Kernel and cokernel of the differential of a spectral object #
Let X be a spectral object indexed by the category ι
in the abelian category C. In this file, we introduce
the kernel X.cycles and the cokernel X.opcycles of X.δ.
These are defined when f and g are composable morphisms
in ι and for any integer n.
In the documentation, the kernel X.cycles n f g of
δ : H^n(g) ⟶ H^{n+1}(f) shall be denoted Z^n(f, g),
and the cokernel X.opcycles n f g of δ : H^{n-1}(g) ⟶ H^n(f)
shall be denoted opZ^n(f, g).
The definitions cyclesMap and opcyclesMap give the
functoriality of these definitions with respect
to morphisms in ComposableArrows ι 2.
We record that Z^n(f, g) is a kernel by the lemma
kernelSequenceCycles_exact and that opZ^n(f, g) is
a cokernel by the lemma cokernelSequenceOpcycles_exact.
We also provide a constructor X.liftCycles for morphisms
to cycles and X.descOpcycles for morphisms from opcycles.
References #
- [Jean-Louis Verdier, Des catégories dérivées des catégories abéliennes, II.4][verdier1996]
The kernel of δ : H^n(g) ⟶ H^{n+1}(f). In the documentation,
this may be shortened as Z^n(f, g)
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The cokernel of δ : H^{n-1}(g) ⟶ H^n(g). In the documentation,
this may be shortened as opZ^n₁(f, g).
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The inclusion Z^n(f, g) ⟶ H^n(g) of the kernel of δ.
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The projection H^n(f) ⟶ opZ^n(f, g) to the cokernel of δ.
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The short complex which expresses X.cycles as the kernel of X.δ.
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The short complex which expresses X.opcycles as the cokernel of X.δ.
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Constructor for morphisms to X.cycles.
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Constructor for morphisms from X.opcycles.
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The functoriality of X.cycles with respect to morphisms in
ComposableArrows ι 2.
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The functoriality of X.opcycles with respect to morphisms in
ComposableArrows ι 2.
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X.cycles also identifies to a cokernel. More precisely,
Z^n(f, g) identifies to the cokernel of H^n(f) ⟶ H^n(f ≫ g)
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X.opcycles also identifies to a kernel. More precisely,
opZ(f, g) identifies to the kernel of H^n(f ≫ g) ⟶ H^n(g)
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The map H^n(fg) ⟶ H^n(g) factors through Z^n(f, g).
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The map H^n(f) ⟶ H^n(f ≫ g) factors through opZ^n(f, g).
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The short complex expressing Z^n(f, g) as a cokernel of
the map H^n(f) ⟶ H^n(f ≫ g).
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The short complex expressing opZ^n(f, g) as a kernel of
the map H^n(f ≫ g) ⟶ H^n(g).
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Z^n(f, g) identifies to a cokernel of the H^n(f) ⟶ H^n(f ≫ g).
opZ^n(f, g) identifies to the kernel of H^n(f ≫ g) ⟶ H^n(g).
Constructor for morphisms from X.cycles.
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Constructor for morphisms to X.opcycles.
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The morphism H^{n₀}(f₃) ⟶ Z^{n₁}(f₁, f₂) induced by δ
when f₁, f₂, f₃ are composable morphisms and n₀ + 1 = n₁.
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The morphism opZ^{n₀}(f₂, f₃) ⟶ H^{n₁}(f₁) induced by δ
when f₁, f₂, f₃ are composable morphisms and n₀ + 1 = n₁.