mathlib3

3dec44d0 - feat(representation_theory/group_cohomology_resolution): add isomorphism with nth inhomogeneous cochains (#18159)

feat(representation_theory/group_cohomology_resolution): add isomorphism with nth inhomogeneous cochains (#18159) Given a $k$-linear $G$-representation $A,$ this defines the $k$-linear isomorphism between functions $G^n \to A$ and representation morphisms $Hom(k[G^{n + 1}], A),$ called `Rep.diagonal_hom_equiv`. Co-authored-by: Joël Riou <joel.riou@universite-paris-saclay.fr>