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Atlas.AlgebraicGeometryI.code.LongExactSequence

The connecting homomorphism H_i(C) → H_j(A) of the long exact homology sequence arising from a short exact sequence of complexes.

Instances For

    Exactness of the long exact sequence at H_i(B).

    theorem LongExactSequence.long_exact_sequence_exact_at_Hi_C {C : Type u} [CategoryTheory.Category.{v, u} C] [CategoryTheory.Abelian C] {ι : Type u_1} {c : ComplexShape ι} {S : CategoryTheory.ShortComplex (HomologicalComplex C c)} (hS : S.ShortExact) (i j : ι) (hij : c.Rel i j) :
    { X₁ := S.X₂.homology i, X₂ := S.X₃.homology i, X₃ := S.X₁.homology j, f := HomologicalComplex.homologyMap S.g i, g := hS.δ i j hij, zero := }.Exact

    Exactness of the long exact sequence at H_i(C).

    theorem LongExactSequence.long_exact_sequence_exact_at_Hj_A {C : Type u} [CategoryTheory.Category.{v, u} C] [CategoryTheory.Abelian C] {ι : Type u_1} {c : ComplexShape ι} {S : CategoryTheory.ShortComplex (HomologicalComplex C c)} (hS : S.ShortExact) (i j : ι) (hij : c.Rel i j) :
    { X₁ := S.X₃.homology i, X₂ := S.X₁.homology j, X₃ := S.X₂.homology j, f := hS.δ i j hij, g := HomologicalComplex.homologyMap S.f j, zero := }.Exact

    Exactness of the long exact sequence at H_j(A).

    theorem LongExactSequence.long_exact_sequence {C : Type u} [CategoryTheory.Category.{v, u} C] [CategoryTheory.Abelian C] {ι : Type u_1} {c : ComplexShape ι} {S : CategoryTheory.ShortComplex (HomologicalComplex C c)} (hS : S.ShortExact) (i j : ι) (hij : c.Rel i j) :
    { X₁ := S.X₁.homology i, X₂ := S.X₂.homology i, X₃ := S.X₃.homology i, f := HomologicalComplex.homologyMap S.f i, g := HomologicalComplex.homologyMap S.g i, zero := }.Exact { X₁ := S.X₂.homology i, X₂ := S.X₃.homology i, X₃ := S.X₁.homology j, f := HomologicalComplex.homologyMap S.g i, g := hS.δ i j hij, zero := }.Exact { X₁ := S.X₃.homology i, X₂ := S.X₁.homology j, X₃ := S.X₂.homology j, f := hS.δ i j hij, g := HomologicalComplex.homologyMap S.f j, zero := }.Exact

    The long exact (co)homology sequence: from a short exact sequence of complexes, exactness holds at H_i(B), H_i(C), and H_j(A).

    If H_i(B) = 0, the connecting homomorphism δ is a monomorphism.

    If H_j(B) = 0, the connecting homomorphism δ is an epimorphism.

    If both H_i(B) and H_j(B) vanish, the connecting δ is an isomorphism.