Documentation

TauCeti.Geometry.Manifold.DeRham.CompactSupport

Compactly supported de Rham cohomology #

Smooth real-valued forms with compact topological support form a submodule of all smooth forms. The exterior derivative does not enlarge supports, so these forms are a subcomplex of the de Rham complex, the compactly supported de Rham complex; its cohomology is compactly supported de Rham cohomology H^•_c.

A compactly supported closed form has a class in H^•_c; every class arises this way, and a class vanishes exactly when its representative is the exterior derivative of a compactly supported form. The inclusion of complexes induces the comparison H^•_c(M) → H^•_dR(M), which takes the de Rham class of the representative; it is an isomorphism on compact manifolds, where every form is compactly supported.

On a manifold modelled on a finite-dimensional space, every alternating form of degree above the dimension is zero, so H^k_c(M) vanishes for k > dim M.

Pullback along a smooth proper map preserves compact support, so H^•_c is contravariant for smooth proper maps, and a diffeomorphism induces an isomorphism. Pullback along a general smooth map does not preserve compact support: the constant map ℝ → pt pulls the constant function 1 back to a function without compact support.

Main definitions #

References #

The submodule of smooth real-valued k-forms with compact topological support.

Instances For
    @[simp]

    A smooth form is compactly supported when its topological support is compact.

    Transporting the degree of a smooth form preserves compact support.

    @[simp]

    On a compact manifold every smooth form is compactly supported.

    The exterior derivative of a compactly supported smooth form is compactly supported.

    The exterior derivative of compactly supported smooth forms, which does not enlarge supports.

    Instances For
      @[simp]

      The exterior derivative of a compactly supported form is its exterior derivative as a smooth form.

      @[simp]

      Successive exterior derivatives of compactly supported forms compose to zero.

      The compactly supported de Rham complex: compactly supported smooth real-valued forms with the exterior derivative.

      Instances For

        The canonical identification of the degree-k object with compactly supported smooth k-forms.

        Instances For

          Under the canonical identifications of the objects, the differential of the compactly supported de Rham complex is the exterior derivative.

          A closed compactly supported form, viewed in the compactly supported de Rham complex, is killed by the differential.

          @[reducible, inline]
          abbrev TauCeti.compactlySupportedDeRhamCohomology {E : Type u_1} {H : Type u_2} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] (I : ModelWithCorners ℝ E H) (M : Type u_3) [TopologicalSpace M] [ChartedSpace H M] [IsManifold I 2 M] (k : ℕ) :
          Type (max u_1 u_3)

          Compactly supported de Rham cohomology is the categorical homology of the compactly supported de Rham complex.

          Instances For

            The inclusion of the compactly supported de Rham complex into the de Rham complex.

            Instances For

              Under the canonical identifications of the objects, the inclusion is the inclusion of compactly supported forms into smooth forms.

              Under the canonical identifications of the objects, the inclusion is the inclusion of compactly supported forms into smooth forms.

              On a compact manifold the compactly supported de Rham complex is the de Rham complex.

              The submodule of compactly supported closed smooth forms.

              Instances For
                @[simp]

                A smooth form is compactly supported and closed when it is both compactly supported and closed.

                A compactly supported closed form is compactly supported.

                A compactly supported closed form is closed.

                In degree at least the model dimension, every compactly supported form is closed.

                Instances For
                  @[simp]

                  Viewing a top-degree compactly supported form as closed does not change the smooth form.

                  Compactly supported exact forms are exterior derivatives of compactly supported forms in positive degree, and zero in degree zero.

                  Instances For
                    @[simp]

                    There are no nonzero compactly supported exact forms in degree zero.

                    @[simp]

                    In positive degree, compactly supported exact forms are the image of compactly supported forms under the exterior derivative.

                    A compactly supported exact form is exact.

                    A compactly supported exact form is compactly supported and closed.

                    The compactly supported cohomology class of a compactly supported closed form.

                    Instances For

                      The class map is the homology class map of the inclusion of compactly supported closed forms into the compactly supported de Rham complex.

                      Every compactly supported cohomology class is represented by a compactly supported closed form.

                      @[simp]

                      A compactly supported closed form represents zero precisely when it is the exterior derivative of a compactly supported form.

                      The kernel of the class map is the submodule of compactly supported exact forms inside compactly supported closed forms.

                      theorem TauCeti.compactlySupportedDeRhamCohomology.mk_eq_mk_iff {E : Type u_1} {H : Type u_2} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] (I : ModelWithCorners ℝ E H) {M : Type u_3} [TopologicalSpace M] [ChartedSpace H M] [IsManifold I 2 M] (k : ℕ) (φ ψ : ↥(compactlySupportedClosedForms I M k)) :
                      (mk I k) φ = (mk I k) ψ ↔ ↑φ - ↑ψ ∈ exactCompactlySupportedForms I M k

                      Two compactly supported closed forms have the same class precisely when they differ by a compactly supported exact form.

                      The comparison map from compactly supported to ordinary de Rham cohomology, induced on cohomology by the inclusion of complexes.

                      Instances For
                        @[simp]

                        The comparison map sends the class of a compactly supported closed form to the de Rham class of the underlying closed form.

                        On a compact manifold compactly supported and ordinary de Rham cohomology agree.

                        The map induced on cohomology by the inclusion of complexes is the comparison map.

                        Compactly supported cohomology vanishes in degrees above the dimension of the model, where every alternating form is zero.

                        noncomputable def TauCeti.compactlySupportedForms.mpullback {E : Type u_1} {H : Type u_2} {E' : Type u_3} {H' : Type u_4} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] [NormedAddCommGroup E'] [NormedSpace ℝ E'] [TopologicalSpace H'] {I : ModelWithCorners ℝ E H} {I' : ModelWithCorners ℝ E' H'} {M : Type u_7} {M' : Type u_8} [TopologicalSpace M] [ChartedSpace H M] [TopologicalSpace M'] [ChartedSpace H' M'] [IsManifold I 1 M] [IsManifold I' 1 M'] (f : M → M') (hf : ContMDiff I I' (↑⊤) f) (hp : IsProperMap f) (k : ℕ) :

                        Pullback of compactly supported smooth forms along a smooth proper map.

                        Instances For
                          @[simp]
                          theorem TauCeti.compactlySupportedForms.coe_mpullback {E : Type u_1} {H : Type u_2} {E' : Type u_3} {H' : Type u_4} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] [NormedAddCommGroup E'] [NormedSpace ℝ E'] [TopologicalSpace H'] {I : ModelWithCorners ℝ E H} {I' : ModelWithCorners ℝ E' H'} {M : Type u_7} {M' : Type u_8} [TopologicalSpace M] [ChartedSpace H M] [TopologicalSpace M'] [ChartedSpace H' M'] [IsManifold I 1 M] [IsManifold I' 1 M'] (f : M → M') (hf : ContMDiff I I' (↑⊤) f) (hp : IsProperMap f) (k : ℕ) (φ : ↥(compactlySupportedForms I' M' k)) :
                          ↑((mpullback f hf hp k) φ) = (SmoothForm.mpullback f hf) ↑φ

                          The pullback of a compactly supported form is its pullback as a smooth form.

                          @[simp]

                          Pullback of compactly supported forms by the identity is the identity linear map.

                          theorem TauCeti.compactlySupportedForms.mpullback_comp {E : Type u_1} {H : Type u_2} {E' : Type u_3} {H' : Type u_4} {E'' : Type u_5} {H'' : Type u_6} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] [NormedAddCommGroup E'] [NormedSpace ℝ E'] [TopologicalSpace H'] [NormedAddCommGroup E''] [NormedSpace ℝ E''] [TopologicalSpace H''] {I : ModelWithCorners ℝ E H} {I' : ModelWithCorners ℝ E' H'} {I'' : ModelWithCorners ℝ E'' H''} {M : Type u_7} {M' : Type u_8} {M'' : Type u_9} [TopologicalSpace M] [ChartedSpace H M] [TopologicalSpace M'] [ChartedSpace H' M'] [TopologicalSpace M''] [ChartedSpace H'' M''] [IsManifold I 1 M] [IsManifold I' 1 M'] [IsManifold I'' 1 M''] (f : M → M') (g : M' → M'') (hf : ContMDiff I I' (↑⊤) f) (hg : ContMDiff I' I'' (↑⊤) g) (hfp : IsProperMap f) (hgp : IsProperMap g) (k : ℕ) :
                          mpullback (g ∘ f) ⋯ ⋯ k = mpullback f hf hfp k ∘ₗ mpullback g hg hgp k

                          Pullback of compactly supported forms reverses composition.

                          theorem TauCeti.compactlySupportedForms.mextDerivₗ_mpullback {E : Type u_1} {H : Type u_2} {E' : Type u_3} {H' : Type u_4} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] [NormedAddCommGroup E'] [NormedSpace ℝ E'] [TopologicalSpace H'] {I : ModelWithCorners ℝ E H} {I' : ModelWithCorners ℝ E' H'} {M : Type u_7} {M' : Type u_8} [TopologicalSpace M] [ChartedSpace H M] [TopologicalSpace M'] [ChartedSpace H' M'] [IsManifold I 2 M] [IsManifold I' 2 M'] (f : M → M') (hf : ContMDiff I I' (↑⊤) f) (hp : IsProperMap f) (k : ℕ) (φ : ↥(compactlySupportedForms I' M' k)) :
                          (mextDerivₗ I M k) ((mpullback f hf hp k) φ) = (mpullback f hf hp (k + 1)) ((mextDerivₗ I' M' k) φ)

                          Pullback of compactly supported forms along a smooth proper map commutes with the exterior derivative.

                          theorem TauCeti.SmoothForm.mpullback_mem_exactCompactlySupportedForms {E : Type u_1} {H : Type u_2} {E' : Type u_3} {H' : Type u_4} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] [NormedAddCommGroup E'] [NormedSpace ℝ E'] [TopologicalSpace H'] {I : ModelWithCorners ℝ E H} {I' : ModelWithCorners ℝ E' H'} {M : Type u_7} {M' : Type u_8} [TopologicalSpace M] [ChartedSpace H M] [TopologicalSpace M'] [ChartedSpace H' M'] [IsManifold I 2 M] [IsManifold I' 2 M'] (f : M → M') (hf : ContMDiff I I' (↑⊤) f) (hp : IsProperMap f) {k : ℕ} {φ : SmoothForm I' M' ℝ k} (hφ : φ ∈ exactCompactlySupportedForms I' M' k) :

                          Pullback along a smooth proper map preserves compactly supported exact forms.

                          noncomputable def TauCeti.compactlySupportedClosedForms.mpullback {E : Type u_1} {H : Type u_2} {E' : Type u_3} {H' : Type u_4} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] [NormedAddCommGroup E'] [NormedSpace ℝ E'] [TopologicalSpace H'] {I : ModelWithCorners ℝ E H} {I' : ModelWithCorners ℝ E' H'} {M : Type u_7} {M' : Type u_8} [TopologicalSpace M] [ChartedSpace H M] [TopologicalSpace M'] [ChartedSpace H' M'] [IsManifold I 2 M] [IsManifold I' 2 M'] (f : M → M') (hf : ContMDiff I I' (↑⊤) f) (hp : IsProperMap f) (k : ℕ) :

                          Pullback of compactly supported closed forms along a smooth proper map.

                          Instances For
                            @[simp]
                            theorem TauCeti.compactlySupportedClosedForms.coe_mpullback {E : Type u_1} {H : Type u_2} {E' : Type u_3} {H' : Type u_4} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] [NormedAddCommGroup E'] [NormedSpace ℝ E'] [TopologicalSpace H'] {I : ModelWithCorners ℝ E H} {I' : ModelWithCorners ℝ E' H'} {M : Type u_7} {M' : Type u_8} [TopologicalSpace M] [ChartedSpace H M] [TopologicalSpace M'] [ChartedSpace H' M'] [IsManifold I 2 M] [IsManifold I' 2 M'] (f : M → M') (hf : ContMDiff I I' (↑⊤) f) (hp : IsProperMap f) (k : ℕ) (φ : ↥(compactlySupportedClosedForms I' M' k)) :
                            ↑((mpullback f hf hp k) φ) = (SmoothForm.mpullback f hf) ↑φ

                            The pullback of a compactly supported closed form is its pullback as a smooth form.

                            theorem TauCeti.compactlySupportedClosedForms.coe_coe_mpullback {E : Type u_1} {H : Type u_2} {E' : Type u_3} {H' : Type u_4} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] [NormedAddCommGroup E'] [NormedSpace ℝ E'] [TopologicalSpace H'] {I : ModelWithCorners ℝ E H} {I' : ModelWithCorners ℝ E' H'} {M : Type u_7} {M' : Type u_8} [TopologicalSpace M] [ChartedSpace H M] [TopologicalSpace M'] [ChartedSpace H' M'] [IsManifold I 2 M] [IsManifold I' 2 M'] (f : M → M') (hf : ContMDiff I I' (↑⊤) f) (hp : IsProperMap f) (k : ℕ) (φ : ↥(compactlySupportedClosedForms I' M' k)) :
                            ↑↑((mpullback f hf hp k) φ) = TauCeti.mpullback I I' f ↑↑φ

                            The underlying rough form of the pullback of a compactly supported closed form is the rough pullback of its underlying rough form.

                            @[simp]

                            Pullback of compactly supported closed forms by the identity is the identity linear map.

                            theorem TauCeti.compactlySupportedClosedForms.mpullback_comp {E : Type u_1} {H : Type u_2} {E' : Type u_3} {H' : Type u_4} {E'' : Type u_5} {H'' : Type u_6} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] [NormedAddCommGroup E'] [NormedSpace ℝ E'] [TopologicalSpace H'] [NormedAddCommGroup E''] [NormedSpace ℝ E''] [TopologicalSpace H''] {I : ModelWithCorners ℝ E H} {I' : ModelWithCorners ℝ E' H'} {I'' : ModelWithCorners ℝ E'' H''} {M : Type u_7} {M' : Type u_8} {M'' : Type u_9} [TopologicalSpace M] [ChartedSpace H M] [TopologicalSpace M'] [ChartedSpace H' M'] [TopologicalSpace M''] [ChartedSpace H'' M''] [IsManifold I 2 M] [IsManifold I' 2 M'] [IsManifold I'' 2 M''] (f : M → M') (g : M' → M'') (hf : ContMDiff I I' (↑⊤) f) (hg : ContMDiff I' I'' (↑⊤) g) (hfp : IsProperMap f) (hgp : IsProperMap g) (k : ℕ) :
                            mpullback (g ∘ f) ⋯ ⋯ k = mpullback f hf hfp k ∘ₗ mpullback g hg hgp k

                            Pullback of compactly supported closed forms reverses composition.

                            noncomputable def TauCeti.compactlySupportedDeRhamCohomology.map {E : Type u_1} {H : Type u_2} {E' : Type u_3} {H' : Type u_4} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] [NormedAddCommGroup E'] [NormedSpace ℝ E'] [TopologicalSpace H'] {I : ModelWithCorners ℝ E H} {I' : ModelWithCorners ℝ E' H'} {M : Type u_7} {M' : Type u_8} [TopologicalSpace M] [ChartedSpace H M] [TopologicalSpace M'] [ChartedSpace H' M'] [IsManifold I 2 M] [IsManifold I' 2 M'] (f : M → M') (hf : ContMDiff I I' (↑⊤) f) (hp : IsProperMap f) (k : ℕ) :

                            The contravariant map on compactly supported de Rham cohomology induced by a smooth proper map.

                            Instances For
                              @[simp]
                              theorem TauCeti.compactlySupportedDeRhamCohomology.map_mk {E : Type u_1} {H : Type u_2} {E' : Type u_3} {H' : Type u_4} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] [NormedAddCommGroup E'] [NormedSpace ℝ E'] [TopologicalSpace H'] {I : ModelWithCorners ℝ E H} {I' : ModelWithCorners ℝ E' H'} {M : Type u_7} {M' : Type u_8} [TopologicalSpace M] [ChartedSpace H M] [TopologicalSpace M'] [ChartedSpace H' M'] [IsManifold I 2 M] [IsManifold I' 2 M'] (f : M → M') (hf : ContMDiff I I' (↑⊤) f) (hp : IsProperMap f) (k : ℕ) (φ : ↥(compactlySupportedClosedForms I' M' k)) :
                              (map f hf hp k) ((mk I' k) φ) = (mk I k) ((compactlySupportedClosedForms.mpullback f hf hp k) φ)

                              The induced map sends the class of a compactly supported closed form to the class of its pullback.

                              @[simp]

                              The map on compactly supported cohomology induced by the identity is the identity.

                              theorem TauCeti.compactlySupportedDeRhamCohomology.map_comp {E : Type u_1} {H : Type u_2} {E' : Type u_3} {H' : Type u_4} {E'' : Type u_5} {H'' : Type u_6} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] [NormedAddCommGroup E'] [NormedSpace ℝ E'] [TopologicalSpace H'] [NormedAddCommGroup E''] [NormedSpace ℝ E''] [TopologicalSpace H''] {I : ModelWithCorners ℝ E H} {I' : ModelWithCorners ℝ E' H'} {I'' : ModelWithCorners ℝ E'' H''} {M : Type u_7} {M' : Type u_8} {M'' : Type u_9} [TopologicalSpace M] [ChartedSpace H M] [TopologicalSpace M'] [ChartedSpace H' M'] [TopologicalSpace M''] [ChartedSpace H'' M''] [IsManifold I 2 M] [IsManifold I' 2 M'] [IsManifold I'' 2 M''] (f : M → M') (g : M' → M'') (hf : ContMDiff I I' (↑⊤) f) (hg : ContMDiff I' I'' (↑⊤) g) (hfp : IsProperMap f) (hgp : IsProperMap g) (k : ℕ) :
                              map (g ∘ f) ⋯ ⋯ k = map f hf hfp k ∘ₗ map g hg hgp k

                              Pullback on compactly supported cohomology reverses composition of smooth proper maps.

                              theorem TauCeti.compactlySupportedDeRhamCohomology.toDeRhamCohomology_map {E : Type u_1} {H : Type u_2} {E' : Type u_3} {H' : Type u_4} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] [NormedAddCommGroup E'] [NormedSpace ℝ E'] [TopologicalSpace H'] {I : ModelWithCorners ℝ E H} {I' : ModelWithCorners ℝ E' H'} {M : Type u_7} {M' : Type u_8} [TopologicalSpace M] [ChartedSpace H M] [TopologicalSpace M'] [ChartedSpace H' M'] [IsManifold I 2 M] [IsManifold I' 2 M'] (f : M → M') (hf : ContMDiff I I' (↑⊤) f) (hp : IsProperMap f) (k : ℕ) (c : compactlySupportedDeRhamCohomology I' M' k) :
                              (toDeRhamCohomology I M k) ((map f hf hp k) c) = (deRhamCohomology.map f hf k) ((toDeRhamCohomology I' M' k) c)

                              The comparison with de Rham cohomology commutes with pullback along smooth proper maps.

                              A diffeomorphism Φ : M ≃ M', which is a proper map, induces a linear equivalence H^k_c(M') ≃ H^k_c(M) on compactly supported de Rham cohomology: pullback along Φ, with inverse pullback along Φ.symm.

                              Instances For
                                @[simp]
                                theorem TauCeti.compactlySupportedDeRhamCohomology.equivOfDiffeomorph_apply {E : Type u_1} {H : Type u_2} {E' : Type u_3} {H' : Type u_4} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] [NormedAddCommGroup E'] [NormedSpace ℝ E'] [TopologicalSpace H'] {I : ModelWithCorners ℝ E H} {I' : ModelWithCorners ℝ E' H'} {M : Type u_7} {M' : Type u_8} [TopologicalSpace M] [ChartedSpace H M] [TopologicalSpace M'] [ChartedSpace H' M'] [IsManifold I 2 M] [IsManifold I' 2 M'] (Φ : Diffeomorph I I' M M' ↑⊤) (k : ℕ) (c : compactlySupportedDeRhamCohomology I' M' k) :
                                (equivOfDiffeomorph Φ k) c = (map ⇑Φ ⋯ ⋯ k) c

                                The equivalence induced by a diffeomorphism is pullback along it.

                                @[simp]
                                theorem TauCeti.compactlySupportedDeRhamCohomology.equivOfDiffeomorph_symm_apply {E : Type u_1} {H : Type u_2} {E' : Type u_3} {H' : Type u_4} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] [NormedAddCommGroup E'] [NormedSpace ℝ E'] [TopologicalSpace H'] {I : ModelWithCorners ℝ E H} {I' : ModelWithCorners ℝ E' H'} {M : Type u_7} {M' : Type u_8} [TopologicalSpace M] [ChartedSpace H M] [TopologicalSpace M'] [ChartedSpace H' M'] [IsManifold I 2 M] [IsManifold I' 2 M'] (Φ : Diffeomorph I I' M M' ↑⊤) (k : ℕ) (c : compactlySupportedDeRhamCohomology I M k) :
                                (equivOfDiffeomorph Φ k).symm c = (map ⇑Φ.symm ⋯ ⋯ k) c

                                The inverse of the equivalence induced by a diffeomorphism is pullback along its inverse.

                                theorem TauCeti.compactlySupportedDeRhamCohomology.equivOfDiffeomorph_mk {E : Type u_1} {H : Type u_2} {E' : Type u_3} {H' : Type u_4} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] [NormedAddCommGroup E'] [NormedSpace ℝ E'] [TopologicalSpace H'] {I : ModelWithCorners ℝ E H} {I' : ModelWithCorners ℝ E' H'} {M : Type u_7} {M' : Type u_8} [TopologicalSpace M] [ChartedSpace H M] [TopologicalSpace M'] [ChartedSpace H' M'] [IsManifold I 2 M] [IsManifold I' 2 M'] (Φ : Diffeomorph I I' M M' ↑⊤) (k : ℕ) (φ : ↥(compactlySupportedClosedForms I' M' k)) :
                                (equivOfDiffeomorph Φ k) ((mk I' k) φ) = (mk I k) ((compactlySupportedClosedForms.mpullback ⇑Φ ⋯ ⋯ k) φ)

                                The equivalence induced by a diffeomorphism sends the class of a compactly supported closed form to the class of its pullback.

                                The induced cochain maps compare complexes in one universe, so the model spaces share a universe, as do the manifolds.

                                The cochain map between compactly supported de Rham complexes induced by a smooth proper map.

                                Instances For

                                  Under the canonical identifications of the objects, the induced cochain map is pullback of compactly supported forms.

                                  Under the canonical identifications of the objects, the induced cochain map is pullback of compactly supported forms.

                                  @[simp]

                                  The cochain map induced by the identity is the identity.

                                  theorem TauCeti.compactlySupportedDeRhamComplex.map_comp {E E' E'' : Type u} {H : Type u_1} {H' : Type u_2} {H'' : Type u_3} [NormedAddCommGroup E] [NormedSpace ℝ E] [TopologicalSpace H] [NormedAddCommGroup E'] [NormedSpace ℝ E'] [TopologicalSpace H'] [NormedAddCommGroup E''] [NormedSpace ℝ E''] [TopologicalSpace H''] {I : ModelWithCorners ℝ E H} {I' : ModelWithCorners ℝ E' H'} {I'' : ModelWithCorners ℝ E'' H''} {M M' M'' : Type v} [TopologicalSpace M] [ChartedSpace H M] [IsManifold I 2 M] [TopologicalSpace M'] [ChartedSpace H' M'] [IsManifold I' 2 M'] [TopologicalSpace M''] [ChartedSpace H'' M''] [IsManifold I'' 2 M''] (f : M → M') (g : M' → M'') (hf : ContMDiff I I' (↑⊤) f) (hg : ContMDiff I' I'' (↑⊤) g) (hfp : IsProperMap f) (hgp : IsProperMap g) :
                                  map (g ∘ f) ⋯ ⋯ = CategoryTheory.CategoryStruct.comp (map g hg hgp) (map f hf hfp)

                                  The induced cochain maps reverse composition of smooth proper maps.

                                  The map induced on cohomology by the cochain map of a smooth proper map is pullback on compactly supported cohomology.