Timeline for Tips on cohomology for number theory
Current License: CC BY-SA 2.5
5 events
| when toggle format | what | by | license | comment | |
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| Sep 13, 2021 at 16:47 | history | made wiki | Post Made Community Wiki by Stefan Kohl♦ | ||
| Dec 12, 2009 at 21:04 | comment | added | Kevin Buzzard | @Pete: yes, I know that now. But my confusion was before a pertinent conversation with DC in 1996 :-) | |
| Dec 12, 2009 at 16:53 | comment | added | Pete L. Clark | @kbuzz: The group of order 2 is infinite dimensional in the topological sense: its Eilenberg Mac Lane space is RP^{oo}. But I agree. I learned a little bit of group cohomology first in a finite group theory course (it was used -- only -- to prove the Schur-Zassenhaus Theorem) and it seemed quite bizarre compared to the singular cohomology that I by then knew pretty well. | |
| Dec 12, 2009 at 15:02 | comment | added | Kevin Buzzard | I learnt cohomology this way---first some of the topological/diff manifold theories (de Rham, singular), and then group cohomology. My memory at the time was that I found group cohomology incredibly weird after all the singular cohomology, because an n-dimensional real manifold had all its cohomology vanishing in degrees > n, but the group of order 2 seemed to have cohomology in infinitely many degrees and hence "must be infinite-dimensional". It took me a fair amount of time to get over this! In some sense I wish I'd learned group cohomology first... | |
| Dec 12, 2009 at 2:51 | history | answered | JS Milne | CC BY-SA 2.5 |