feat(RepresentationTheory/Homological/GroupHomology/LongExactSequence): specialise LES API to low degree group homology#21766
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101damnations wants to merge 239 commits intomasterfrom
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feat(RepresentationTheory/Homological/GroupHomology/LongExactSequence): specialise LES API to low degree group homology#21766101damnations wants to merge 239 commits intomasterfrom
101damnations wants to merge 239 commits intomasterfrom
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added 30 commits
January 22, 2025 14:37
added 23 commits
February 12, 2025 18:47
…mathlib4 into coinvariantsstuffhalf
…-community/mathlib4 into coinvariantsstuff
…mathlib4 into diagonalsuccisohalf
…ommunity/mathlib4 into diagonalsucciso
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Refactored and moved to a fork in #25943. |
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Given a commutative ring
kand a groupG, this file shows that a short exact sequence ofk-linearG-representations0 ⟶ X₁ ⟶ X₂ ⟶ X₃ ⟶ 0induces a short exact sequence ofcomplexes of inhomogeneous chains
0 ⟶ C(X₁) ⟶ C(X₂) ⟶ C(X₃) ⟶ 0, whereHₙ(C(Xᵢ))is the
nth group homology ofXᵢ.This allows us to specialize API about long exact sequences to group homology; in this PR we focus on degrees
n = 0, 1, 2.Action.rhoaMonoidHominstead of a morphism inMonCat#21652Finsupp#21732Rep.diagonal k G (n + 1) ≅ Rep.free k G (Fin n → G)#21736IsOneCyclepredicate and friends #21757groupHomology A nwithHn Aforn = 0, 1, 2#21759