strong>of categories</strong>, <a class='existingWikiWord' href='/n…
3449 </ul>
3450 </li>
3451 </ul>
3452
3453 <h2 id='references'>References</h2>
3454
3455 <h3 id='general'>General</h3>
3456
3457 <p>For general references see also <em><a class='existingWikiWord' href=…
3458
3459 <h3 id='quillens_theorems_a_and_b'>Quillen’s theorems A and B</h3>
3460
3461 <p>The original articles are</p>
3462
3463 <ul>
3464 <li id='McCord66'>
3465 <p><a class='existingWikiWord' href='/nlab/show/Michael+C.+McCord'>Micha…
3466 </li>
3467
3468 <li id='Quillen72'>
3469 <p><a class='existingWikiWord' href='/nlab/show/Daniel+Quillen'>Daniel Q…
3470 </li>
3471
3472 <li id='Quillen78'>
3473 <p><a class='existingWikiWord' href='/nlab/show/Daniel+Quillen'>Daniel Q…
3474 </li>
3475 </ul>
3476
3477 <p>The geometric realization of <a class='existingWikiWord' href='/nlab/…
3478
3479 <ul>
3480 <li id='Thomason79'><a class='existingWikiWord' href='/nlab/show/Robert+…
3481 </ul>
3482
3483 <p>Review is in</p>
3484
3485 <ul>
3486 <li id='Barmak10'><a class='existingWikiWord' href='/nlab/show/Jonathan+…
3487 </ul>
3488
3489 <p>Further development includes</p>
3490
3491 <ul>
3492 <li>
3493 <p><a class='existingWikiWord' href='/nlab/show/Clark+Barwick'>Clark Bar…
3494 </li>
3495
3496 <li>
3497 <p><a class='existingWikiWord' href='/nlab/show/David+Michael+Roberts'>D…
3498 </li>
3499 </ul>
3500
3501 <p>
3502 </p>
3503
3504 <p>
3505
3506
3507
3508
3509
3510
3511
3512 </p> </div>
3513 </content>
3514 </entry>
3515 <entry>
3516 <title type="html">Borel model structure</title>
3517 <link rel="alternate" type="application/xhtml+xml" href="https://nca…
3518 <updated>2021-07-01T16:26:36Z</updated>
3519 <published>2014-04-15T05:41:15Z</published>
3520 <id>tag:ncatlab.org,2014-04-15:nLab,Borel+model+structure</id>
3521 <author>
3522 <name>Urs Schreiber</name>
3523 </author>
3524 <content type="xhtml" xml:base="https://ncatlab.org/nlab/show/Borel+…
3525 <div xmlns="http://www.w3.org/1999/xhtml">
3526 <div class='rightHandSide'>
3527 <div class='toc clickDown' tabindex='0'>
3528 <h3 id='context'>Context</h3>
3529
3530 <h4 id='model_category_theory'>Model category theory</h4>
3531
3532 <div class='hide'>
3533 <p><strong><a class='existingWikiWord' href='/nlab/show/model+category'>…
3534
3535 <h2 id='definitions'>Definitions</h2>
3536
3537 <ul>
3538 <li>
3539 <p><a class='existingWikiWord' href='/nlab/show/category+with+weak+equiv…
3540 </li>
3541
3542 <li>
3543 <p><a class='existingWikiWord' href='/nlab/show/weak+factorization+syste…
3544 </li>
3545
3546 <li>
3547 <p><a class='existingWikiWord' href='/nlab/show/homotopy+%28as+an+operat…
3548
3549 <ul>
3550 <li><a class='existingWikiWord' href='/nlab/show/homotopy+category'>homo…
3551 </ul>
3552 </li>
3553
3554 <li>
3555 <p><a class='existingWikiWord' href='/nlab/show/small+object+argument'>s…
3556 </li>
3557
3558 <li>
3559 <p><a class='existingWikiWord' href='/nlab/show/resolution'>resolution</…
3560 </li>
3561 </ul>
3562
3563 <h2 id='morphisms'>Morphisms</h2>
3564
3565 <ul>
3566 <li>
3567 <p><a class='existingWikiWord' href='/nlab/show/Quillen+adjunction'>Quil…
3568
3569 <ul>
3570 <li>
3571 <p><a class='existingWikiWord' href='/nlab/show/Quillen+equivalence'>Qui…
3572 </li>
3573
3574 <li>
3575 <p><a class='existingWikiWord' href='/nlab/show/Quillen+bifunctor'>Quill…
3576 </li>
3577
3578 <li>
3579 <p><a class='existingWikiWord' href='/nlab/show/derived+functor'>derived…
3580 </li>
3581 </ul>
3582 </li>
3583 </ul>
3584
3585 <h2 id='universal_constructions'>Universal constructions</h2>
3586
3587 <ul>
3588 <li>
3589 <p><a class='existingWikiWord' href='/nlab/show/homotopy+Kan+extension'>…
3590 </li>
3591
3592 <li>
3593 <p><a class='existingWikiWord' href='/nlab/show/homotopy+limit'>homotopy…
3594 </li>
3595
3596 <li>
3597 <p><a class='existingWikiWord' href='/nlab/show/Bousfield-Kan+map'>Bousf…
3598 </li>
3599 </ul>
3600
3601 <h2 id='refinements'>Refinements</h2>
3602
3603 <ul>
3604 <li>
3605 <p><a class='existingWikiWord' href='/nlab/show/monoidal+model+category'…
3606
3607 <ul>
3608 <li><a class='existingWikiWord' href='/nlab/show/monoidal+Quillen+adjunc…
3609 </ul>
3610 </li>
3611
3612 <li>
3613 <p><a class='existingWikiWord' href='/nlab/show/enriched+model+category'…
3614
3615 <ul>
3616 <li><a class='existingWikiWord' href='/nlab/show/enriched+Quillen+adjunc…
3617 </ul>
3618 </li>
3619
3620 <li>
3621 <p><a class='existingWikiWord' href='/nlab/show/simplicial+model+categor…
3622
3623 <ul>
3624 <li><a class='existingWikiWord' href='/nlab/show/simplicial+Quillen+adju…
3625 </ul>
3626 </li>
3627
3628 <li>
3629 <p><a class='existingWikiWord' href='/nlab/show/cofibrantly+generated+mo…
3630
3631 <ul>
3632 <li>
3633 <p><a class='existingWikiWord' href='/nlab/show/combinatorial+model+cate…
3634 </li>
3635
3636 <li>
3637 <p><a class='existingWikiWord' href='/nlab/show/cellular+model+category'…
3638 </li>
3639 </ul>
3640 </li>
3641
3642 <li>
3643 <p><a class='existingWikiWord' href='/nlab/show/algebraic+model+category…
3644 </li>
3645
3646 <li>
3647 <p><a class='existingWikiWord' href='/nlab/show/compactly+generated+mode…
3648 </li>
3649
3650 <li>
3651 <p><a class='existingWikiWord' href='/nlab/show/proper+model+category'>p…
3652 </li>
3653
3654 <li>
3655 <p><a class='existingWikiWord' href='/nlab/show/cartesian+model+category…
3656 </li>
3657
3658 <li>
3659 <p><a class='existingWikiWord' href='/nlab/show/stable+model+category'>s…
3660 </li>
3661 </ul>
3662
3663 <h2 id='producing_new_model_structures'>Producing new model structures</…
3664
3665 <ul>
3666 <li>
3667 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+funct…
3668
3669 <ul>
3670 <li><a class='existingWikiWord' href='/nlab/show/Reedy+model+structure'>…
3671 </ul>
3672 </li>
3673
3674 <li>
3675 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+an+ov…
3676 </li>
3677
3678 <li>
3679 <p><a class='existingWikiWord' href='/nlab/show/Bousfield+localization+o…
3680 </li>
3681
3682 <li>
3683 <p><a class='existingWikiWord' href='/nlab/show/transferred+model+struct…
3684
3685 <ul>
3686 <li><a class='existingWikiWord' href='/nlab/show/model+structure+on+alge…
3687 </ul>
3688 </li>
3689
3690 <li>
3691 <p><a class='existingWikiWord' href='/nlab/show/Grothendieck+constructio…
3692 </li>
3693 </ul>
3694
3695 <h2 id='presentation_of_categories'>Presentation of <math class='maruku-…
3696
3697 <ul>
3698 <li>
3699 <p><a class='existingWikiWord' href='/nlab/show/%28infinity%2C1%29-categ…
3700 </li>
3701
3702 <li>
3703 <p><a class='existingWikiWord' href='/nlab/show/simplicial+localization'…
3704 </li>
3705
3706 <li>
3707 <p><a class='existingWikiWord' href='/nlab/show/%28infinity%2C1%29-categ…
3708 </li>
3709
3710 <li>
3711 <p><a class='existingWikiWord' href='/nlab/show/locally+presentable+%28i…
3712 </li>
3713 </ul>
3714
3715 <h2 id='model_structures'>Model structures</h2>
3716
3717 <ul>
3718 <li><a class='existingWikiWord' href='/nlab/show/Cisinski+model+structur…
3719 </ul>
3720
3721 <h3 id='for_groupoids'>for <math class='maruku-mathml' display='inline' …
3722
3723 <p><a class='existingWikiWord' href='/nlab/show/model+structure+for+infi…
3724
3725 <ul>
3726 <li>
3727 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+topol…
3728
3729 <ul>
3730 <li>
3731 <p><a class='existingWikiWord' href='/nlab/show/classical+model+structur…
3732 </li>
3733
3734 <li>
3735 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+Delta…
3736 </li>
3737
3738 <li>
3739 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+diffe…
3740 </li>
3741
3742 <li>
3743 <p><a class='existingWikiWord' href='/nlab/show/Str%C3%B8m+model+structu…
3744 </li>
3745 </ul>
3746 </li>
3747
3748 <li>
3749 <p><a class='existingWikiWord' href='/nlab/show/Thomason+model+structure…
3750 </li>
3751
3752 <li>
3753 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+presh…
3754 </li>
3755
3756 <li>
3757 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+simpl…
3758
3759 <ul>
3760 <li>
3761 <p><a class='existingWikiWord' href='/nlab/show/classical+model+structur…
3762 </li>
3763
3764 <li>
3765 <p><a class='existingWikiWord' href='/nlab/show/constructive+model+struc…
3766 </li>
3767
3768 <li>
3769 <p><a class='existingWikiWord' href='/nlab/show/model+structure+for+left…
3770 </li>
3771 </ul>
3772 </li>
3773
3774 <li>
3775 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+simpl…
3776 </li>
3777
3778 <li>
3779 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+cubic…
3780 </li>
3781
3782 <li>
3783 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+stric…
3784 </li>
3785
3786 <li>
3787 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+chain…
3788
3789 <p>related by the <a class='existingWikiWord' href='/nlab/show/Dold-Kan+…
3790 </li>
3791
3792 <li>
3793 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+cosim…
3794 </li>
3795 </ul>
3796
3797 <h3 id='for_rational_groupoids'>for rational <math class='maruku-mathml'…
3798
3799 <ul>
3800 <li>
3801 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+dg-al…
3802 </li>
3803
3804 <li>
3805 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+equiv…
3806
3807 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+equiv…
3808 </li>
3809 </ul>
3810
3811 <h3 id='for_groupoids_2'>for <math class='maruku-mathml' display='inline…
3812
3813 <ul>
3814 <li>
3815 <p><a class='existingWikiWord' href='/nlab/show/model+structure+for+homo…
3816 </li>
3817
3818 <li>
3819 <p><a class='existingWikiWord' href='/nlab/show/canonical+model+structur…
3820 </li>
3821 </ul>
3822
3823 <h3 id='for_groups'>for <math class='maruku-mathml' display='inline' id=…
3824
3825 <ul>
3826 <li>
3827 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+simpl…
3828 </li>
3829
3830 <li>
3831 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+reduc…
3832 </li>
3833 </ul>
3834
3835 <h3 id='for_algebras'>for <math class='maruku-mathml' display='inline' i…
3836
3837 <h4 id='general'>general</h4>
3838
3839 <ul>
3840 <li>
3841 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+monoi…
3842 </li>
3843
3844 <li>
3845 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+simpl…
3846 </li>
3847
3848 <li>
3849 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+algeb…
3850 </li>
3851
3852 <li>
3853 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+algeb…
3854 </li>
3855 </ul>
3856
3857 <h4 id='specific'>specific</h4>
3858
3859 <ul>
3860 <li>
3861 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+dg-al…
3862 </li>
3863
3864 <li>
3865 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+diffe…
3866 </li>
3867
3868 <li>
3869 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+dg-al…
3870
3871 <ul>
3872 <li>
3873 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+dg-al…
3874
3875 <p>related by the <a class='existingWikiWord' href='/nlab/show/monoidal+…
3876 </li>
3877
3878 <li>
3879 <p><a class='existingWikiWord' href='/nlab/show/model+structure+for+L-in…
3880 </li>
3881 </ul>
3882 </li>
3883
3884 <li>
3885 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+dg-mo…
3886 </li>
3887 </ul>
3888
3889 <h3 id='for_stablespectrum_objects'>for stable/spectrum objects</h3>
3890
3891 <ul>
3892 <li>
3893 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+spect…
3894 </li>
3895
3896 <li>
3897 <p><a class='existingWikiWord' href='/nlab/show/model+structure+for+ring…
3898 </li>
3899
3900 <li>
3901 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+presh…
3902 </li>
3903 </ul>
3904
3905 <h3 id='for_categories'>for <math class='maruku-mathml' display='inline'…
3906
3907 <ul>
3908 <li>
3909 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+relat…
3910 </li>
3911
3912 <li>
3913 <p><a class='existingWikiWord' href='/nlab/show/model+structure+for+quas…
3914 </li>
3915
3916 <li>
3917 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+sSet-…
3918 </li>
3919
3920 <li>
3921 <p><a class='existingWikiWord' href='/nlab/show/model+structure+for+comp…
3922 </li>
3923
3924 <li>
3925 <p><a class='existingWikiWord' href='/nlab/show/model+structure+for+Cart…
3926 </li>
3927 </ul>
3928
3929 <h3 id='for_stable_categories'>for stable <math class='maruku-mathml' di…
3930
3931 <ul>
3932 <li><a class='existingWikiWord' href='/nlab/show/model+structure+on+dg-c…
3933 </ul>
3934
3935 <h3 id='for_operads'>for <math class='maruku-mathml' display='inline' id…
3936
3937 <ul>
3938 <li>
3939 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+opera…
3940
3941 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+algeb…
3942 </li>
3943
3944 <li>
3945 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+dendr…
3946 </li>
3947 </ul>
3948
3949 <h3 id='for_categories_2'>for <math class='maruku-mathml' display='inlin…
3950
3951 <ul>
3952 <li>
3953 <p><a class='existingWikiWord' href='/nlab/show/Theta-space'>for (n,r)-c…
3954 </li>
3955
3956 <li>
3957 <p><a class='existingWikiWord' href='/nlab/show/model+structure+for+weak…
3958 </li>
3959
3960 <li>
3961 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+cellu…
3962 </li>
3963
3964 <li>
3965 <p><a class='existingWikiWord' href='/nlab/show/canonical+model+structur…
3966 </li>
3967
3968 <li>
3969 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+stric…
3970 </li>
3971 </ul>
3972
3973 <h3 id='for_sheaves__stacks'>for <math class='maruku-mathml' display='in…
3974
3975 <ul>
3976 <li>
3977 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+homot…
3978
3979 <ul>
3980 <li>
3981 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+simpl…
3982
3983 <p><a class='existingWikiWord' href='/nlab/show/global+model+structure+o…
3984
3985 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+simpl…
3986
3987 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+presh…
3988
3989 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+sSet-…
3990 </li>
3991 </ul>
3992 </li>
3993
3994 <li>
3995 <p><a class='existingWikiWord' href='/nlab/show/model+structure+for+%282…
3996 </li>
3997 </ul>
3998 <div>
3999 <p>
4000 <a href='/nlab/edit/model+category+theory+-+contents'>Edit this sideba…
4001 </p>
4002 </div></div>
4003
4004 <h4 id='group_theory'>Group Theory</h4>
4005
4006 <div class='hide'>
4007 <p><strong><a class='existingWikiWord' href='/nlab/show/group+theory'>gr…
4008
4009 <ul>
4010 <li><a class='existingWikiWord' href='/nlab/show/group'>group</a>, <a cl…
4011
4012 <li><a class='existingWikiWord' href='/nlab/show/group+object'>group obj…
4013
4014 <li><a class='existingWikiWord' href='/nlab/show/abelian+group'>abelian …
4015
4016 <li><a class='existingWikiWord' href='/nlab/show/action'>group action</a…
4017
4018 <li><a class='existingWikiWord' href='/nlab/show/representation'>represe…
4019
4020 <li><a class='existingWikiWord' href='/nlab/show/progroup'>progroup</a><…
4021
4022 <li><a class='existingWikiWord' href='/nlab/show/homogeneous+space'>homo…
4023 </ul>
4024
4025 <h3 id='classical_groups'>Classical groups</h3>
4026
4027 <ul>
4028 <li>
4029 <p><a class='existingWikiWord' href='/nlab/show/general+linear+group'>ge…
4030 </li>
4031
4032 <li>
4033 <p><a class='existingWikiWord' href='/nlab/show/unitary+group'>unitary g…
4034
4035 <ul>
4036 <li><a class='existingWikiWord' href='/nlab/show/special+unitary+group'>…
4037 </ul>
4038 </li>
4039
4040 <li>
4041 <p><a class='existingWikiWord' href='/nlab/show/orthogonal+group'>orthog…
4042
4043 <ul>
4044 <li><a class='existingWikiWord' href='/nlab/show/special+orthogonal+grou…
4045 </ul>
4046 </li>
4047
4048 <li>
4049 <p><a class='existingWikiWord' href='/nlab/show/symplectic+group'>symple…
4050 </li>
4051 </ul>
4052
4053 <h3 id='finite_groups'>Finite groups</h3>
4054
4055 <ul>
4056 <li>
4057 <p><a class='existingWikiWord' href='/nlab/show/finite+group'>finite gro…
4058 </li>
4059
4060 <li>
4061 <p><a class='existingWikiWord' href='/nlab/show/symmetric+group'>symmetr…
4062 </li>
4063
4064 <li>
4065 <p><a class='existingWikiWord' href='/nlab/show/classification+of+finite…
4066 </li>
4067
4068 <li>
4069 <p><a class='existingWikiWord' href='/nlab/show/sporadic+finite+simple+g…
4070
4071 <ul>
4072 <li><a class='existingWikiWord' href='/nlab/show/Monster+group'>Monster …
4073 </ul>
4074 </li>
4075 </ul>
4076
4077 <h3 id='group_schemes'>Group schemes</h3>
4078
4079 <ul>
4080 <li><a class='existingWikiWord' href='/nlab/show/algebraic+group'>algebr…
4081
4082 <li><a class='existingWikiWord' href='/nlab/show/abelian+variety'>abelia…
4083 </ul>
4084
4085 <h3 id='topological_groups'>Topological groups</h3>
4086
4087 <ul>
4088 <li>
4089 <p><a class='existingWikiWord' href='/nlab/show/topological+group'>topol…
4090 </li>
4091
4092 <li>
4093 <p><a class='existingWikiWord' href='/nlab/show/compact+topological+grou…
4094 </li>
4095
4096 <li>
4097 <p><a class='existingWikiWord' href='/nlab/show/maximal+compact+subgroup…
4098 </li>
4099
4100 <li>
4101 <p><a class='existingWikiWord' href='/nlab/show/string+group'>string gro…
4102 </li>
4103 </ul>
4104
4105 <h3 id='lie_groups'>Lie groups</h3>
4106
4107 <ul>
4108 <li>
4109 <p><a class='existingWikiWord' href='/nlab/show/Lie+group'>Lie group</a>…
4110 </li>
4111
4112 <li>
4113 <p><a class='existingWikiWord' href='/nlab/show/compact+Lie+group'>compa…
4114 </li>
4115
4116 <li>
4117 <p><a class='existingWikiWord' href='/nlab/show/Kac-Moody+group'>Kac-Moo…
4118 </li>
4119 </ul>
4120
4121 <h3 id='superlie_groups'>Super-Lie groups</h3>
4122
4123 <ul>
4124 <li>
4125 <p><a class='existingWikiWord' href='/nlab/show/supergroup'>super Lie gr…
4126 </li>
4127
4128 <li>
4129 <p><a class='existingWikiWord' href='/nlab/show/super+Euclidean+group'>s…
4130 </li>
4131 </ul>
4132
4133 <h3 id='higher_groups'>Higher groups</h3>
4134
4135 <ul>
4136 <li>
4137 <p><a class='existingWikiWord' href='/nlab/show/2-group'>2-group</a></p>
4138
4139 <ul>
4140 <li><a class='existingWikiWord' href='/nlab/show/crossed+module'>crossed…
4141 </ul>
4142 </li>
4143
4144 <li>
4145 <p><a class='existingWikiWord' href='/nlab/show/n-group'>n-group</a></p>
4146 </li>
4147
4148 <li>
4149 <p><a class='existingWikiWord' href='/nlab/show/infinity-group'>∞-grou…
4150
4151 <ul>
4152 <li>
4153 <p><a class='existingWikiWord' href='/nlab/show/simplicial+group'>simpli…
4154 </li>
4155
4156 <li>
4157 <p><a class='existingWikiWord' href='/nlab/show/crossed+complex'>crossed…
4158 </li>
4159
4160 <li>
4161 <p><a class='existingWikiWord' href='/nlab/show/k-tuply+groupal+n-groupo…
4162 </li>
4163
4164 <li>
4165 <p><a class='existingWikiWord' href='/nlab/show/spectrum'>spectrum</a></…
4166 </li>
4167 </ul>
4168 </li>
4169
4170 <li>
4171 <p><a class='existingWikiWord' href='/nlab/show/circle+n-group'>circle n…
4172 </li>
4173 </ul>
4174
4175 <h3 id='cohomology_and_extensions'>Cohomology and Extensions</h3>
4176
4177 <ul>
4178 <li>
4179 <p><a class='existingWikiWord' href='/nlab/show/group+cohomology'>group …
4180 </li>
4181
4182 <li>
4183 <p><a class='existingWikiWord' href='/nlab/show/group+extension'>group e…
4184 </li>
4185
4186 <li>
4187 <p><a class='existingWikiWord' href='/nlab/show/infinity-group+extension…
4188 </li>
4189 </ul>
4190
4191 <h3 id='_related_concepts'>Related concepts</h3>
4192
4193 <ul>
4194 <li><a class='existingWikiWord' href='/nlab/show/quantum+group'>quantum …
4195 </ul>
4196 <div>
4197 <p>
4198 <a href='/nlab/edit/group+theory+-+contents'>Edit this sidebar</a>
4199 </p>
4200 </div></div>
4201 </div>
4202 </div>
4203
4204 <h1 id='contents'>Contents</h1>
4205 <div class='maruku_toc'><ul><li><a href='#idea'>Idea</a></li><li><a href…
4206 <h2 id='idea'>Idea</h2>
4207
4208 <p>Given a <a class='existingWikiWord' href='/nlab/show/simplicial+group…
4209
4210 <p>In the context of <a class='existingWikiWord' href='/nlab/show/equiva…
4211
4212 <h2 id='definition'>Definition</h2>
4213
4214 <p>\begin{defn}\label{BorelModelStructure}</p>
4215
4216 <p>For <math class='maruku-mathml' display='inline' id='mathml_6bd24f229…
4217
4218 <ul>
4219 <li>
4220 <p><math class='maruku-mathml' display='inline' id='mathml_6bd24f22919d9…
4221 </li>
4222
4223 <li>
4224 <p><math class='maruku-mathml' display='inline' id='mathml_6bd24f22919d9…
4225 </li>
4226
4227 <li>
4228 <p><math class='maruku-mathml' display='inline' id='mathml_6bd24f22919d9…
4229 </li>
4230 </ul>
4231
4232 <p>This is the <math class='maruku-mathml' display='inline' id='mathml_6…
4233
4234 <p>\end{defn}</p>
4235
4236 <h2 id='properties'>Properties</h2>
4237
4238 <h3 id='CofibrantReplacementAndHomotopyQuotientsFixedPoints'>Cofibrant r…
4239
4240 <p>\begin{prop}\label{CofibrationsOfSimplicialActions} <strong>(cofibrat…
4241
4242 <ol>
4243 <li>
4244 <p>the underlying morphism of <a class='existingWikiWord' href='/nlab/sh…
4245 </li>
4246
4247 <li>
4248 <p>the <math class='maruku-mathml' display='inline' id='mathml_6bd24f229…
4249 </li>
4250 </ol>
4251
4252 <p>\end{prop}</p>
4253
4254 <p>This is (<a href='#DDK80'>DDK 80, Prop. 2.2. (ii)</a>, <a href='#Guil…
4255
4256 <p>\begin{remark} In particular this means that an object is <a class='e…
4257
4258 <p>Hence <a class='existingWikiWord' href='/nlab/show/fibrant+replacemen…
4259
4260 <p>\begin{remark} It follows that for <math class='maruku-mathml' displa…
4261 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4262 R Hom_G(X,A)
4263
4264 </annotation></semantics></math></div>
4265 <p>models the Borel <math class='maruku-mathml' display='inline' id='mat…
4266
4267 <p>In particular,if <math class='maruku-mathml' display='inline' id='mat…
4268
4269 <ol>
4270 <li>
4271 <p>if the <math class='maruku-mathml' display='inline' id='mathml_6bd24f…
4272 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4273 R Hom_G(X,A)
4274 \simeq
4275 Hom_G(W G \times X , A)
4276 \simeq
4277 Hom(W G \times_G X, A)
4278
4279 </annotation></semantics></math></div>
4280 <p>is equivalently maps of <a class='existingWikiWord' href='/nlab/show/…
4281 </li>
4282
4283 <li>
4284 <p>if <math class='maruku-mathml' display='inline' id='mathml_6bd24f2291…
4285 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4286 R Hom_G(X,A)
4287 \simeq
4288 Hom_G(W G, A)
4289 \simeq
4290 Hom(\overline{W} G , A)
4291 \simeq
4292 A^{h G}
4293
4294 </annotation></semantics></math></div>
4295 <p>is the <a class='existingWikiWord' href='/nlab/show/homotopy+fixed+po…
4296 </li>
4297 </ol>
4298
4299 <p>\end{remark}</p>
4300
4301 <h3 id='RelationToSliceOverSimplicialClassifyingSpace'>Relation to the s…
4302
4303 <p>\begin{prop}\label{QuillenEquivalenceToSliceOverSimplicialClassifying…
4304 <div class='maruku-equation' id='eq:QuillenAdjunctionWithSliceOverSimpli…
4305
4306 G_\bullet Acts(sSet)_{proj}
4307 \underoverset
4308 {\underset{ \big((-) \times W G\big)/G }{\longrightarrow}}
4309 {\overset{ (-) \times_{\overline{W}G} W G }{\longleftarrow}}
4310 {\bot}
4311 sSet_{/\overline{W}G}
4312
4313 </annotation></semantics></math></div>
4314 <p>which constitute a <a class='existingWikiWord' href='/nlab/show/simpl…
4315
4316 <p>\end{prop}</p>
4317
4318 <p>(<a href='#DDK80'>DDK 80, Prop. 2.3, Prop. 2.4</a>) Here:</p>
4319
4320 <ul>
4321 <li>
4322 <p>the <a class='existingWikiWord' href='/nlab/show/right+adjoint'>right…
4323 </li>
4324
4325 <li>
4326 <p>the <a class='existingWikiWord' href='/nlab/show/left+adjoint'>left a…
4327 </li>
4328 </ul>
4329
4330 <p>In fact, these are <a class='existingWikiWord' href='/nlab/show/SimpS…
4331
4332 <p>This kind of relation is discussed in more detail at <em><a class='ex…
4333
4334 <p>\begin{remark}\label{sSetEnrichmentOfAdjunctionToSliceOverSimpClassSp…
4335
4336 <p>The remaining observation that we have a <a class='existingWikiWord' …
4337 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4338 \big[
4339 X \times_{\overline{W}G} W G,
4340 \,
4341 V
4342 \big]
4343 \;\simeq\;
4344 \big[
4345 X,
4346 \,
4347 (V \times W G)/G
4348 \big]
4349
4350 </annotation></semantics></math></div>
4351 <p>hence</p>
4352 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4353 Hom
4354 \Big(
4355 \big( X \times_{\overline{W}G} W G \big) \times \Delta[\bullet],
4356 \,
4357 V
4358 \Big)
4359 \;\simeq\;
4360 Hom
4361 \big(
4362 X \times \Delta[\bullet],
4363 \,
4364 (V \times W G)/G
4365 \big)
4366
4367 </annotation></semantics></math></div>
4368 <p>follows from the plain adjunction and the natural isomorphism</p>
4369 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4370 (X \times_{\overline{W}G} W G) \times \Delta[\bullet]
4371 \;\simeq\;
4372 (X \times \Delta[\bullet]) \times_{\overline{W}G} W G
4373 \,,
4374
4375 </annotation></semantics></math></div>
4376 <p>which, in turn, follows, for instance, via the <a class='existingWiki…
4377
4378 <p>\begin{tikzcd} { { (X \times_{\overline{W}G} W G) \times \Delta[k] } …
4379
4380 <p>\end{remark}</p>
4381
4382 <h3 id='RelationToModelStructureOnPlainSimplicialSets'>Relation to the m…
4383
4384 <p>For <math class='maruku-mathml' display='inline' id='mathml_6bd24f229…
4385
4386 <p>\begin{proposition}\label{CofreeAction} <strong>(underlying simplicia…
4387
4388 <p>Its <a class='existingWikiWord' href='/nlab/show/right+adjoint'>right…
4389 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4390 sSet
4391 \underoverset
4392 {\underset{ \;\;\; [\mathcal{G},-] \;\;\; }{\longrightarrow}}
4393 {\overset{ \;\;\; undrl \;\;\; }{\longleftarrow}}
4394 {\bot}
4395 \mathcal{G}Actions(sSet)
4396
4397 </annotation></semantics></math></div>
4398 <p>sends <math class='maruku-mathml' display='inline' id='mathml_6bd24f2…
4399
4400 <ul>
4401 <li>
4402 <p>the simplicial set</p>
4403 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4404 [\mathcal{G},\mathcal{X}]
4405 \;\coloneqq\;
4406 Hom_{sSet}\big( \mathcal{G} \times \Delta[\bullet], \mathcal{X}\big)
4407 \;\;\;
4408 \in
4409 sSet
4410
4411 </annotation></semantics></math></div></li>
4412
4413 <li>
4414 <p>equipped with the <math class='maruku-mathml' display='inline' id='ma…
4415 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4416 \mathcal{G} \times [\mathcal{G},\mathcal{X}]
4417 \overset{ (-) \cdot (-) }{\longrightarrow}
4418 \mathcal{G}
4419
4420 </annotation></semantics></math></div>
4421 <p>which in degree <math class='maruku-mathml' display='inline' id='math…
4422 <div class='maruku-equation' id='eq:CofreeSimplicialActionComponentFunct…
4423
4424 Hom(\Delta[n], \mathcal{G})
4425 \,\times\,
4426 Hom
4427 \big(
4428 \mathcal{G} \times \Delta[n],
4429 \,
4430 \mathcal{X}
4431 \big)
4432 \longrightarrow
4433 Hom
4434 \big(
4435 \mathcal{G} \times \Delta[n],
4436 \,
4437 \mathcal{X}
4438 \big)
4439
4440 </annotation></semantics></math></div>
4441 <p>that sends</p>
4442 <div class='maruku-equation' id='eq:CofreeSimplicialActionInComponents'>…
4443
4444 \begin{aligned}
4445 &amp;
4446 \Big(
4447 \Delta[n] \overset{g_n}{\to} \mathcal{G},
4448 \;
4449 \mathcal{G}\times \Delta[n]
4450 \overset{\phi}{\to}
4451 \mathcal{X},
4452 \Big)
4453 \\
4454 \;\;\mapsto\;\;
4455 &amp;
4456 \Big(
4457 \mathcal{G} \times \Delta[n]
4458 \overset{id \times diag}{\longrightarrow}
4459 \mathcal{G} \times \Delta[n] \times \Delta[n]
4460 \overset{ id \times g_n \times id }{\longrightarrow}
4461 \mathcal{G} \times \mathcal{G} \times \Delta[n]
4462 \overset{(-)\cdot(-) \times id}{\to}
4463 \mathcal{G} \times \Delta[n]
4464 \overset{\phi}{\to}
4465 \mathcal{X}
4466 \Big)
4467 \end{aligned}
4468
4469 </annotation></semantics></math></div></li>
4470 </ul>
4471
4472 <p>\end{proposition}</p>
4473
4474 <p>Here and in the following proof we make free use of the <a class='exi…
4475 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4476 Hom_{sSet}(\Delta[n], \mathcal{S}) \;\simeq\; \mathcal{S}_n
4477
4478 </annotation></semantics></math></div>
4479 <p>for any <a class='existingWikiWord' href='/nlab/show/simplicial+set'>…
4480
4481 <p>\begin{proof}</p>
4482
4483 <p>We already know from Def. \ref{BorelModelStructure} that <math class=…
4484
4485 <p>The idea of the existence of the <a class='existingWikiWord' href='/n…
4486
4487 <p>To check that <a class='maruku-eqref' href='#eq:CofreeSimplicialActio…
4488 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4489 \big\{
4490 \mathcal{P}
4491 \overset{\;\;\phi_{(-)}\;\;}{\longrightarrow}
4492 [\mathcal{G}, \mathcal{X}]
4493 \big\}
4494 \;\;\;\overset{ \;\; \widetilde{(-)} \;\; }{\leftrightarrow}\;\;\;
4495 \big\{
4496 undrl(\mathcal{P})
4497 \overset{\;\; {\widetilde \phi}_{(-)} \;\; }{\longrightarrow}
4498 \mathcal{X}
4499 \big\}
4500 \,.
4501
4502 </annotation></semantics></math></div>
4503 <p>So given</p>
4504 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4505 \phi_{(-)}
4506 \;\colon\;
4507 p_n
4508 \mapsto
4509 \big(
4510 \phi_{p_n}
4511 \;\colon\;
4512 \mathcal{G} \times \Delta[n] \to \mathcal{X}
4513 \big)
4514
4515 </annotation></semantics></math></div>
4516 <p>on the left, define</p>
4517 <div class='maruku-equation' id='eq:AdjunctOfHomomorphismToCofreeSimplic…
4518
4519 \widetilde \phi_{(-)}
4520 \;\colon\;
4521 p_n
4522 \mapsto
4523 \phi_{p_n}(e_n, \sigma_n)
4524 \;\in\;
4525 \mathcal{X}_n
4526 \,,
4527
4528 </annotation></semantics></math></div>
4529 <p>where <math class='maruku-mathml' display='inline' id='mathml_6bd24f2…
4530
4531 <p>It is clear that this is a <a class='existingWikiWord' href='/nlab/sh…
4532
4533 <p>To that end, observe for any <math class='maruku-mathml' display='inl…
4534 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4535 \begin{aligned}
4536 \phi_{p_n}(g_n, \sigma_n)
4537 &amp; \;=\;
4538 \phi_{p_n}( e_n \cdot g_n, \sigma_n )
4539 \\
4540 &amp; \;=\;
4541 \big(
4542 g_n \cdot \phi_{p_n}
4543 \big)
4544 ( e_n, \sigma_n )
4545 \\
4546 &amp; \;=\;
4547 \phi_{ g_n \cdot p_n }
4548 (e_n, \sigma_n)
4549 \\
4550 &amp; \;=\;
4551 {\widetilde \phi}_{g_n \cdot p_n}
4552 \end{aligned}
4553
4554 </annotation></semantics></math></div>
4555 <p>Here:</p>
4556
4557 <ul>
4558 <li>
4559 <p>the first step is the unit law in the component group <math class='ma…
4560 </li>
4561
4562 <li>
4563 <p>the second step uses the definition <a class='maruku-eqref' href='#eq…
4564 </li>
4565
4566 <li>
4567 <p>the third step is the assumption that <math class='maruku-mathml' dis…
4568 </li>
4569
4570 <li>
4571 <p>the fourth step is the definition <a class='maruku-eqref' href='#eq:A…
4572 </li>
4573 </ul>
4574
4575 <p>These identifications show that <math class='maruku-mathml' display='…
4576
4577 <p>\end{proof}</p>
4578
4579 <p>\begin{example}\label{BZActionOnInertiaGroupoid} <strong>(<math class…
4580
4581 <ul>
4582 <li>
4583 <p><math class='maruku-mathml' display='inline' id='mathml_6bd24f22919d9…
4584
4585 <p>be a <a class='existingWikiWord' href='/nlab/show/discrete+group'>dis…
4586 </li>
4587
4588 <li>
4589 <p><math class='maruku-mathml' display='inline' id='mathml_6bd24f22919d9…
4590
4591 <p>be a <math class='maruku-mathml' display='inline' id='mathml_6bd24f22…
4592 </li>
4593
4594 <li>
4595 <p><math class='maruku-mathml' display='inline' id='mathml_6bd24f22919d9…
4596
4597 <p>the <a class='existingWikiWord' href='/nlab/show/simplicial+set'>simp…
4598 </li>
4599
4600 <li>
4601 <p><math class='maruku-mathml' display='inline' id='mathml_6bd24f22919d9…
4602
4603 <p>the <a class='existingWikiWord' href='/nlab/show/simplicial+group'>si…
4604 </li>
4605 </ul>
4606
4607 <p>Then the <a class='existingWikiWord' href='/nlab/show/functor+categor…
4608 <div class='maruku-equation' id='eq:InertiaGroupoidAsFunctorGroupoidOutO…
4609
4610 \begin{aligned}
4611 \Lambda(X \!\sslash\! G)
4612 &amp; \;\coloneqq\;
4613 \big[
4614 \mathbf{B}\mathbb{Z}, X \!\sslash\! G
4615 \big]
4616 \\
4617 &amp;
4618 \;\simeq\;
4619 Func
4620 \big(
4621 (\mathbb{Z} \rightrightarrows \ast),
4622 \,
4623 (X \times G \rightrightarrows X)
4624 \big)
4625 \\
4626 &amp; \;\underset{\in \mathrm{W}}{\leftarrow}\;
4627 \underset{
4628 [g] \in ConjCl(G)
4629 }{\coprod}
4630 \Big(
4631 X^{g} \!\sslash\! C_g
4632 \Big)
4633 \end{aligned}
4634
4635 </annotation></semantics></math></div>
4636 <p>is known as the <em><a class='existingWikiWord' href='/nlab/show/iner…
4637 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4638 ConjCla(G)
4639 \;\coloneqq\;
4640 G/_{ad} G
4641 \,,
4642 \;\;\;\;\;\;\;\;\;\;\;
4643 C_g
4644 \;\coloneqq\;
4645 \big\{
4646 h \in G
4647 \,\left\vert\,
4648 h \cdot g = g \cdot h
4649 \right.
4650 \big\}
4651
4652 </annotation></semantics></math></div>
4653 <p>denotes, respectively, the set of <a class='existingWikiWord' href='/…
4654
4655 <p>Now, by Prop. \ref{CofreeAction} the inertia groupoid <a class='maruk…
4656
4657 <p>By the formula <a class='maruku-eqref' href='#eq:CofreeSimplicialActi…
4658 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4659 {\color{purple}n}
4660 \;\colon\;
4661 \Delta[1]
4662 \longrightarrow
4663 \mathbf{B}G
4664
4665 </annotation></semantics></math></div>
4666 <p>acts on the morphisms</p>
4667 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4668 (x,g) \overset{h}{\longrightarrow} (h\cdot x, g)
4669 \;\;\;
4670 \in
4671 \;
4672 \Lambda(X \!\sslash\! G)
4673
4674 </annotation></semantics></math></div>
4675 <p>of the inertia groupoid as follows (recall the nature of <a class='ex…
4676
4677 <p><img src='https://ncatlab.org/nlab/files/BZActionOnInertiaGroupoid202…
4678
4679 <p>\end{example}</p>
4680
4681 <h3 id='relation_to_the_fine_model_structure_of_equivariant_homotopy_the…
4682
4683 <p>The <a class='existingWikiWord' href='/nlab/show/identity+functor'>id…
4684
4685 <p>The left adjoint is</p>
4686 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4687 L = id
4688 \;\colon\;
4689 G_\bullet Act_{coarse}
4690 \longrightarrow
4691 G_\bullet Act_{fine}
4692
4693 </annotation></semantics></math></div>
4694 <p>from the Borel model structure to the genuine <a class='existingWikiW…
4695
4696 <p>Because:</p>
4697
4698 <p>First of all, by (<a href='#Guillou'>Guillou, theorem 3.12, example 4…
4699 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4700 R = id \;\colon\; G_\bullet Act_{fine} \longrightarrow G_\bullet Act_{…
4701
4702 </annotation></semantics></math></div>
4703 <p>is right Quillen.</p>
4704
4705 <h3 id='GeneralizationToSimplicialPresheaves'>Generalization to simplici…
4706
4707 <p>Since the <a class='existingWikiWord' href='/nlab/show/simplicial+cla…
4708 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4709 SimplicialGroups
4710 \xrightarrow{\;\; W \;\;}
4711 SimplicialSets
4712
4713 </annotation></semantics></math></div>
4714 <p>with <a class='existingWikiWord' href='/nlab/show/natural+transformat…
4715 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4716 \mathcal{G}
4717 \xrightarrow{\;\; i \;\;}
4718 W\mathcal{G}
4719 \xrightarrow{\;\; p \;\;}
4720 \overline{W}\mathcal{G}
4721
4722 </annotation></semantics></math></div>
4723 <p>the pair of <a class='existingWikiWord' href='/nlab/show/adjoint+func…
4724
4725 <p>\begin{prop} For <math class='maruku-mathml' display='inline' id='mat…
4726 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4727 sPSh(\mathcal{C})
4728 \;\coloneqq\;
4729 sSetCat( \mathcal{C}^{op}, \, sSet )
4730
4731 </annotation></semantics></math></div>
4732 <p>denoting its category of <a class='existingWikiWord' href='/nlab/show…
4733 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4734 \underline{\mathcal{G}}
4735 \;\in\;
4736 Groups
4737 \big(
4738 sPSh(\mathcal{C})
4739 \big)
4740
4741 </annotation></semantics></math></div>
4742 <p>a <a class='existingWikiWord' href='/nlab/show/group+object'>group ob…
4743 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4744 \underline{\mathcal{G}}
4745 Acts
4746 \big(
4747 sPSh(\mathcal{C})
4748 \big)
4749
4750 </annotation></semantics></math></div>
4751 <p>denoting its category of <a class='existingWikiWord' href='/nlab/show…
4752
4753 <p>we have an <a class='existingWikiWord' href='/nlab/show/adjoint+funct…
4754 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4755 \underline{\mathcal{G}}
4756 Acts
4757 \big(
4758 sPSh(\mathcal{C})
4759 \big)
4760 \underoverset
4761 {
4762 \underset{
4763 \big(
4764 (-) \times W\underline{\mathcal{G}}
4765 \big)
4766 \big/
4767 \underline{\mathcal{G}}
4768 }
4769 {\longrightarrow}}
4770 {
4771 \overset{
4772 (-)
4773 \times_{\overline{W}\underline{\mathcal{G}}}
4774 W\underline{\mathcal{G}}
4775 }{\longleftarrow}
4776 }
4777 {\bot}
4778 sPSh(\mathcal{C})_{/\overline{W}\underline{\mathcal{G}}}
4779
4780 </annotation></semantics></math></div>
4781 <p>\end{prop} \begin{proof}</p>
4782
4783 <p>The required <a href='adjoint+functor#InTermsOfHomIsomorphism'>hom-is…
4784 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4785 \begin{aligned}
4786 Hom
4787 \Big(
4788 (\underline{X},p),
4789 \,
4790 \big(
4791 \underline{Y} \times W\underline{\mathcal{G}}
4792 \big) / \underline{\mathcal{G}}
4793 \Big)
4794 &amp;
4795 \;\simeq\;
4796 Hom
4797 \Big(
4798 \underline{X},
4799 \,
4800 \big(
4801 \underline{Y} \times W\underline{\mathcal{G}}
4802 \big) / \underline{\mathcal{G}}
4803 \Big)
4804 \underset{
4805 Hom
4806 \Big(
4807 \underline{X},
4808 \,
4809 \overline{W} \underline{\mathcal{G}}
4810 \Big)
4811 }{\times}
4812 \{p\}
4813 \\
4814 &amp; \;\simeq\;
4815 \int^c
4816 Hom
4817 \Big(
4818 \underline{X}(c),
4819 \,
4820 \big(
4821 \underline{Y}(c) \times W\underline{\mathcal{G}(c)}
4822 \big) / \underline{\mathcal{G}}(c)
4823 \Big)
4824 \underset{
4825 \int^c
4826 Hom
4827 \Big(
4828 \underline{X}(c),
4829 \,
4830 \overline{W} \underline{\mathcal{G}}(c)
4831 \Big)
4832 }{\times}
4833 \{p\}
4834 \\
4835 &amp; \;\simeq\;
4836 \int^c
4837 \left(
4838 Hom
4839 \Big(
4840 \underline{X}(c),
4841 \,
4842 \big(
4843 \underline{Y}(c) \times W\underline{\mathcal{G}}(c)
4844 \big) / \underline{\mathcal{G}}(c)
4845 \Big)
4846 \underset{
4847 Hom
4848 \Big(
4849 \underline{X}(c),
4850 \,
4851 \overline{W} \underline{\mathcal{G}}(c)
4852 \Big)
4853 }{\times}
4854 \{p(c)\}
4855 \right)
4856 \\
4857 &amp; \;\simeq\;
4858 \int^c
4859 Hom_{/\overline{W}\underline{\mathcal{G}}(c)}
4860 \Big(
4861 \big( \underline{X}(c), p(c)\big),
4862 \,
4863 \big(
4864 \underline{Y}(c) \times \overline{W} \underline{\mathcal{G}}(c)
4865 \big)\big/ \mathcal{G}(c)
4866 \Big)
4867 \\
4868 &amp; \;\simeq\;
4869 \int^c
4870 \left(
4871 \underline{\mathcal{G}}(c)
4872 Acts(sSet)
4873 \big(
4874 \underline{X}(c)
4875 \underset{ \overline{W}\underline{\mathcal{G}}(c) }{\times}
4876 W \underline{\mathcal{G}}(c),
4877 \,
4878 \underline{Y}(c)
4879 \big)
4880 \right)
4881 \\
4882 &amp; \;\simeq\;
4883 \mathcal{G}Acts(sPSh(\mathcal{C}))
4884 \big(
4885 \underline{X}
4886 \underset{\overline{W}\underline{\mathcal{G}}}{\times}
4887 W \underline{\mathcal{G}},
4888 \,
4889 \underline{Y}
4890 \big)
4891 \end{aligned}
4892
4893 </annotation></semantics></math></div>
4894 <p>Here:</p>
4895
4896 <ul>
4897 <li>
4898 <p>the first step is the characterization of hom-sets of a <a class='exi…
4899 </li>
4900
4901 <li>
4902 <p>the second step is the description of the hom-set of a <a class='exis…
4903 </li>
4904
4905 <li>
4906 <p>the third step uses that <a class='existingWikiWord' href='/nlab/show…
4907 </li>
4908
4909 <li>
4910 <p>the fourth step recognizes again, now object-wise, the hom-set in a <…
4911 </li>
4912
4913 <li>
4914 <p>the fifth step is objectwise the <a href='adjoint+functor#InTermsOfHo…
4915 </li>
4916
4917 <li>
4918 <p>the sixth step recognizes again the <a class='existingWikiWord' href=…
4919 </li>
4920 </ul>
4921 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
4922 \array{
4923 \underline{\mathcal{G}}Acts
4924 \big(
4925 \underline{A}, \, \underline{B}
4926 \big)
4927 &amp;\longrightarrow&amp;
4928 \mathcal{G}(c_1)Acts
4929 \big(
4930 \underline{A}(c_1), \, \underline{B}(c_1)
4931 \big)
4932 \\
4933 \big\downarrow
4934 &amp;&amp;
4935 \big\downarrow
4936 \\
4937 \mathcal{G}(c_2)Acts
4938 \big(
4939 \underline{A}(c_2), \, \underline{B}(c_2)
4940 \big)
4941 &amp;\longrightarrow&amp;
4942 Hom
4943 \big(
4944 \underline{A}(c_1), \, \underline{B}(c_2)
4945 \big)
4946 }
4947
4948 </annotation></semantics></math></div>
4949 <p>\end{proof}</p>
4950
4951 <h2 id='references'>References</h2>
4952
4953 <p>The model structure, the characterization of its cofibrations, and it…
4954
4955 <ul>
4956 <li id='DDK80'><a class='existingWikiWord' href='/nlab/show/Emmanuel+Dro…
4957 </ul>
4958
4959 <p>This Quillen equivalence also mentioned as:</p>
4960
4961 <ul>
4962 <li id='Dwyer2008'><a class='existingWikiWord' href='/nlab/show/William+…
4963 </ul>
4964
4965 <p>Discussion in relation to the “fine” model structure of <a class=…
4966
4967 <ul>
4968 <li id='Guillou'><a class='existingWikiWord' href='/nlab/show/Bert+Guill…
4969 </ul>
4970
4971 <p>Textbook account of (just) the Borel model structure:</p>
4972
4973 <ul>
4974 <li id='GoerssJardine09'><a class='existingWikiWord' href='/nlab/show/Pa…
4975 </ul>
4976
4977 <p>Discussion with the model of <a class='existingWikiWord' href='/nlab/…
4978
4979 <ul>
4980 <li><a class='existingWikiWord' href='/nlab/show/Matan+Prasma'>Matan Pra…
4981 </ul>
4982
4983 <p>Discussion of a <a class='existingWikiWord' href='/nlab/show/global+e…
4984
4985 <ul>
4986 <li><a class='existingWikiWord' href='/nlab/show/Yonatan+Harpaz'>Yonatan…
4987 </ul>
4988
4989 <p>
4990 </p> </div>
4991 </content>
4992 </entry>
4993 <entry>
4994 <title type="html">Sandbox</title>
4995 <link rel="alternate" type="application/xhtml+xml" href="https://nca…
4996 <updated>2021-07-01T16:14:56Z</updated>
4997 <published>2009-07-07T06:11:26Z</published>
4998 <id>tag:ncatlab.org,2009-07-07:nLab,Sandbox</id>
4999 <author>
5000 <name>Urs Schreiber</name>
5001 </author>
5002 <content type="xhtml" xml:base="https://ncatlab.org/nlab/show/Sandbo…
5003 <div xmlns="http://www.w3.org/1999/xhtml">
5004 <h3 id='GeneralizationToSimplicialPresheaves'>Generalization to simplici…
5005
5006 <p>Since the <a class='existingWikiWord' href='/nlab/show/simplicial+cla…
5007 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
5008 SimplicialGroups
5009 \xrightarrow{\;\; W \;\;}
5010 SimplicialSets
5011
5012 </annotation></semantics></math></div>
5013 <p>with <a class='existingWikiWord' href='/nlab/show/natural+transformat…
5014 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
5015 \mathcal{G}
5016 \xrightarrow{\;\; i \;\;}
5017 W\mathcal{G}
5018 \xrightarrow{\;\; p \;\;}
5019 \overline{W}\mathcal{G}
5020
5021 </annotation></semantics></math></div>
5022 <p>the pair of <a class='existingWikiWord' href='/nlab/show/adjoint+func…
5023
5024 <p>\begin{prop} For <math class='maruku-mathml' display='inline' id='mat…
5025 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
5026 sPSh(\mathcal{C})
5027 \;\coloneqq\;
5028 sSetCat( \mathcal{C}^{op}, \, sSet )
5029
5030 </annotation></semantics></math></div>
5031 <p>denoting its category of <a class='existingWikiWord' href='/nlab/show…
5032 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
5033 \underline{\mathcal{G}}
5034 \;\in\;
5035 Groups
5036 \big(
5037 sPSh(\mathcal{C})
5038 \big)
5039
5040 </annotation></semantics></math></div>
5041 <p>a <a class='existingWikiWord' href='/nlab/show/group+object'>group ob…
5042 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
5043 \underline{\mathcal{G}}
5044 Acts
5045 \big(
5046 sPSh(\mathcal{C})
5047 \big)
5048
5049 </annotation></semantics></math></div>
5050 <p>denoting its category of <a class='existingWikiWord' href='/nlab/show…
5051
5052 <p>we have an <a class='existingWikiWord' href='/nlab/show/adjoint+funct…
5053 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
5054 \underline{\mathcal{G}}
5055 Acts
5056 \big(
5057 sPSh(\mathcal{C})
5058 \big)
5059 \underoverset
5060 {
5061 \underset{
5062 \big(
5063 (-) \times W\underline{\mathcal{G}}
5064 \big)
5065 \big/
5066 \underline{\mathcal{G}}
5067 }
5068 {\longrightarrow}}
5069 {
5070 \overset{
5071 (-)
5072 \times_{\overline{W}\underline{\mathcal{G}}}
5073 W\underline{\mathcal{G}}
5074 }{\longleftarrow}
5075 }
5076 {\bot}
5077 sPSh(\mathcal{C})_{/\overline{W}\underline{\mathcal{G}}}
5078
5079 </annotation></semantics></math></div>
5080 <p>\end{prop} \begin{proof}</p>
5081
5082 <p>The required <a href='adjoint+functor#InTermsOfHomIsomorphism'>hom-is…
5083 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
5084 \begin{aligned}
5085 Hom
5086 \Big(
5087 (\underline{X},p),
5088 \,
5089 \big(
5090 \underline{Y} \times W\underline{\mathcal{G}}
5091 \big) / \underline{\mathcal{G}}
5092 \Big)
5093 &amp;
5094 \;\simeq\;
5095 Hom
5096 \Big(
5097 \underline{X},
5098 \,
5099 \big(
5100 \underline{Y} \times W\underline{\mathcal{G}}
5101 \big) / \underline{\mathcal{G}}
5102 \Big)
5103 \underset{
5104 Hom
5105 \Big(
5106 \underline{X},
5107 \,
5108 \overline{W} \underline{\mathcal{G}}
5109 \Big)
5110 }{\times}
5111 \{p\}
5112 \\
5113 &amp; \;\simeq\;
5114 \int^c
5115 Hom
5116 \Big(
5117 \underline{X}(c),
5118 \,
5119 \big(
5120 \underline{Y}(c) \times W\underline{\mathcal{G}(c)}
5121 \big) / \underline{\mathcal{G}}(c)
5122 \Big)
5123 \underset{
5124 \int^c
5125 Hom
5126 \Big(
5127 \underline{X}(c),
5128 \,
5129 \overline{W} \underline{\mathcal{G}}(c)
5130 \Big)
5131 }{\times}
5132 \{p\}
5133 \\
5134 &amp; \;\simeq\;
5135 \int^c
5136 \left(
5137 Hom
5138 \Big(
5139 \underline{X}(c),
5140 \,
5141 \big(
5142 \underline{Y}(c) \times W\underline{\mathcal{G}(c)}
5143 \big) / \underline{\mathcal{G}}(c)
5144 \Big)
5145 \underset{
5146 Hom
5147 \Big(
5148 \underline{X}(c),
5149 \,
5150 \overline{W} \underline{\mathcal{G}}(c)
5151 \Big)
5152 }{\times}
5153 \{p(c)\}
5154 \right)
5155 \\
5156 &amp; \;\simeq\;
5157 \int^c
5158 Hom_{/\overline{W}\underline{\mathcal{G}}(c)}
5159 \Big(
5160 \big(X(c), p(c)\big),
5161 \,
5162 \big(
5163 Y(c) \times \overline{W} \mathcal{G}(c)
5164 \big)\big/ \mathcal{G}(c)
5165 \Big)
5166 \\
5167 &amp; \;\simeq\;
5168 \int^c
5169 \left(
5170 \underline{\mathcal{G}}(c)
5171 Acts(sSet)
5172 \big(
5173 X(c)
5174 \underset{ \overline{W}\underline{\mathcal{G}}(c) }{\times}
5175 W \underline{\mathcal{G}}(c),
5176 \,
5177 Y(c)
5178 \big)
5179 \right)
5180 \\
5181 &amp; \;\simeq\;
5182 \mathcal{G}Acts(sPSh(\mathcal{C}))
5183 \big(
5184 X
5185 \underset{\overline{W}\underline{\mathcal{G}}}{\times}
5186 W \underline{\mathcal{G}},
5187 \,
5188 Y
5189 \big)
5190 \end{aligned}
5191
5192 </annotation></semantics></math></div>
5193 <p>Here:</p>
5194
5195 <ul>
5196 <li>
5197 <p>the first step is the characterization of hom-sets of a <a class='exi…
5198 </li>
5199
5200 <li>
5201 <p>the second step is the description of the hom-set of a <a class='exis…
5202 </li>
5203
5204 <li>
5205 <p>the third step uses that <a class='existingWikiWord' href='/nlab/show…
5206 </li>
5207
5208 <li>
5209 <p>the fourth step recognizes again, now object-wise, the hom-set in a <…
5210 </li>
5211
5212 <li>
5213 <p>the fifth step is objectwise the <a href='adjoint+functor#InTermsOfHo…
5214 </li>
5215
5216 <li>
5217 <p>the sixth step recognizes again the <a class='existingWikiWord' href=…
5218 </li>
5219 </ul>
5220 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
5221 \array{
5222 \underline{\mathcal{G}}Acts
5223 \big(
5224 A, \, B
5225 \big)
5226 &amp;\longrightarrow&amp;
5227 \mathcal{G}(c_1)Acts
5228 \big(
5229 A(c_1), \, B(c_1)
5230 \big)
5231 \\
5232 \big\downarrow
5233 &amp;&amp;
5234 \big\downarrow
5235 \\
5236 \mathcal{G}(c_2)Acts
5237 \big(
5238 A(c_2), \, B(c_2)
5239 \big)
5240 &amp;\longrightarrow&amp;
5241 Hom
5242 \big(
5243 A(c_1), \, B(c_2)
5244 \big)
5245 }
5246
5247 </annotation></semantics></math></div>
5248 <p>\end{proof}</p>
5249
5250 <p>\linebreak</p>
5251
5252 <p>\linebreak</p>
5253
5254 <p>added the observation (<a href='https://ncatlab.org/nlab/show/Borel+m…
5255 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
5256 \mathcal{G} Acts(sSet)
5257 \underoverset
5258 {\underset{ \big((-) \times W \mathcal{G}\big)/\mathcal{G} }{\lo…
5259 {\overset{ (-) \times_{\overline{W}\mathcal{G}} W \mathcal{G} }…
5260 {\bot}
5261 sSet_{/\overline{W}\mathcal{G}}
5262
5263 </annotation></semantics></math></div>
5264 <p>generalizes to one for presheaves of simplicial groups</p>
5265 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
5266 \underline{\mathcal{G}}
5267 Acts
5268 \big(
5269 sPSh(\mathcal{C})
5270 \big)
5271 \underoverset
5272 {
5273 \underset{
5274 \big(
5275 (-) \times W\underline{\mathcal{G}}
5276 \big)
5277 \big/
5278 \underline{\mathcal{G}}
5279 }
5280 {\longrightarrow}}
5281 {
5282 \overset{
5283 (-)
5284 \times_{\overline{W}\underline{\mathcal{G}}}
5285 W\underline{\mathcal{G}}
5286 }{\longleftarrow}
5287 }
5288 {\bot}
5289 sPSh(\mathcal{C})_{/\overline{W}\underline{\mathcal{G}}}
5290
5291 </annotation></semantics></math></div> </div>
5292 </content>
5293 </entry>
5294 <entry>
5295 <title type="html">simplicial presheaf</title>
5296 <link rel="alternate" type="application/xhtml+xml" href="https://nca…
5297 <updated>2021-07-01T14:31:25Z</updated>
5298 <published>2009-01-29T18:34:04Z</published>
5299 <id>tag:ncatlab.org,2009-01-29:nLab,simplicial+presheaf</id>
5300 <author>
5301 <name>Urs Schreiber</name>
5302 </author>
5303 <content type="xhtml" xml:base="https://ncatlab.org/nlab/show/simpli…
5304 <div xmlns="http://www.w3.org/1999/xhtml">
5305 <div class='rightHandSide'>
5306 <div class='toc clickDown' tabindex='0'>
5307 <h3 id='context'>Context</h3>
5308
5309 <h4 id='homotopy_theory'>Homotopy theory</h4>
5310
5311 <div class='hide'>
5312 <p><strong><a class='existingWikiWord' href='/nlab/show/homotopy+theory'…
5313
5314 <p>flavors: <a class='existingWikiWord' href='/nlab/show/stable+homotopy…
5315
5316 <p>models: <a class='existingWikiWord' href='/nlab/show/topological+homo…
5317
5318 <p>see also <strong><a class='existingWikiWord' href='/nlab/show/algebra…
5319
5320 <p><strong>Introductions</strong></p>
5321
5322 <ul>
5323 <li>
5324 <p><a class='existingWikiWord' href='/nlab/show/Introduction+to+Topology…
5325 </li>
5326
5327 <li>
5328 <p><a class='existingWikiWord' href='/nlab/show/Introduction+to+Homotopy…
5329 </li>
5330
5331 <li>
5332 <p><a class='existingWikiWord' href='/nlab/show/geometry+of+physics+--+h…
5333 </li>
5334 </ul>
5335
5336 <p><strong>Definitions</strong></p>
5337
5338 <ul>
5339 <li>
5340 <p><a class='existingWikiWord' href='/nlab/show/homotopy'>homotopy</a>, …
5341 </li>
5342
5343 <li>
5344 <p><a class='existingWikiWord' href='/nlab/show/homotopy+type'>homotopy …
5345 </li>
5346
5347 <li>
5348 <p><a class='existingWikiWord' href='/nlab/show/Pi-algebra'>Pi-algebra</…
5349 </li>
5350
5351 <li>
5352 <p><a class='existingWikiWord' href='/nlab/show/homotopy+coherent+catego…
5353
5354 <ul>
5355 <li>
5356 <p><a class='existingWikiWord' href='/nlab/show/homotopical+category'>ho…
5357
5358 <ul>
5359 <li>
5360 <p><a class='existingWikiWord' href='/nlab/show/model+category'>model ca…
5361 </li>
5362
5363 <li>
5364 <p><a class='existingWikiWord' href='/nlab/show/category+of+fibrant+obje…
5365 </li>
5366
5367 <li>
5368 <p><a class='existingWikiWord' href='/nlab/show/Waldhausen+category'>Wal…
5369 </li>
5370 </ul>
5371 </li>
5372
5373 <li>
5374 <p><a class='existingWikiWord' href='/nlab/show/homotopy+category'>homot…
5375
5376 <ul>
5377 <li><a class='existingWikiWord' href='/nlab/show/Ho%28Top%29'>Ho(Top)</a…
5378 </ul>
5379 </li>
5380 </ul>
5381 </li>
5382
5383 <li>
5384 <p><a class='existingWikiWord' href='/nlab/show/%28infinity%2C1%29-categ…
5385
5386 <ul>
5387 <li><a class='existingWikiWord' href='/nlab/show/homotopy+category+of+an…
5388 </ul>
5389 </li>
5390 </ul>
5391
5392 <p><strong>Paths and cylinders</strong></p>
5393
5394 <ul>
5395 <li>
5396 <p><a class='existingWikiWord' href='/nlab/show/homotopy'>left homotopy<…
5397
5398 <ul>
5399 <li>
5400 <p><a class='existingWikiWord' href='/nlab/show/cylinder+object'>cylinde…
5401 </li>
5402
5403 <li>
5404 <p><a class='existingWikiWord' href='/nlab/show/mapping+cone'>mapping co…
5405 </li>
5406 </ul>
5407 </li>
5408
5409 <li>
5410 <p><a class='existingWikiWord' href='/nlab/show/homotopy'>right homotopy…
5411
5412 <ul>
5413 <li>
5414 <p><a class='existingWikiWord' href='/nlab/show/path+space+object'>path …
5415 </li>
5416
5417 <li>
5418 <p><a class='existingWikiWord' href='/nlab/show/mapping+cocone'>mapping …
5419 </li>
5420
5421 <li>
5422 <p><a class='existingWikiWord' href='/nlab/show/generalized+universal+bu…
5423 </li>
5424 </ul>
5425 </li>
5426
5427 <li>
5428 <p><a class='existingWikiWord' href='/nlab/show/interval+object'>interva…
5429
5430 <ul>
5431 <li>
5432 <p><a class='existingWikiWord' href='/nlab/show/localization+at+geometri…
5433 </li>
5434
5435 <li>
5436 <p><a class='existingWikiWord' href='/nlab/show/infinitesimal+interval+o…
5437 </li>
5438 </ul>
5439 </li>
5440 </ul>
5441
5442 <p><strong>Homotopy groups</strong></p>
5443
5444 <ul>
5445 <li>
5446 <p><a class='existingWikiWord' href='/nlab/show/homotopy+group'>homotopy…
5447
5448 <ul>
5449 <li>
5450 <p><a class='existingWikiWord' href='/nlab/show/fundamental+group'>funda…
5451
5452 <ul>
5453 <li><a class='existingWikiWord' href='/nlab/show/fundamental+group+of+a+…
5454 </ul>
5455 </li>
5456
5457 <li>
5458 <p><a class='existingWikiWord' href='/nlab/show/Brown-Grossman+homotopy+…
5459 </li>
5460
5461 <li>
5462 <p><a class='existingWikiWord' href='/nlab/show/categorical+homotopy+gro…
5463 </li>
5464
5465 <li>
5466 <p><a class='existingWikiWord' href='/nlab/show/geometric+homotopy+group…
5467 </li>
5468 </ul>
5469 </li>
5470
5471 <li>
5472 <p><a class='existingWikiWord' href='/nlab/show/fundamental+infinity-gro…
5473
5474 <ul>
5475 <li>
5476 <p><a class='existingWikiWord' href='/nlab/show/fundamental+groupoid'>fu…
5477
5478 <ul>
5479 <li><a class='existingWikiWord' href='/nlab/show/path+groupoid'>path gro…
5480 </ul>
5481 </li>
5482
5483 <li>
5484 <p><a class='existingWikiWord' href='/nlab/show/fundamental+infinity-gro…
5485 </li>
5486
5487 <li>
5488 <p><a class='existingWikiWord' href='/nlab/show/fundamental+infinity-gro…
5489 </li>
5490 </ul>
5491 </li>
5492
5493 <li>
5494 <p><a class='existingWikiWord' href='/nlab/show/fundamental+%28infinity%…
5495
5496 <ul>
5497 <li><a class='existingWikiWord' href='/nlab/show/fundamental+category'>f…
5498 </ul>
5499 </li>
5500 </ul>
5501
5502 <p><strong>Basic facts</strong></p>
5503
5504 <ul>
5505 <li><a class='existingWikiWord' href='/nlab/show/fundamental+group+of+th…
5506 </ul>
5507
5508 <p><strong>Theorems</strong></p>
5509
5510 <ul>
5511 <li>
5512 <p><a class='existingWikiWord' href='/nlab/show/fundamental+theorem+of+c…
5513 </li>
5514
5515 <li>
5516 <p><a class='existingWikiWord' href='/nlab/show/Freudenthal+suspension+t…
5517 </li>
5518
5519 <li>
5520 <p><a class='existingWikiWord' href='/nlab/show/Blakers-Massey+theorem'>…
5521 </li>
5522
5523 <li>
5524 <p><a class='existingWikiWord' href='/nlab/show/higher+homotopy+van+Kamp…
5525 </li>
5526
5527 <li>
5528 <p><a class='existingWikiWord' href='/nlab/show/nerve+theorem'>nerve the…
5529 </li>
5530
5531 <li>
5532 <p><a class='existingWikiWord' href='/nlab/show/Whitehead+theorem'>White…
5533 </li>
5534
5535 <li>
5536 <p><a class='existingWikiWord' href='/nlab/show/Hurewicz+theorem'>Hurewi…
5537 </li>
5538
5539 <li>
5540 <p><a class='existingWikiWord' href='/nlab/show/Galois+theory'>Galois th…
5541 </li>
5542
5543 <li>
5544 <p><a class='existingWikiWord' href='/nlab/show/homotopy+hypothesis'>hom…
5545 </li>
5546 </ul>
5547 </div>
5548
5549 <h4 id='topos_theory'><math class='maruku-mathml' display='inline' id='m…
5550
5551 <div class='hide'>
5552 <p><strong><a class='existingWikiWord' href='/nlab/show/%28infinity%2C1%…
5553
5554 <h2 id='background'>Background</h2>
5555
5556 <ul>
5557 <li>
5558 <p><a class='existingWikiWord' href='/nlab/show/sheaf+and+topos+theory'>…
5559 </li>
5560
5561 <li>
5562 <p><a class='existingWikiWord' href='/nlab/show/%28infinity%2C1%29-categ…
5563 </li>
5564
5565 <li>
5566 <p><a class='existingWikiWord' href='/nlab/show/%28infinity%2C1%29-funct…
5567 </li>
5568
5569 <li>
5570 <p><a class='existingWikiWord' href='/nlab/show/%28infinity%2C1%29-presh…
5571 </li>
5572
5573 <li>
5574 <p><a class='existingWikiWord' href='/nlab/show/%28infinity%2C1%29-categ…
5575 </li>
5576 </ul>
5577
5578 <h2 id='definitions'>Definitions</h2>
5579
5580 <ul>
5581 <li>
5582 <p><a class='existingWikiWord' href='/nlab/show/elementary+%28infinity%2…
5583 </li>
5584
5585 <li>
5586 <p><a class='existingWikiWord' href='/nlab/show/%28infinity%2C1%29-site'…
5587 </li>
5588
5589 <li>
5590 <p><a class='existingWikiWord' href='/nlab/show/reflective+sub-%28infini…
5591
5592 <ul>
5593 <li>
5594 <p><a class='existingWikiWord' href='/nlab/show/localization+of+an+%28in…
5595 </li>
5596
5597 <li>
5598 <p><a class='existingWikiWord' href='/nlab/show/topological+localization…
5599 </li>
5600
5601 <li>
5602 <p><a class='existingWikiWord' href='/nlab/show/hypercompletion'>hyperco…
5603 </li>
5604 </ul>
5605 </li>
5606
5607 <li>
5608 <p><a class='existingWikiWord' href='/nlab/show/%28infinity%2C1%29-categ…
5609
5610 <ul>
5611 <li><a class='existingWikiWord' href='/nlab/show/%28infinity%2C1%29-shea…
5612 </ul>
5613 </li>
5614
5615 <li>
5616 <p><a class='existingWikiWord' href='/nlab/show/%28infinity%2C1%29-topos…
5617 </li>
5618
5619 <li>
5620 <p><a class='existingWikiWord' href='/nlab/show/%28n%2C1%29-topos'>(n,1)…
5621
5622 <ul>
5623 <li>
5624 <p><a class='existingWikiWord' href='/nlab/show/truncated+object'>n-trun…
5625 </li>
5626
5627 <li>
5628 <p><a class='existingWikiWord' href='/nlab/show/connected+object'>n-conn…
5629 </li>
5630
5631 <li>
5632 <p><a class='existingWikiWord' href='/nlab/show/topos'>(1,1)-topos</a></…
5633
5634 <ul>
5635 <li>
5636 <p><a class='existingWikiWord' href='/nlab/show/presheaf'>presheaf</a></…
5637 </li>
5638
5639 <li>
5640 <p><a class='existingWikiWord' href='/nlab/show/sheaf'>sheaf</a></p>
5641 </li>
5642 </ul>
5643 </li>
5644
5645 <li>
5646 <p><a class='existingWikiWord' href='/nlab/show/2-topos'>(2,1)-topos</a>…
5647
5648 <ul>
5649 <li><a class='existingWikiWord' href='/nlab/show/%282%2C1%29-presheaf'>(…
5650 </ul>
5651 </li>
5652 </ul>
5653 </li>
5654
5655 <li>
5656 <p><a class='existingWikiWord' href='/nlab/show/%28infinity%2C1%29-quasi…
5657
5658 <ul>
5659 <li>
5660 <p><a class='existingWikiWord' href='/nlab/show/separated+%28infinity%2C…
5661 </li>
5662
5663 <li>
5664 <p><a class='existingWikiWord' href='/nlab/show/quasitopos'>quasitopos</…
5665
5666 <ul>
5667 <li><a class='existingWikiWord' href='/nlab/show/separated+presheaf'>sep…
5668 </ul>
5669 </li>
5670
5671 <li>
5672 <p><span class='newWikiWord'>(2,1)-quasitopos<a href='/nlab/new/%282%2C1…
5673
5674 <ul>
5675 <li><a class='existingWikiWord' href='/nlab/show/separated+%282%2C1%29-p…
5676 </ul>
5677 </li>
5678 </ul>
5679 </li>
5680
5681 <li>
5682 <p><a class='existingWikiWord' href='/nlab/show/%28infinity%2C2%29-topos…
5683 </li>
5684
5685 <li>
5686 <p><a class='existingWikiWord' href='/nlab/show/%28infinity%2Cn%29-topos…
5687 </li>
5688 </ul>
5689
5690 <h2 id='characterization'>Characterization</h2>
5691
5692 <ul>
5693 <li>
5694 <p><a class='existingWikiWord' href='/nlab/show/pullback-stable+colimit'…
5695 </li>
5696
5697 <li>
5698 <p><a class='existingWikiWord' href='/nlab/show/%28sub%29object+classifi…
5699 </li>
5700
5701 <li>
5702 <p><a class='existingWikiWord' href='/nlab/show/groupoid+object+in+an+%2…
5703
5704 <ul>
5705 <li><a class='existingWikiWord' href='/nlab/show/effective+epimorphism'>…
5706 </ul>
5707 </li>
5708 </ul>
5709
5710 <h2 id='morphisms'>Morphisms</h2>
5711
5712 <ul>
5713 <li>
5714 <p><a class='existingWikiWord' href='/nlab/show/%28infinity%2C1%29-geome…
5715 </li>
5716
5717 <li>
5718 <p><a class='existingWikiWord' href='/nlab/show/%28infinity%2C1%29Topos'…
5719 </li>
5720
5721 <li>
5722 <p><a class='existingWikiWord' href='/nlab/show/Lawvere+distribution'>La…
5723 </li>
5724 </ul>
5725
5726 <h2 id='extra_stuff_structure_and_property'>Extra stuff, structure and p…
5727
5728 <ul>
5729 <li>
5730 <p><a class='existingWikiWord' href='/nlab/show/hypercomplete+%28infinit…
5731
5732 <ul>
5733 <li>
5734 <p><a class='existingWikiWord' href='/nlab/show/hypercomplete+object'>hy…
5735 </li>
5736
5737 <li>
5738 <p><a class='existingWikiWord' href='/nlab/show/Whitehead+theorem'>White…
5739 </li>
5740 </ul>
5741 </li>
5742
5743 <li>
5744 <p><a class='existingWikiWord' href='/nlab/show/over-%28infinity%2C1%29-…
5745 </li>
5746
5747 <li>
5748 <p><a class='existingWikiWord' href='/nlab/show/n-localic+%28infinity%2C…
5749 </li>
5750
5751 <li>
5752 <p><a class='existingWikiWord' href='/nlab/show/locally+n-connected+%28n…
5753 </li>
5754
5755 <li>
5756 <p><a class='existingWikiWord' href='/nlab/show/structured+%28infinity%2…
5757
5758 <ul>
5759 <li><a class='existingWikiWord' href='/nlab/show/geometry+%28for+structu…
5760 </ul>
5761 </li>
5762
5763 <li>
5764 <p><a class='existingWikiWord' href='/nlab/show/locally+n-connected+%28n…
5765 </li>
5766
5767 <li>
5768 <p><a class='existingWikiWord' href='/nlab/show/%28%E2%88%9E%2C1%29-loca…
5769
5770 <ul>
5771 <li><a class='existingWikiWord' href='/nlab/show/concrete+%28infinity%2C…
5772 </ul>
5773 </li>
5774
5775 <li>
5776 <p><a class='existingWikiWord' href='/nlab/show/cohesive+%28infinity%2C1…
5777 </li>
5778 </ul>
5779
5780 <h2 id='models'>Models</h2>
5781
5782 <ul>
5783 <li>
5784 <p><a class='existingWikiWord' href='/nlab/show/presentations+of+%28infi…
5785
5786 <ul>
5787 <li>
5788 <p><a class='existingWikiWord' href='/nlab/show/model+category'>model ca…
5789 </li>
5790
5791 <li>
5792 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+funct…
5793 </li>
5794
5795 <li>
5796 <p><a class='existingWikiWord' href='/nlab/show/model+site'>model site</…
5797 </li>
5798
5799 <li>
5800 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+simpl…
5801 </li>
5802
5803 <li>
5804 <p><a class='existingWikiWord' href='/nlab/show/descent+for+simplicial+p…
5805 </li>
5806
5807 <li>
5808 <p><a class='existingWikiWord' href='/nlab/show/Verity+on+descent+for+st…
5809 </li>
5810 </ul>
5811 </li>
5812 </ul>
5813
5814 <h2 id='constructions'>Constructions</h2>
5815
5816 <p><strong>structures in a <a class='existingWikiWord' href='/nlab/show/…
5817
5818 <ul>
5819 <li>
5820 <p><a class='existingWikiWord' href='/nlab/show/shape+of+an+%28infinity%…
5821 </li>
5822
5823 <li>
5824 <p><a class='existingWikiWord' href='/nlab/show/cohomology'>cohomology</…
5825 </li>
5826
5827 <li>
5828 <p><a class='existingWikiWord' href='/nlab/show/homotopy+groups+in+an+%2…
5829
5830 <ul>
5831 <li>
5832 <p><a class='existingWikiWord' href='/nlab/show/fundamental+infinity-gro…
5833 </li>
5834
5835 <li>
5836 <p><a class='existingWikiWord' href='/nlab/show/categorical+homotopy+gro…
5837 </li>
5838
5839 <li>
5840 <p><a class='existingWikiWord' href='/nlab/show/Postnikov+tower+in+an+%2…
5841 </li>
5842
5843 <li>
5844 <p><a class='existingWikiWord' href='/nlab/show/Whitehead+tower+in+an+%2…
5845 </li>
5846 </ul>
5847 </li>
5848
5849 <li>
5850 <p><a class='existingWikiWord' href='/nlab/show/function+algebras+on+inf…
5851 </li>
5852
5853 <li>
5854 <p><a class='existingWikiWord' href='/nlab/show/dimension'>dimension</a>…
5855
5856 <ul>
5857 <li>
5858 <p><a class='existingWikiWord' href='/nlab/show/homotopy+dimension'>homo…
5859 </li>
5860
5861 <li>
5862 <p><a class='existingWikiWord' href='/nlab/show/cohomological+dimension'…
5863 </li>
5864
5865 <li>
5866 <p><a class='existingWikiWord' href='/nlab/show/covering+dimension'>cove…
5867 </li>
5868
5869 <li>
5870 <p><a class='existingWikiWord' href='/nlab/show/Heyting+dimension'>Heyti…
5871 </li>
5872 </ul>
5873 </li>
5874 </ul>
5875 <div>
5876 <p>
5877 <a href='/nlab/edit/%28infinity%2C1%29-topos+-+contents'>Edit this sid…
5878 </p>
5879 </div></div>
5880 </div>
5881 </div>
5882
5883 <h1 id='contents'>Contents</h1>
5884 <div class='maruku_toc'><ul><li><a href='#definition'>Definition</a></li…
5885 <h2 id='definition'>Definition</h2>
5886
5887 <p><em>Simplicial presheaves</em> over some <a class='existingWikiWord' …
5888
5889 <ul>
5890 <li><a class='existingWikiWord' href='/nlab/show/presheaf'>Presheaves</a…
5891 </ul>
5892
5893 <p>or equivalently, using the Hom-<a class='existingWikiWord' href='/nla…
5894
5895 <ul>
5896 <li>simplicial objects in the category of presheaves, i.e. functors <mat…
5897 </ul>
5898
5899 <h2 id='interpretation_as_stacks'>Interpretation as <math class='maruku-…
5900
5901 <p>Regarding <math class='maruku-mathml' display='inline' id='mathml_ebe…
5902
5903 <p>In more illustrative language this means that a simplicial presheaf o…
5904
5905 <h2 id='examples'>Examples</h2>
5906
5907 <ul>
5908 <li>
5909 <p>Notice that most definitions of <math class='maruku-mathml' display='…
5910 </li>
5911
5912 <li>
5913 <p>In particular, regarding a <a class='existingWikiWord' href='/nlab/sh…
5914 </li>
5915 </ul>
5916
5917 <h2 id='remarks'>Remarks</h2>
5918
5919 <ul>
5920 <li>There are various useful <a class='existingWikiWord' href='/nlab/sho…
5921 </ul>
5922
5923 <h2 id='properties'>Properties</h2>
5924
5925 <p>Here are some basic but useful facts about simplicial presheaves.</p>
5926
5927 <div class='un_prop'>
5928 <h6 id='proposition'>Proposition</h6>
5929
5930 <p>Every simplicial presheaf <math class='maruku-mathml' display='inline…
5931
5932 <p>More precisely, for <math class='maruku-mathml' display='inline' id='…
5933 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
5934 hocolim_{[n] \in \Delta} D_X([n]) \stackrel{\simeq}{\to} X
5935 \,.
5936
5937 </annotation></semantics></math></div></div>
5938
5939 <div class='proof'>
5940 <h6 id='proof'>Proof</h6>
5941
5942 <p>See for instance <a href='http://www.math.uiuc.edu/K-theory/0563/spre…
5943
5944 <ul>
5945 <li><a class='existingWikiWord' href='/nlab/show/Daniel+Dugger'>Daniel D…
5946 </ul>
5947
5948 <p>(which is otherwise about <a class='existingWikiWord' href='/nlab/sho…
5949 </div>
5950
5951 <div class='un_cor'>
5952 <h6 id='corollary'>Corollary</h6>
5953
5954 <p>Let <math class='maruku-mathml' display='inline' id='mathml_ebe0afceb…
5955
5956 <p>It follows in particular from the above that every such <a class='exi…
5957 </div>
5958
5959 <div class='proof'>
5960 <h6 id='proof_2'>Proof</h6>
5961
5962 <p>First the above yields</p>
5963 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
5964 \begin{aligned}
5965 [X, A ] &amp; \simeq [ hocolim_{[n] \in \Delta} X_n , A ]
5966 \\
5967 &amp; holim_{[n] \in \Delta} [X_n, A]
5968 \end{aligned}
5969 \,.
5970
5971 </annotation></semantics></math></div>
5972 <p>Next from the <a class='existingWikiWord' href='/nlab/show/co-Yoneda+…
5973 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
5974 \begin{aligned}
5975 \cdots &amp; \simeq
5976 holim_{[n] \in \Delta}
5977 [ colim_i U_{i}, A]
5978 \\
5979 &amp; \simeq
5980 holim_{[n] \in \Delta} lim_i
5981 [ U_{i}, A]
5982 \end{aligned}
5983 \,.
5984
5985 </annotation></semantics></math></div>
5986 <p>And finally the <a class='existingWikiWord' href='/nlab/show/Yoneda+l…
5987 <div class='maruku-equation'><math class='maruku-mathml' display='block'…
5988 \begin{aligned}
5989 \cdots
5990 &amp;
5991 holim_{[n] \in \Delta} lim_i
5992 A(U_i)
5993 \end{aligned}
5994 \,.
5995
5996 </annotation></semantics></math></div></div>
5997
5998 <p>Notice that these kinds of computations are in particular often used …
5999
6000 <h2 id='related_entries'>Related entries</h2>
6001
6002 <ul>
6003 <li>
6004 <p><a class='existingWikiWord' href='/nlab/show/model+structure+on+simpl…
6005 </li>
6006
6007 <li>
6008 <p><a class='existingWikiWord' href='/nlab/show/descent+for+simplicial+p…
6009 </li>
6010
6011 <li>
6012 <p><a class='existingWikiWord' href='/nlab/show/sheaf+of+spectra'>preshe…
6013 </li>
6014 </ul>
6015
6016 <p>Applications appear for instance at</p>
6017
6018 <ul>
6019 <li><a class='existingWikiWord' href='/nlab/show/geometric+infinity-func…
6020 </ul>
6021
6022 <h2 id='references'>References</h2>
6023
6024 <p>The original articles are</p>
6025
6026 <ul>
6027 <li>
6028 <p><a class='existingWikiWord' href='/nlab/show/Kenneth+Brown'>Kenneth S…
6029 </li>
6030
6031 <li>
6032 <p><a class='existingWikiWord' href='/nlab/show/Kenneth+Brown'>Kenneth S…
6033 </li>
6034
6035 <li>
6036 <p><a class='existingWikiWord' href='/nlab/show/John+Frederick+Jardine'>…
6037 </li>
6038
6039 <li>
6040 <p><a class='existingWikiWord' href='/nlab/show/John+Frederick+Jardine'>…
6041 </li>
6042 </ul>
6043
6044 <p>A modern expository account is</p>
6045
6046 <ul>
6047 <li><a class='existingWikiWord' href='/nlab/show/John+Frederick+Jardine'…
6048 </ul>
6049
6050 <p>Further articles:</p>
6051
6052 <ul>
6053 <li>
6054 <p><a class='existingWikiWord' href='/nlab/show/John+Frederick+Jardine'>…
6055 </li>
6056
6057 <li>
6058 <p><a class='existingWikiWord' href='/nlab/show/John+Frederick+Jardine'>…
6059 </li>
6060 </ul>
6061
6062 <p>For their interpretation in the more general context of <a class='exi…
6063
6064 <ul>
6065 <li><a class='existingWikiWord' href='/nlab/show/Jacob+Lurie'>Jacob Luri…
6066 </ul>
6067
6068 <p>
6069 </p>
6070
6071 <p>
6072
6073 </p>
6074
6075 <p>
6076 </p> </div>
6077 </content>
6078 </entry>
6079 <entry>
6080 <title type="html">Milky Way</title>
6081 <link rel="alternate" type="application/xhtml+xml" href="https://nca…
6082 <updated>2021-07-01T10:22:24Z</updated>
6083 <published>2019-04-10T13:55:53Z</published>
6084 <id>tag:ncatlab.org,2019-04-10:nLab,Milky+Way</id>
6085 <author>
6086 <name>Urs Schreiber</name>
6087 </author>
6088 <content type="xhtml" xml:base="https://ncatlab.org/nlab/show/Milky+…
6089 <div xmlns="http://www.w3.org/1999/xhtml">
6090 <div class='rightHandSide'>
6091 <div class='toc clickDown' tabindex='0'>
6092 <h3 id='context'>Context</h3>
6093
6094 <h4 id='physics'>Physics</h4>
6095
6096 <div class='hide'>
6097 <p><strong><a class='existingWikiWord' href='/nlab/show/physics'>physics…
6098
6099 <h2 id='surveys_textbooks_and_lecture_notes'>Surveys, textbooks and lect…
6100
6101 <ul>
6102 <li>
6103 <p><em><a class='existingWikiWord' href='/nlab/show/higher+category+theo…
6104 </li>
6105
6106 <li>
6107 <p><em><a class='existingWikiWord' href='/nlab/show/geometry+of+physics'…
6108 </li>
6109
6110 <li>
6111 <p><a class='existingWikiWord' href='/nlab/show/books+and+reviews+in+mat…
6112 </li>
6113 </ul>
6114 <hr/>
6115 <p><a class='existingWikiWord' href='/nlab/show/theory+%28physics%29'>th…
6116
6117 <p><a class='existingWikiWord' href='/nlab/show/experimental+observation…
6118
6119 <ul>
6120 <li>
6121 <p><strong><a class='existingWikiWord' href='/nlab/show/mechanics'>mecha…
6122
6123 <ul>
6124 <li>
6125 <p><a class='existingWikiWord' href='/nlab/show/mass'>mass</a>, <a class…
6126 </li>
6127
6128 <li>
6129 <p><a class='existingWikiWord' href='/nlab/show/Hamiltonian+dynamics+on+…
6130
6131 <ul>
6132 <li><a class='existingWikiWord' href='/nlab/show/rigid+body+dynamics'>ri…
6133 </ul>
6134 </li>
6135 </ul>
6136 </li>
6137
6138 <li>
6139 <p><a class='existingWikiWord' href='/nlab/show/field+%28physics%29'>fie…
6140
6141 <ul>
6142 <li>
6143 <p><a class='existingWikiWord' href='/nlab/show/Lagrangian+density'>Lagr…
6144
6145 <ul>
6146 <li>
6147 <p><a class='existingWikiWord' href='/nlab/show/configuration+space'>con…
6148 </li>
6149
6150 <li>
6151 <p><a class='existingWikiWord' href='/nlab/show/action+functional'>actio…
6152 </li>
6153
6154 <li>
6155 <p><a class='existingWikiWord' href='/nlab/show/phase+space'>covariant p…
6156 </li>
6157 </ul>
6158 </li>
6159
6160 <li>
6161 <p><a class='existingWikiWord' href='/nlab/show/Hamiltonian+mechanics'>H…
6162
6163 <ul>
6164 <li>
6165 <p><a class='existingWikiWord' href='/nlab/show/phase+space'>phase space…
6166 </li>
6167
6168 <li>
6169 <p><a class='existingWikiWord' href='/nlab/show/symplectic+geometry'>sym…
6170
6171 <ul>
6172 <li>
6173 <p><a class='existingWikiWord' href='/nlab/show/Poisson+manifold'>Poisso…
6174 </li>
6175
6176 <li>
6177 <p><a class='existingWikiWord' href='/nlab/show/symplectic+manifold'>sym…
6178 </li>
6179
6180 <li>
6181 <p><a class='existingWikiWord' href='/nlab/show/symplectic+groupoid'>sym…
6182 </li>
6183 </ul>
6184 </li>
6185
6186 <li>
6187 <p><a class='existingWikiWord' href='/nlab/show/multisymplectic+geometry…
6188
6189 <ul>
6190 <li><a class='existingWikiWord' href='/nlab/show/symplectic+Lie+n-algebr…
6191 </ul>
6192 </li>
6193 </ul>
6194 </li>
6195
6196 <li>
6197 <p><a class='existingWikiWord' href='/nlab/show/spacetime'>spacetime</a>…
6198
6199 <ul>
6200 <li>
6201 <p><a class='existingWikiWord' href='/nlab/show/smooth+Lorentzian+space'…
6202 </li>
6203
6204 <li>
6205 <p><a class='existingWikiWord' href='/nlab/show/special+relativity'>spec…
6206 </li>
6207
6208 <li>
6209 <p><a class='existingWikiWord' href='/nlab/show/general+relativity'>gene…
6210 </li>
6211
6212 <li>
6213 <p><a class='existingWikiWord' href='/nlab/show/gravity'>gravity</a></p>
6214
6215 <ul>
6216 <li>
6217 <p><a class='existingWikiWord' href='/nlab/show/supergravity'>supergravi…
6218 </li>
6219
6220 <li>
6221 <p><a class='existingWikiWord' href='/nlab/show/black+hole'>black hole</…
6222 </li>
6223 </ul>
6224 </li>
6225 </ul>
6226 </li>
6227 </ul>
6228 </li>
6229
6230 <li>
6231 <p><strong><a class='existingWikiWord' href='/nlab/show/classical+field+…
6232
6233 <ul>
6234 <li>
6235 <p><a class='existingWikiWord' href='/nlab/show/classical+physics'>class…
6236
6237 <ul>
6238 <li><a class='existingWikiWord' href='/nlab/show/classical+mechanics'>cl…
6239
6240 <li><a class='existingWikiWord' href='/nlab/show/wave'>waves</a> and <a …
6241
6242 <li><a class='existingWikiWord' href='/nlab/show/thermodynamics'>thermod…
6243 </ul>
6244 </li>
6245 </ul>
6246 </li>
6247
6248 <li>
6249 <p><strong><a class='existingWikiWord' href='/nlab/show/quantum+mechanic…
6250
6251 <ul>
6252 <li>
6253 <p><a class='existingWikiWord' href='/nlab/show/finite+quantum+mechanics…
6254 </li>
6255
6256 <li>
6257 <p><a class='existingWikiWord' href='/nlab/show/quantum+information'>qua…
6258 </li>
6259
6260 <li>
6261 <p><a class='existingWikiWord' href='/nlab/show/Hamiltonian'>Hamiltonian…
6262 </li>
6263
6264 <li>
6265 <p><a class='existingWikiWord' href='/nlab/show/density+matrix'>density …
6266 </li>
6267
6268 <li>
6269 <p><a class='existingWikiWord' href='/nlab/show/Kochen-Specker+theorem'>…
6270 </li>
6271
6272 <li>
6273 <p><a class='existingWikiWord' href='/nlab/show/Bell%27s+theorem'>Bell&#…
6274 </li>
6275
6276 <li>
6277 <p><a class='existingWikiWord' href='/nlab/show/Gleason%27s+theorem'>Gle…
6278 </li>
6279 </ul>
6280 </li>
6281
6282 <li>
6283 <p><strong><a class='existingWikiWord' href='/nlab/show/quantization'>Qu…
6284
6285 <ul>
6286 <li>
6287 <p><a class='existingWikiWord' href='/nlab/show/geometric+quantization'>…
6288 </li>
6289
6290 <li>
6291 <p><a class='existingWikiWord' href='/nlab/show/deformation+quantization…
6292 </li>
6293
6294 <li>
6295 <p><a class='existingWikiWord' href='/nlab/show/path+integral'>path inte…
6296 </li>
6297
6298 <li>
6299 <p><a class='existingWikiWord' href='/nlab/show/semiclassical+approximat…
6300 </li>
6301 </ul>
6302 </li>
6303
6304 <li>
6305 <p><strong><a class='existingWikiWord' href='/nlab/show/quantum+field+th…
6306
6307 <ul>
6308 <li>
6309 <p>Axiomatizations</p>
6310
6311 <ul>
6312 <li>
6313 <p><a class='existingWikiWord' href='/nlab/show/AQFT'>algebraic QFT</a><…
6314
6315 <ul>
6316 <li>
6317 <p><a class='existingWikiWord' href='/nlab/show/Wightman+axioms'>Wightma…
6318 </li>
6319
6320 <li>
6321 <p><a class='existingWikiWord' href='/nlab/show/Haag-Kastler+axioms'>Haa…
6322
6323 <ul>
6324 <li>
6325 <p><a class='existingWikiWord' href='/nlab/show/operator+algebra'>operat…
6326 </li>
6327
6328 <li>
6329 <p><a class='existingWikiWord' href='/nlab/show/causally+local+net+of+ob…
6330 </li>
6331 </ul>
6332 </li>
6333
6334 <li>
6335 <p><a class='existingWikiWord' href='/nlab/show/conformal+net'>conformal…
6336 </li>
6337
6338 <li>
6339 <p><a class='existingWikiWord' href='/nlab/show/Reeh-Schlieder+theorem'>…
6340 </li>
6341
6342 <li>
6343 <p><a class='existingWikiWord' href='/nlab/show/Osterwalder-Schrader+the…
6344 </li>
6345
6346 <li>
6347 <p><a class='existingWikiWord' href='/nlab/show/PCT+theorem'>PCT theorem…
6348 </li>
6349
6350 <li>
6351 <p><a class='existingWikiWord' href='/nlab/show/Bisognano-Wichmann+theor…
6352
6353 <ul>
6354 <li><a class='existingWikiWord' href='/nlab/show/modular+theory'>modular…
6355 </ul>
6356 </li>
6357
6358 <li>
6359 <p><a class='existingWikiWord' href='/nlab/show/spin-statistics+theorem'…
6360
6361 <ul>
6362 <li><a class='existingWikiWord' href='/nlab/show/boson'>boson</a>, <a cl…
6363 </ul>
6364 </li>
6365 </ul>
6366 </li>
6367
6368 <li>
6369 <p><a class='existingWikiWord' href='/nlab/show/functorial+field+theory'…
6370
6371 <ul>
6372 <li>
6373 <p><a class='existingWikiWord' href='/nlab/show/cobordism'>cobordism</a>…
6374 </li>
6375
6376 <li>
6377 <p><a class='existingWikiWord' href='/nlab/show/%28infinity%2Cn%29-categ…
6378 </li>
6379
6380 <li>
6381 <p><a class='existingWikiWord' href='/nlab/show/cobordism+hypothesis'>co…
6382 </li>
6383
6384 <li>
6385 <p><a class='existingWikiWord' href='/nlab/show/extended+topological+qua…
6386 </li>
6387 </ul>
6388 </li>
6389 </ul>
6390 </li>
6391
6392 <li>
6393 <p>Tools</p>
6394
6395 <ul>
6396 <li>
6397 <p><a class='existingWikiWord' href='/nlab/show/perturbative+quantum+fie…
6398 </li>
6399
6400 <li>
6401 <p><a class='existingWikiWord' href='/nlab/show/effective+quantum+field+…
6402 </li>
6403
6404 <li>
6405 <p><a class='existingWikiWord' href='/nlab/show/renormalization'>renorma…
6406 </li>
6407
6408 <li>
6409 <p><a class='existingWikiWord' href='/nlab/show/BV-BRST+formalism'>BV-BR…
6410 </li>
6411
6412 <li>
6413 <p><a class='existingWikiWord' href='/nlab/show/geometric+infinity-funct…
6414 </li>
6415 </ul>
6416 </li>
6417
6418 <li>
6419 <p><a class='existingWikiWord' href='/nlab/show/particle+physics'>partic…
6420
6421 <ul>
6422 <li>
6423 <p><a class='existingWikiWord' href='/nlab/show/phenomenology'>phenomeno…
6424 </li>
6425
6426 <li>
6427 <p><a class='existingWikiWord' href='/nlab/show/model+%28in+theoretical+…
6428
6429 <ul>
6430 <li>
6431 <p><a class='existingWikiWord' href='/nlab/show/standard+model+of+partic…
6432 </li>
6433
6434 <li>
6435 <p><a class='existingWikiWord' href='/nlab/show/fields+and+quanta+-+tabl…
6436 </li>
6437
6438 <li>
6439 <p><a class='existingWikiWord' href='/nlab/show/GUT'>Grand Unified Theor…
6440 </li>
6441 </ul>
6442 </li>
6443
6444 <li>
6445 <p><a class='existingWikiWord' href='/nlab/show/scattering+amplitude'>sc…
6446
6447 <ul>
6448 <li><a class='existingWikiWord' href='/nlab/show/on-shell+recursion'>on-…
6449 </ul>
6450 </li>
6451 </ul>
6452 </li>
6453
6454 <li>
6455 <p>Structural phenomena</p>
6456
6457 <ul>
6458 <li>
6459 <p><a class='existingWikiWord' href='/nlab/show/universality+class'>univ…
6460 </li>
6461
6462 <li>
6463 <p><a class='existingWikiWord' href='/nlab/show/quantum+anomaly'>quantum…
6464
6465 <ul>
6466 <li><a class='existingWikiWord' href='/nlab/show/Green-Schwarz+mechanism…
6467 </ul>
6468 </li>
6469
6470 <li>
6471 <p><a class='existingWikiWord' href='/nlab/show/instanton'>instanton</a>…
6472 </li>
6473
6474 <li>
6475 <p><a class='existingWikiWord' href='/nlab/show/spontaneously+broken+sym…
6476 </li>
6477
6478 <li>
6479 <p><a class='existingWikiWord' href='/nlab/show/Kaluza-Klein+mechanism'>…
6480 </li>
6481
6482 <li>
6483 <p><a class='existingWikiWord' href='/nlab/show/integrable+system'>integ…
6484 </li>
6485
6486 <li>
6487 <p><a class='existingWikiWord' href='/nlab/show/holonomic+quantum+field'…
6488 </li>
6489 </ul>
6490 </li>
6491
6492 <li>
6493 <p>Types of quantum field thories</p>
6494
6495 <ul>
6496 <li>
6497 <p><a class='existingWikiWord' href='/nlab/show/topological+quantum+fiel…
6498
6499 <ul>
6500 <li>
6501 <p><a class='existingWikiWord' href='/nlab/show/2d+TQFT'>2d TQFT</a></p>
6502 </li>
6503
6504 <li>
6505 <p><a class='existingWikiWord' href='/nlab/show/Dijkgraaf-Witten+theory'…
6506 </li>
6507
6508 <li>
6509 <p><a class='existingWikiWord' href='/nlab/show/Chern-Simons+theory'>Che…
6510 </li>
6511 </ul>
6512 </li>
6513
6514 <li>
6515 <p><a class='existingWikiWord' href='/nlab/show/TCFT'>TCFT</a></p>
6516
6517 <ul>
6518 <li>
6519 <p><a class='existingWikiWord' href='/nlab/show/A-model'>A-model</a>, <a…
6520 </li>
6521
6522 <li>
6523 <p><a class='existingWikiWord' href='/nlab/show/mirror+symmetry'>homolog…
6524 </li>
6525 </ul>
6526 </li>
6527
6528 <li>
6529 <p><a class='existingWikiWord' href='/nlab/show/QFT+with+defects'>QFT wi…
6530 </li>
6531
6532 <li>
6533 <p><a class='existingWikiWord' href='/nlab/show/conformal+field+theory'>…
6534 </li>
6535
6536 <li>
6537 <p><a class='existingWikiWord' href='/nlab/show/%281%2C1%29-dimensional+…
6538 </li>
6539
6540 <li>
6541 <p><a class='existingWikiWord' href='/nlab/show/%282%2C1%29-dimensional+…
6542 </li>
6543
6544 <li>
6545 <p><a class='existingWikiWord' href='/nlab/show/conformal+field+theory'>…
6546
6547 <ul>
6548 <li>
6549 <p><a class='existingWikiWord' href='/nlab/show/Wess-Zumino-Witten+model…
6550 </li>
6551
6552 <li>
6553 <p><a class='existingWikiWord' href='/nlab/show/D%3D6+N%3D%282%2C0%29+SC…
6554 </li>
6555 </ul>
6556 </li>
6557
6558 <li>
6559 <p><a class='existingWikiWord' href='/nlab/show/gauge+theory'>gauge theo…
6560
6561 <ul>
6562 <li>
6563 <p><a class='existingWikiWord' href='/nlab/show/field+strength'>field st…
6564 </li>
6565
6566 <li>
6567 <p><a class='existingWikiWord' href='/nlab/show/gauge+group'>gauge group…
6568 </li>
6569
6570 <li>
6571 <p>examples</p>
6572
6573 <ul>
6574 <li><a class='existingWikiWord' href='/nlab/show/electromagnetic+field'>…
6575 </ul>
6576 </li>
6577
6578 <li>
6579 <p><a class='existingWikiWord' href='/nlab/show/electric+charge'>electri…
6580 </li>
6581
6582 <li>
6583 <p><a class='existingWikiWord' href='/nlab/show/magnetic+charge'>magneti…
6584
6585 <ul>
6586 <li><a class='existingWikiWord' href='/nlab/show/Yang-Mills+field'>Yang-…
6587 </ul>
6588 </li>
6589
6590 <li>
6591 <p><a class='existingWikiWord' href='/nlab/show/Yang-Mills+theory'>Yang-…
6592 </li>
6593
6594 <li>
6595 <p><a class='existingWikiWord' href='/nlab/show/The+Dirac+Electron'>spin…
6596 </li>
6597
6598 <li>
6599 <p><a class='existingWikiWord' href='/nlab/show/topological+Yang-Mills+t…
6600
6601 <ul>
6602 <li><a class='existingWikiWord' href='/nlab/show/Kalb-Ramond+field'>Kalb…
6603
6604 <li><a class='existingWikiWord' href='/nlab/show/supergravity+C-field'>s…
6605
6606 <li><a class='existingWikiWord' href='/nlab/show/RR+field'>RR field</a><…
6607
6608 <li><a class='existingWikiWord' href='/nlab/show/first-order+formulation…
6609 </ul>
6610 </li>
6611
6612 <li>
6613 <p><a class='existingWikiWord' href='/nlab/show/general+covariance'>gene…
6614 </li>
6615
6616 <li>
6617 <p><a class='existingWikiWord' href='/nlab/show/supergravity'>supergravi…
6618 </li>
6619
6620 <li>
6621 <p><a class='existingWikiWord' href='/nlab/show/D%27Auria-Fre+formulatio…
6622 </li>
6623
6624 <li>
6625 <p><a class='existingWikiWord' href='/nlab/show/gravity+as+a+BF+theory'>…
6626 </li>
6627 </ul>
6628 </li>
6629
6630 <li>
6631 <p><a class='existingWikiWord' href='/nlab/show/sigma-model'>sigma-model…
6632
6633 <ul>
6634 <li>
6635 <p><a class='existingWikiWord' href='/nlab/show/particle'>particle</a>, …
6636 </li>
6637
6638 <li>
6639 <p><a class='existingWikiWord' href='/nlab/show/string'>string</a>, <a c…
6640 </li>
6641
6642 <li>
6643 <p><a class='existingWikiWord' href='/nlab/show/membrane'>membrane</a></…
6644 </li>
6645
6646 <li>
6647 <p><a class='existingWikiWord' href='/nlab/show/AKSZ+sigma-model'>AKSZ t…
6648 </li>
6649 </ul>
6650 </li>
6651 </ul>
6652 </li>
6653 </ul>
6654 </li>
6655
6656 <li>
6657 <p><a class='existingWikiWord' href='/nlab/show/string+theory'>String Th…
6658
6659 <ul>
6660 <li><a class='existingWikiWord' href='/nlab/show/string+theory+results+a…
6661 </ul>
6662 </li>
6663
6664 <li>
6665 <p><a class='existingWikiWord' href='/nlab/show/number+theory+and+physic…
6666
6667 <ul>
6668 <li><a class='existingWikiWord' href='/nlab/show/Riemann+hypothesis+and+…
6669 </ul>
6670 </li>
6671 </ul>
6672 <div>
6673 <p>
6674 <a href='/nlab/edit/physicscontents'>Edit this sidebar</a>
6675 </p>
6676 </div></div>
6677 </div>
6678 </div>
6679
6680 <h1 id='contents'>Contents</h1>
6681 <div class='maruku_toc'><ul><li><a href='#idea'>Idea</a></li><li><a href…
6682 <h2 id='idea'>Idea</h2>
6683
6684 <p>Our <a class='existingWikiWord' href='/nlab/show/galaxy'>galaxy</a>.<…
6685
6686 <h2 id='references'>References</h2>
6687
6688 <ul>
6689 <li>Susan Gardner, Samuel D. McDermott, Brian Yanny, <em>The Milky Way, …
6690 </ul>
6691
6692 <p>See also</p>
6693
6694 <ul>
6695 <li>Wikipedia, <em><a href='https://en.wikipedia.org/wiki/Milky_Way'>Mil…
6696 </ul> </div>
6697 </content>
6698 </entry>
6699 </feed>
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