Documentation

TauCeti.AlgebraicTopology.Cohomology.Twisted.Relative

Relative singular cohomology with local coefficients #

Let (X, A) be a topological pair and let L be a local coefficient system of R-modules on X. Applying Hom(-, M) to the relative twisted chains of the pair gives its relative twisted cochain complex, whose cohomology is the relative singular cohomology of (X, A) with coefficients in L and values in M.

The twisted chains of A sit inside those of X as the summands indexed by the singular simplices of A, so that inclusion is split in each degree. Applying Hom(-, M) to the short exact sequence 0 ⟶ C(A; L) ⟶ C(X; L) ⟶ C(X, A; L) ⟶ 0 therefore again gives a short exact sequence

0 ⟶ C*(X, A; L) ⟶ C*(X; L) ⟶ C*(A; L) ⟶ 0,

and its long exact cohomology sequence is the long exact sequence of the pair with local coefficients. This is the sequence in which the cap product with the orientation system expresses Poincaré--Lefschetz duality, so the twisted theory, and not only the untwisted one of TauCeti.AlgebraicTopology.Cohomology.Relative, is needed.

Main declarations #

References #

@[reducible, inline]

The relative singular cochain complex of a topological pair with coefficients in a local coefficient system L on its ambient space and values in M: in degree n, the k-module of morphisms from the relative twisted n-chains to M.

Equations
Instances For
    @[reducible, inline]
    noncomputable abbrev TopPair.twistedCohomology {R : Type u} [Ring R] (P : TopPair) (L : TauCeti.LocalCoefficientSystem R fst) (k : Type u_1) [Ring k] [CategoryTheory.Linear k (ModuleCat R)] (M : ModuleCat R) (n : ℕ) :

    The relative singular cohomology of a topological pair in degree n, with coefficients in a local coefficient system on its ambient space and values in M.

    Equations
    Instances For
      @[reducible, inline]

      The cochain map on relative twisted cochains induced by a morphism of local coefficient systems.

      Equations
      Instances For
        @[simp]

        The degree-n component of the relative cochain map induced by a morphism of local coefficient systems acts by precomposition.

        @[reducible, inline]
        noncomputable abbrev TopPair.twistedCohomologyCoefficientMap {R : Type u} [Ring R] (P : TopPair) (k : Type u_1) [Ring k] [CategoryTheory.Linear k (ModuleCat R)] (M : ModuleCat R) {L K : TauCeti.LocalCoefficientSystem R fst} (η : L ⟶ K) (n : ℕ) :

        The map on relative twisted cohomology induced by a morphism of local coefficient systems.

        Equations
        Instances For
          @[reducible, inline]

          The twisted cochain sequence C*(X, A; L) ⟶ C*(X; L) ⟶ C*(A; L) of a topological pair (X, A): the image under Hom(-, M) of the twisted chain sequence of the pair.

          Equations
          Instances For

            The first map of the twisted cochain sequence of a pair is the image under Hom(-, M) of the quotient map from ambient to relative twisted chains.

            The second map of the twisted cochain sequence of a pair is restriction from the ambient space to the subspace.

            The twisted cochain sequence 0 ⟶ C*(X, A; L) ⟶ C*(X; L) ⟶ C*(A; L) ⟶ 0 of a topological pair is short exact.

            @[reducible, inline]

            The map Hⁿ(X, A; L) ⟶ Hⁿ(X; L) from relative to absolute twisted cohomology.

            Equations
            Instances For
              @[reducible, inline]
              noncomputable abbrev TopPair.twistedCohomologyδ {R : Type u} [Ring R] (P : TopPair) (L : TauCeti.LocalCoefficientSystem R fst) (k : Type u_1) [Ring k] [CategoryTheory.Linear k (ModuleCat R)] (M : ModuleCat R) (n m : ℕ) (h : n + 1 = m := by lia) :

              The connecting morphism Hⁿ(A; L) ⟶ Hᵐ(X, A; L) of the long exact sequence of a topological pair, where n + 1 = m.

              Equations
              Instances For
                theorem TopPair.twistedCohomology_exact_relative {R : Type u} [Ring R] (P : TopPair) (L : TauCeti.LocalCoefficientSystem R fst) (k : Type u_1) [Ring k] [CategoryTheory.Linear k (ModuleCat R)] (M : ModuleCat R) (n m : ℕ) (h : n + 1 = m := by lia) :

                Exactness at relative cohomology: Hⁿ(A; L) ⟶ Hᵐ(X, A; L) ⟶ Hᵐ(X; L) is exact for n + 1 = m.

                Exactness at ambient cohomology: Hⁿ(X, A; L) ⟶ Hⁿ(X; L) ⟶ Hⁿ(A; L) is exact.

                Exactness at subspace cohomology: Hⁿ(X; L) ⟶ Hⁿ(A; L) ⟶ Hᵐ(X, A; L) is exact for n + 1 = m.

                The map from relative to absolute twisted cohomology is a monomorphism in degree zero.

                The morphism between the twisted cochain sequences of a pair induced by a morphism of local coefficient systems.

                Equations
                • One or more equations did not get rendered due to their size.
                Instances For

                  The map from relative to absolute twisted cohomology commutes with a change of local coefficient system.

                  The connecting morphism of the long exact sequence in relative twisted cohomology commutes with a change of local coefficient system.

                  The connecting morphism of the long exact sequence in relative twisted cohomology commutes with a change of local coefficient system.

                  @[reducible, inline]

                  The cochain map on relative twisted cochains induced by a map of topological pairs.

                  Equations
                  Instances For
                    @[simp]

                    The degree-n component of the relative cochain map induced by a map of pairs acts by precomposition with the induced morphism of relative twisted chains.

                    @[reducible, inline]

                    The map on relative twisted cohomology induced by a map of topological pairs.

                    Equations
                    Instances For
                      @[simp]

                      The identity map of a pair induces on relative twisted cochains the coefficient-change map coming from the canonical identification of a system with its pullback along the identity.

                      @[simp]

                      Maps of relative twisted cochain complexes respect composition of maps of pairs, after the canonical comparison between pullback along a composite and iterated pullback.

                      @[reducible, inline]

                      The cochain map on subspace twisted cochains induced by a map of pairs: restriction along the subspace component, after the canonical comparison of the pulled-back coefficient systems.

                      Equations
                      Instances For

                        The morphism between the twisted cochain sequences of two pairs induced by a map of pairs.

                        Equations
                        • One or more equations did not get rendered due to their size.
                        Instances For

                          The connecting morphism of the long exact sequence in relative twisted cohomology is natural in maps of topological pairs.

                          The connecting morphism of the long exact sequence in relative twisted cohomology is natural in maps of topological pairs.

                          For a constant local coefficient system, the relative twisted cochain complex of a pair is the ordinary relative singular cochain complex with the same coefficient module.

                          Equations
                          Instances For

                            For a constant local coefficient system, relative twisted cohomology is ordinary relative singular cohomology.

                            Equations
                            Instances For