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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.

1 vote

How to show an invariant subfield of rational function field $\mathbb{Q}(x)$ under a certain...

The answer as to the surjectivity of $\alpha$ is no. As in algebraic number theory, the simplest way to prove that an element is not a norm is by local considerations. Let us consider $$ y=\frac{(x^3- …
3 votes

A road map through group cohomology

Chapter 2 of these notes by Milne have been helpful to me.
5 votes
Accepted

First Galois cohomology of Weil restriction of $\mathbb{G}_m$

There is a general argument that is slightly more elementary than what you wrote. By standard properties of Weil restrictions, we have $R(L) = \prod_{\sigma} \mathbb{G}_m(L)$, where the product is tak …
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2 votes

reference for (co)homology theories

I learned sheaf cohomology from Claire Voisin's Hodge Theory and Complex Algebraic Geometry I. This is a great book. As its name suggests, it also spends quite some time explaining Dolbeault cohomolog …
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