Documentation

Mathlib.Algebra.Homology.ShortComplex.PreservesHomology

Functors which preserves homology #

If F : C ⥤ D is a functor between categories with zero morphisms, we shall say that F preserves homology when F preserves both kernels and cokernels. This typeclass is named [F.PreservesHomology], and is automatically satisfied when F preserves both finite limits and finite colimits.

If S : ShortComplex C and [F.PreservesHomology], then there is an isomorphism S.mapHomologyIso F : (S.map F).homology ≅ F.obj S.homology, which is part of the natural isomorphism homologyFunctorIso F between the functors F.mapShortComplex ⋙ homologyFunctor D and homologyFunctor C ⋙ F.

A functor preserves homology when it preserves both kernels and cokernels.

Instances

    A left homology data h of a short complex S is preserved by a functor F is F preserves the kernel of S.g : S.X₂ ⟶ S.X₃ and the cokernel of h.f' : S.X₁ ⟶ h.K.

    Instances

      When a left homology data h of a short complex S is preserved by a functor F, this is the induced left homology data h.map F for the short complex S.map F.

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

        Given a left homology map data ψ : LeftHomologyMapData φ h₁ h₂ such that both left homology data h₁ and h₂ are preserved by a functor F, this is the induced left homology map data for the morphism F.mapShortComplex.map φ.

        Equations
        Instances For

          A right homology data h of a short complex S is preserved by a functor F is F preserves the cokernel of S.f : S.X₁ ⟶ S.X₂ and the kernel of h.g' : h.Q ⟶ S.X₃.

          Instances

            When a right homology data h of a short complex S is preserved by a functor F, this is the induced right homology data h.map F for the short complex S.map F.

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

              Given a right homology map data ψ : RightHomologyMapData φ h₁ h₂ such that both right homology data h₁ and h₂ are preserved by a functor F, this is the induced right homology map data for the morphism F.mapShortComplex.map φ.

              Equations
              Instances For

                When a homology data h of a short complex S is such that both h.left and h.right are preserved by a functor F, this is the induced homology data h.map F for the short complex S.map F.

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

                  A functor preserves the left homology of a short complex S if it preserves all the left homology data of S.

                  Instances

                    A functor preserves the right homology of a short complex S if it preserves all the right homology data of S.

                    Instances

                      When a functor F preserves the left homology of a short complex S, this is the canonical isomorphism (S.map F).cycles ≅ F.obj S.cycles.

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

                        When a functor F preserves the left homology of a short complex S, this is the canonical isomorphism (S.map F).leftHomology ≅ F.obj S.leftHomology.

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

                          When a functor F preserves the right homology of a short complex S, this is the canonical isomorphism (S.map F).opcycles ≅ F.obj S.opcycles.

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

                            When a functor F preserves the right homology of a short complex S, this is the canonical isomorphism (S.map F).rightHomology ≅ F.obj S.rightHomology.

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

                              Given a natural transformation τ : F ⟶ G between functors C ⥤ D which preserve the left homology of a short complex S, and a left homology data for S, this is the left homology map data for the morphism S.mapNatTrans τ obtained by evaluating τ.

                              Equations
                              Instances For

                                Given a natural transformation τ : F ⟶ G between functors C ⥤ D which preserve the right homology of a short complex S, and a right homology data for S, this is the right homology map data for the morphism S.mapNatTrans τ obtained by evaluating τ.

                                Equations
                                Instances For

                                  If a short complex S is such that S.f = 0 and that the kernel of S.g is preserved by a functor F, then F preserves the left homology of S.

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

                                    If a short complex S is such that S.g = 0 and that the cokernel of S.f is preserved by a functor F, then F preserves the right homology of S.

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

                                      If a short complex S is such that S.g = 0 and that the cokernel of S.f is preserved by a functor F, then F preserves the left homology of S.

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

                                        If a short complex S is such that S.f = 0 and that the kernel of S.g is preserved by a functor F, then F preserves the right homology of S.

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