Second cohomology group for trivial group action commutes with direct product in second coordinate
Suppose is a group and and are abelian groups. Let , , and denote the Second cohomology group for trivial group action (?) for on , , and the External direct product (?) respectively. Then, we have the following natural isomorphism:
- Kunneth formula for group cohomology: This tells us how to deal with direct products in the first coordinate.