Search Results
| Search type | Search syntax |
|---|---|
| Tags | [tag] |
| Exact | "words here" |
| Author |
user:1234 user:me (yours) |
| Score |
score:3 (3+) score:0 (none) |
| Answers |
answers:3 (3+) answers:0 (none) isaccepted:yes hasaccepted:no inquestion:1234 |
| Views | views:250 |
| Code | code:"if (foo != bar)" |
| Sections |
title:apples body:"apples oranges" |
| URL | url:"*.example.com" |
| Saves | in:saves |
| Status |
closed:yes duplicate:no migrated:no wiki:no |
| Types |
is:question is:answer |
| Exclude |
-[tag] -apples |
| For more details on advanced search visit our help page | |
Results tagged with group-cohomology
Search options not deleted
user 184
In mathematics, group cohomology is a set of mathematical tools used to study groups using cohomology theory, a technique from algebraic topology. Analogous to group representations, group cohomology looks at the group actions of a group G in an associated G-module M to elucidate the properties of the group.
10
votes
Accepted
Group cohomology vs. topological cohomology in the case of non-trivial action
This is an example of twisted cohomology. In general, for a generalized cohomology theory (spectrum) E and a space X you can talk about E-twists over X. This is a certain structure on X. Given a parti …
- 27.5k
4
votes
Common Computations in Group Cohomology
The automorphisms of this extension are basically the same as group cohomology $H^1(B; A)$, so I will focus on that first.
So we want to show that this must be zero given that B and A are finite abel …
- 27.5k
10
votes
1
answer
280
views
Induced map on $H_4$ of Eilenberg–MacLane spaces
$\DeclareMathOperator\Hom{Hom}$It is well-known (see Breen, Mikhailov, Touzé - Derived functors of the divided power functors for example) that for $A$ a free abelian group we have
$$ H_i(K(A,1); \mat …
- 27.5k
21
votes
Accepted
Is super-vector spaces a "universal central extension" of vector spaces?
This will be a little imprecise, but hopefully if you need a precise result like this you can fill in the details.
First of all Vect has not only the symmetric monoidal structure but also the direct …
- 27.5k
6
votes
Accepted
A tensor category need not be isomorphic to a strict tensor category
First consider the category $\mathcal{C}_G$ with its bifunctor $\otimes$ and unit. How many ways are there to enhance this to a monoidal category structure? The missing data are precisely the associat …
- 27.5k
10
votes
Accepted
Classifying Space of a Group Extension
Yes. The principal bundles are the same and your guess that $BA$ is an abelian group is exactly right. A good reference for this story, and of Segal's result that David Roberts quotes, is Segal's pape …
- 27.5k