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 161272
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.
3
votes
Accepted
Group cohomology of Q/Z
Short answer:
$$
H^i(\mathbb{Q}/\mathbb{Z}) =
\begin{cases}
\mathbb{Z}, & i = 0,\\
0, & i \equiv 1 \mod 2,\\
A, & i\equiv 0 \mod 2, i>1,
\end{cases}$$
where $A$ fits into a short exact sequence $\mat …
