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Project-declaredLean 4.33.0-rc1 · mathlib@6c5a9081e9b7

Infl δ naturality

groupCohomology.infl_δ_naturality

Plain-language statement

Assume that we have a short exact sequence 0 → A → B → C → 0 in Rep R G and that the sequence of H- invariants is also a short exact in Rep R (G ⧸ H) : 0 → Aᴴ → Bᴴ → Cᴴ → 0. Then we have a commuting square Hⁿ(G ⧸ H, Cᴴ) ⟶ H^{n+1}(G ⧸ H, Aᴴ) | | ↓ ↓ Hⁿ(G , C) ⟶ H^{n+1}(G,A) where the horizontal maps are connecting homomorphisms an...

Exact Lean statement

lemma infl_δ_naturality {S : ShortComplex (Rep R G)} (hS : S.ShortExact)
    (hS' : (S.map (quotientToInvariantsFunctor' surj)).ShortExact) (i j : ℕ) (hij : i + 1 = j) :
    δ hS' i j hij ≫ (infl surj j).app _ = (infl surj i).app _ ≫ δ hS i j hij

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
lemma infl_δ_naturality {S : ShortComplex (Rep R G)} (hS : S.ShortExact)    (hS' : (S.map (quotientToInvariantsFunctor' surj)).ShortExact) (i j : ) (hij : i + 1 = j) :    δ hS' i j hij ≫ (infl surj j).app _ = (infl surj i).app _ ≫ δ hS i j hij    := by  let C := S.map (cochainsFunctor R G)  let S' := S.map (quotientToInvariantsFunctor' surj)  let C' := S'.map (cochainsFunctor R Q)  let φ : C' ⟶ C := {    τ₁ := (cochain_infl surj).app S.X    τ₂ := (cochain_infl surj).app S.X    τ₃ := (cochain_infl surj).app S.X    comm₁₂ := ((cochain_infl surj).naturality S.f).symm    comm₂₃ := ((cochain_infl surj).naturality S.g).symm  }  have ses₁ : C.ShortExact := map_cochainsFunctor_shortExact hS  have ses₂ : C'.ShortExact := map_cochainsFunctor_shortExact hS'  exact HomologySequence.δ_naturality φ ses₂ ses₁ i j hij
Project
Class Field Theory
License
Apache-2.0
Commit
f18cd7fd1575
Source
ClassFieldTheory/Cohomology/Functors/Inflation.lean:131-147

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Related declarations

Project-declaredLean 4.33.0-rc1

Exists of surjective

groupCohomology.exists_of_surjective

Plain-language statement

Given map f: M ⟶ N and q : ℕ, if H^{q+1}(M) ⟶ H^{q+1}(N) is surjective, then any z : Z^{q+1}(N) can be written as f(z') + d(y) for some z' : Z^{q+1}(M) and y : C^q(M). Note that d is spelled as toCocycles.

number theoryclass field theorylocal fields

Source project: Class Field Theory

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