Documentation

TauCeti.Algebra.Homology.DG.Module.Right.Hom.Complex

The Hom complex of differential graded right modules #

For two right modules over a differential graded algebra, the degree-p cochains are the right-module linear maps which raise internal degree by p. Their differential is the graded commutator

\delta(f) = d_N \circ f - (-1)^p f \circ d_M.

The right-module convention is important here: homogeneous cochains are ordinary A\^op-linear maps. The two Leibniz terms involving the differential of the algebra cancel in the displayed commutator, so it is again A\^op-linear and has degree p + 1. This file packages these cochains and their differential as a cochain complex of modules over the ground ring. Its degree-zero cocycles are exactly TauCeti.DGRightModuleHom.

Main definitions #

Implementation notes #

dgRightModuleHomComplex is exposed because the component types of its public differential application lemma reduce to the advertised homogeneous-cochain modules. The element-level API is given by dgRightModuleCochains.differential_apply.

References #

def TauCeti.dgRightModuleCochains {R : Type uR} {A : Type uA} {M : Type uM} {N : Type uN} [CommRing R] [Ring A] [Algebra R A] [AddCommGroup M] [Module R M] [Module Aᵐᵒᵖ M] [IsScalarTower R Aᵐᵒᵖ M] [AddCommGroup N] [Module R N] [Module Aᵐᵒᵖ N] [IsScalarTower R Aᵐᵒᵖ N] {ℳ : ℤ → Submodule R M} {ℳN : ℤ → Submodule R N} (p : ℤ) :

The R-submodule of right-module maps of degree p between two differential graded right modules. The differential does not enter the definition; it supplies the differential between successive cochain modules below.

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    @[simp]
    theorem TauCeti.dgRightModuleCochains.mem_iff {R : Type uR} {A : Type uA} {M : Type uM} {N : Type uN} [CommRing R] [Ring A] [Algebra R A] [AddCommGroup M] [Module R M] [Module Aᵐᵒᵖ M] [IsScalarTower R Aᵐᵒᵖ M] [AddCommGroup N] [Module R N] [Module Aᵐᵒᵖ N] [IsScalarTower R Aᵐᵒᵖ N] {ℳ : ℤ → Submodule R M} {ℳN : ℤ → Submodule R N} {p : ℤ} {f : M →ₗ[Aᵐᵒᵖ] N} :
    theorem TauCeti.dgRightModuleCochains.map_mem {R : Type uR} {A : Type uA} {M : Type uM} {N : Type uN} [CommRing R] [Ring A] [Algebra R A] [AddCommGroup M] [Module R M] [Module Aᵐᵒᵖ M] [IsScalarTower R Aᵐᵒᵖ M] [AddCommGroup N] [Module R N] [Module Aᵐᵒᵖ N] [IsScalarTower R Aᵐᵒᵖ N] {ℳ : ℤ → Submodule R M} {ℳN : ℤ → Submodule R N} {p q : ℤ} (f : ↥(dgRightModuleCochains p)) {x : M} (hx : x ∈ ℳ q) :
    ↑f x ∈ ℳN (q + p)

    A homogeneous right-module cochain applied to an element of degree q has degree q + p.

    def TauCeti.dgRightModuleCochains.gradedCommutator {R : Type uR} {A : Type uA} {M : Type uM} {N : Type uN} [CommRing R] [Ring A] [Algebra R A] [AddCommGroup M] [Module R M] [Module Aᵐᵒᵖ M] [IsScalarTower R Aᵐᵒᵖ M] [AddCommGroup N] [Module R N] [Module Aᵐᵒᵖ N] [IsScalarTower R Aᵐᵒᵖ N] {d : A →ₗ[R] A} {ℳ : ℤ → Submodule R M} [DirectSum.Decomposition ℳ] {dM : M →ₗ[R] M} {ℳN : ℤ → Submodule R N} {dN : N →ₗ[R] N} (hMh : LinearMap.IsHomogeneous dM ℳ ℳ 1) (hMl : ∀ {q : ℤ} {x : M}, x ∈ ℳ q → ∀ (a : A), dM (MulOpposite.op a • x) = MulOpposite.op a • dM x + q.negOnePow • MulOpposite.op (d a) • x) (hNh : LinearMap.IsHomogeneous dN ℳN ℳN 1) (hNl : ∀ {q : ℤ} {x : N}, x ∈ ℳN q → ∀ (a : A), dN (MulOpposite.op a • x) = MulOpposite.op a • dN x + q.negOnePow • MulOpposite.op (d a) • x) (p : ℤ) :

    The graded commutator f ↦ dN ∘ f - (-1) ^ p • f ∘ dM on degree-p right-module cochains. It only needs module differentials of degree one obeying the right graded Leibniz rule against the same algebra map d; neither a square-zero nor a curvature equation enters. It is the differential of the Hom complexes of both ordinary and curved differential graded right modules.

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      @[simp]
      theorem TauCeti.dgRightModuleCochains.gradedCommutator_apply {R : Type uR} {A : Type uA} {M : Type uM} {N : Type uN} [CommRing R] [Ring A] [Algebra R A] [AddCommGroup M] [Module R M] [Module Aᵐᵒᵖ M] [IsScalarTower R Aᵐᵒᵖ M] [AddCommGroup N] [Module R N] [Module Aᵐᵒᵖ N] [IsScalarTower R Aᵐᵒᵖ N] {d : A →ₗ[R] A} {ℳ : ℤ → Submodule R M} [DirectSum.Decomposition ℳ] {dM : M →ₗ[R] M} {ℳN : ℤ → Submodule R N} {dN : N →ₗ[R] N} (hMh : LinearMap.IsHomogeneous dM ℳ ℳ 1) (hMl : ∀ {q : ℤ} {x : M}, x ∈ ℳ q → ∀ (a : A), dM (MulOpposite.op a • x) = MulOpposite.op a • dM x + q.negOnePow • MulOpposite.op (d a) • x) (hNh : LinearMap.IsHomogeneous dN ℳN ℳN 1) (hNl : ∀ {q : ℤ} {x : N}, x ∈ ℳN q → ∀ (a : A), dN (MulOpposite.op a • x) = MulOpposite.op a • dN x + q.negOnePow • MulOpposite.op (d a) • x) (p : ℤ) (f : ↥(dgRightModuleCochains p)) (x : M) :
      ↑((gradedCommutator hMh ⋯ hNh ⋯ p) f) x = dN (↑f x) - p.negOnePow • ↑f (dM x)

      Evaluating the graded commutator of a cochain.

      theorem TauCeti.dgRightModuleCochains.gradedCommutator_gradedCommutator_apply {R : Type uR} {A : Type uA} {M : Type uM} {N : Type uN} [CommRing R] [Ring A] [Algebra R A] [AddCommGroup M] [Module R M] [Module Aᵐᵒᵖ M] [IsScalarTower R Aᵐᵒᵖ M] [AddCommGroup N] [Module R N] [Module Aᵐᵒᵖ N] [IsScalarTower R Aᵐᵒᵖ N] {d : A →ₗ[R] A} {ℳ : ℤ → Submodule R M} [DirectSum.Decomposition ℳ] {dM : M →ₗ[R] M} {ℳN : ℤ → Submodule R N} {dN : N →ₗ[R] N} (hMh : LinearMap.IsHomogeneous dM ℳ ℳ 1) (hMl : ∀ {q : ℤ} {x : M}, x ∈ ℳ q → ∀ (a : A), dM (MulOpposite.op a • x) = MulOpposite.op a • dM x + q.negOnePow • MulOpposite.op (d a) • x) (hNh : LinearMap.IsHomogeneous dN ℳN ℳN 1) (hNl : ∀ {q : ℤ} {x : N}, x ∈ ℳN q → ∀ (a : A), dN (MulOpposite.op a • x) = MulOpposite.op a • dN x + q.negOnePow • MulOpposite.op (d a) • x) (p : ℤ) (f : ↥(dgRightModuleCochains p)) (x : M) :
      ↑((gradedCommutator hMh ⋯ hNh ⋯ (p + 1)) ((gradedCommutator hMh ⋯ hNh ⋯ p) f)) x = dN (dN (↑f x)) - ↑f (dM (dM x))

      Applying the graded commutator twice composes the cochain with the squares of the two module differentials: the mixed terms cancel by the sign rule.

      The differential on homogeneous right-module cochains.

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        theorem TauCeti.dgRightModuleCochains.differential_apply {R : Type uR} {A : Type uA} {M : Type uM} {N : Type uN} [CommRing R] [Ring A] [Algebra R A] [AddCommGroup M] [Module R M] [Module Aᵐᵒᵖ M] [IsScalarTower R Aᵐᵒᵖ M] [AddCommGroup N] [Module R N] [Module Aᵐᵒᵖ N] [IsScalarTower R Aᵐᵒᵖ N] {𝒜 : ℤ → Submodule R A} [GradedAlgebra 𝒜] {d : A →ₗ[R] A} {h : IsDGAlgebra 𝒜 d} {ℳ : ℤ → Submodule R M} [SetLike.GradedSMul (InternalGrading.ofDecomposition 𝒜).opposite.piece ℳ] [DirectSum.Decomposition ℳ] {dM : M →ₗ[R] M} {ℳN : ℤ → Submodule R N} [SetLike.GradedSMul (InternalGrading.ofDecomposition 𝒜).opposite.piece ℳN] [DirectSum.Decomposition ℳN] {dN : N →ₗ[R] N} {hM : IsDGRightModule h ℳ dM} {hN : IsDGRightModule h ℳN dN} (p : ℤ) (f : ↥(dgRightModuleCochains p)) (x : M) :
        ↑((differential p) f) x = dN (↑f x) - p.negOnePow • ↑f (dM x)

        Evaluating the differential gives the graded commutator with the module differentials.

        theorem TauCeti.dgRightModuleCochains.differential_comp_self {R : Type uR} {A : Type uA} {M : Type uM} {N : Type uN} [CommRing R] [Ring A] [Algebra R A] [AddCommGroup M] [Module R M] [Module Aᵐᵒᵖ M] [IsScalarTower R Aᵐᵒᵖ M] [AddCommGroup N] [Module R N] [Module Aᵐᵒᵖ N] [IsScalarTower R Aᵐᵒᵖ N] {𝒜 : ℤ → Submodule R A} [GradedAlgebra 𝒜] {d : A →ₗ[R] A} {h : IsDGAlgebra 𝒜 d} {ℳ : ℤ → Submodule R M} [SetLike.GradedSMul (InternalGrading.ofDecomposition 𝒜).opposite.piece ℳ] [DirectSum.Decomposition ℳ] {dM : M →ₗ[R] M} {ℳN : ℤ → Submodule R N} [SetLike.GradedSMul (InternalGrading.ofDecomposition 𝒜).opposite.piece ℳN] [DirectSum.Decomposition ℳN] {dN : N →ₗ[R] N} {hM : IsDGRightModule h ℳ dM} {hN : IsDGRightModule h ℳN dN} (p : ℤ) :

        The differential on right-module cochains squares to zero.

        def TauCeti.dgRightModuleHomComplex {R : Type uR} {A : Type uA} {M : Type uM} {N : Type uN} [CommRing R] [Ring A] [Algebra R A] [AddCommGroup M] [Module R M] [Module Aᵐᵒᵖ M] [IsScalarTower R Aᵐᵒᵖ M] [AddCommGroup N] [Module R N] [Module Aᵐᵒᵖ N] [IsScalarTower R Aᵐᵒᵖ N] {𝒜 : ℤ → Submodule R A} [GradedAlgebra 𝒜] {d : A →ₗ[R] A} {h : IsDGAlgebra 𝒜 d} {ℳ : ℤ → Submodule R M} [SetLike.GradedSMul (InternalGrading.ofDecomposition 𝒜).opposite.piece ℳ] [DirectSum.Decomposition ℳ] {dM : M →ₗ[R] M} {ℳN : ℤ → Submodule R N} [SetLike.GradedSMul (InternalGrading.ofDecomposition 𝒜).opposite.piece ℳN] [DirectSum.Decomposition ℳN] {dN : N →ₗ[R] N} (hM : IsDGRightModule h ℳ dM) (hN : IsDGRightModule h ℳN dN) :

        The Hom complex between two differential graded right modules. Its degree-p term consists of the right-module linear maps raising internal degree by p, and its differential is the graded commutator with the two module differentials.

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          @[simp]
          theorem TauCeti.dgRightModuleHomComplex_X {R : Type uR} {A : Type uA} {M : Type uM} {N : Type uN} [CommRing R] [Ring A] [Algebra R A] [AddCommGroup M] [Module R M] [Module Aᵐᵒᵖ M] [IsScalarTower R Aᵐᵒᵖ M] [AddCommGroup N] [Module R N] [Module Aᵐᵒᵖ N] [IsScalarTower R Aᵐᵒᵖ N] {𝒜 : ℤ → Submodule R A} [GradedAlgebra 𝒜] {d : A →ₗ[R] A} {h : IsDGAlgebra 𝒜 d} {ℳ : ℤ → Submodule R M} [SetLike.GradedSMul (InternalGrading.ofDecomposition 𝒜).opposite.piece ℳ] [DirectSum.Decomposition ℳ] {dM : M →ₗ[R] M} {ℳN : ℤ → Submodule R N} [SetLike.GradedSMul (InternalGrading.ofDecomposition 𝒜).opposite.piece ℳN] [DirectSum.Decomposition ℳN] {dN : N →ₗ[R] N} (hM : IsDGRightModule h ℳ dM) (hN : IsDGRightModule h ℳN dN) (p : ℤ) :

          The degree-p term of the Hom complex is the module of degree-p homogeneous cochains.

          @[simp]

          The differential morphism of the Hom complex is induced by the graded commutator map.

          @[simp]
          theorem TauCeti.dgRightModuleHomComplex_d_apply {R : Type uR} {A : Type uA} {M : Type uM} {N : Type uN} [CommRing R] [Ring A] [Algebra R A] [AddCommGroup M] [Module R M] [Module Aᵐᵒᵖ M] [IsScalarTower R Aᵐᵒᵖ M] [AddCommGroup N] [Module R N] [Module Aᵐᵒᵖ N] [IsScalarTower R Aᵐᵒᵖ N] {𝒜 : ℤ → Submodule R A} [GradedAlgebra 𝒜] {d : A →ₗ[R] A} {h : IsDGAlgebra 𝒜 d} {ℳ : ℤ → Submodule R M} [SetLike.GradedSMul (InternalGrading.ofDecomposition 𝒜).opposite.piece ℳ] [DirectSum.Decomposition ℳ] {dM : M →ₗ[R] M} {ℳN : ℤ → Submodule R N} [SetLike.GradedSMul (InternalGrading.ofDecomposition 𝒜).opposite.piece ℳN] [DirectSum.Decomposition ℳN] {dN : N →ₗ[R] N} (hM : IsDGRightModule h ℳ dM) (hN : IsDGRightModule h ℳN dN) (p : ℤ) (f : ↑((dgRightModuleHomComplex hM hN).X p)) :

          The differential of the Hom complex, evaluated on a homogeneous cochain, is the graded commutator with the module differentials.

          Closed degree-zero cochains in the Hom complex are exactly morphisms of differential graded right modules.

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            @[simp]
            theorem TauCeti.dgRightModuleHomEquivZeroCocycles_apply {R : Type uR} {A : Type uA} {M : Type uM} {N : Type uN} [CommRing R] [Ring A] [Algebra R A] [AddCommGroup M] [Module R M] [Module Aᵐᵒᵖ M] [IsScalarTower R Aᵐᵒᵖ M] [AddCommGroup N] [Module R N] [Module Aᵐᵒᵖ N] [IsScalarTower R Aᵐᵒᵖ N] {𝒜 : ℤ → Submodule R A} [GradedAlgebra 𝒜] {d : A →ₗ[R] A} {h : IsDGAlgebra 𝒜 d} {ℳ : ℤ → Submodule R M} [SetLike.GradedSMul (InternalGrading.ofDecomposition 𝒜).opposite.piece ℳ] [DirectSum.Decomposition ℳ] {dM : M →ₗ[R] M} {ℳN : ℤ → Submodule R N} [SetLike.GradedSMul (InternalGrading.ofDecomposition 𝒜).opposite.piece ℳN] [DirectSum.Decomposition ℳN] {dN : N →ₗ[R] N} (hM : IsDGRightModule h ℳ dM) (hN : IsDGRightModule h ℳN dN) (f : DGRightModuleHom hM hN) (x : M) :
            ↑↑((dgRightModuleHomEquivZeroCocycles hM hN) f) x = f x

            The zero-cocycle associated to a DG right-module morphism has the same underlying map.

            @[simp]
            theorem TauCeti.dgRightModuleHomEquivZeroCocycles_symm_apply {R : Type uR} {A : Type uA} {M : Type uM} {N : Type uN} [CommRing R] [Ring A] [Algebra R A] [AddCommGroup M] [Module R M] [Module Aᵐᵒᵖ M] [IsScalarTower R Aᵐᵒᵖ M] [AddCommGroup N] [Module R N] [Module Aᵐᵒᵖ N] [IsScalarTower R Aᵐᵒᵖ N] {𝒜 : ℤ → Submodule R A} [GradedAlgebra 𝒜] {d : A →ₗ[R] A} {h : IsDGAlgebra 𝒜 d} {ℳ : ℤ → Submodule R M} [SetLike.GradedSMul (InternalGrading.ofDecomposition 𝒜).opposite.piece ℳ] [DirectSum.Decomposition ℳ] {dM : M →ₗ[R] M} {ℳN : ℤ → Submodule R N} [SetLike.GradedSMul (InternalGrading.ofDecomposition 𝒜).opposite.piece ℳN] [DirectSum.Decomposition ℳN] {dN : N →ₗ[R] N} (hM : IsDGRightModule h ℳ dM) (hN : IsDGRightModule h ℳN dN) (f : ↥(dgRightModuleCochains.differential 0).ker) (x : M) :
            ((dgRightModuleHomEquivZeroCocycles hM hN).symm f) x = ↑↑f x

            The DG right-module morphism associated to a zero-cocycle has the same underlying map.

            The identification of DG right-module maps with closed degree-zero cochains is linear.

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              @[simp]
              theorem TauCeti.dgRightModuleHomLinearEquivZeroCocycles_apply {R : Type uR} {A : Type uA} {M : Type uM} {N : Type uN} [CommRing R] [Ring A] [Algebra R A] [AddCommGroup M] [Module R M] [Module Aᵐᵒᵖ M] [IsScalarTower R Aᵐᵒᵖ M] [AddCommGroup N] [Module R N] [Module Aᵐᵒᵖ N] [IsScalarTower R Aᵐᵒᵖ N] {𝒜 : ℤ → Submodule R A} [GradedAlgebra 𝒜] {d : A →ₗ[R] A} {h : IsDGAlgebra 𝒜 d} {ℳ : ℤ → Submodule R M} [SetLike.GradedSMul (InternalGrading.ofDecomposition 𝒜).opposite.piece ℳ] [DirectSum.Decomposition ℳ] {dM : M →ₗ[R] M} {ℳN : ℤ → Submodule R N} [SetLike.GradedSMul (InternalGrading.ofDecomposition 𝒜).opposite.piece ℳN] [DirectSum.Decomposition ℳN] {dN : N →ₗ[R] N} (hM : IsDGRightModule h ℳ dM) (hN : IsDGRightModule h ℳN dN) (f : DGRightModuleHom hM hN) (x : M) :

              The zero-cocycle associated linearly to a DG right-module morphism has the same underlying map.

              @[simp]

              The DG right-module morphism associated linearly to a zero-cocycle has the same underlying map.