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Mathlib.Algebra.Homology.Embedding.Restriction

The restriction functor of an embedding of complex shapes #

Given c and c' complex shapes on two types, and e : c.Embedding c' (satisfying [e.IsRelIff]), we define the restriction functor e.restrictionFunctor C : HomologicalComplex C c' ⥤ HomologicalComplex C c.

Given K : HomologicalComplex C c' and e : c.Embedding c' (satisfying [e.IsRelIff]), this is the homological complex in HomologicalComplex C c obtained by restriction.

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      @[simp]
      theorem HomologicalComplex.restriction_d {ι : Type u_1} {ι' : Type u_2} {c : ComplexShape ι} {c' : ComplexShape ι'} {C : Type u_3} [CategoryTheory.Category.{u_4, u_3} C] [CategoryTheory.Limits.HasZeroMorphisms C] (K : HomologicalComplex C c') (e : c.Embedding c') [e.IsRelIff] (x✝ x✝¹ : ι) :
      (K.restriction e).d x✝ x✝¹ = K.d (e.f x✝) (e.f x✝¹)
      @[simp]
      theorem HomologicalComplex.restriction_X {ι : Type u_1} {ι' : Type u_2} {c : ComplexShape ι} {c' : ComplexShape ι'} {C : Type u_3} [CategoryTheory.Category.{u_4, u_3} C] [CategoryTheory.Limits.HasZeroMorphisms C] (K : HomologicalComplex C c') (e : c.Embedding c') [e.IsRelIff] (i : ι) :
      (K.restriction e).X i = K.X (e.f i)
      def HomologicalComplex.restrictionXIso {ι : Type u_1} {ι' : Type u_2} {c : ComplexShape ι} {c' : ComplexShape ι'} {C : Type u_3} [CategoryTheory.Category.{u_4, u_3} C] [CategoryTheory.Limits.HasZeroMorphisms C] (K : HomologicalComplex C c') (e : c.Embedding c') [e.IsRelIff] {i : ι} {i' : ι'} (h : e.f i = i') :
      (K.restriction e).X i K.X i'

      The isomorphism (K.restriction e).X i ≅ K.X i' when e.f i = i'.

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          theorem HomologicalComplex.restriction_d_eq {ι : Type u_1} {ι' : Type u_2} {c : ComplexShape ι} {c' : ComplexShape ι'} {C : Type u_3} [CategoryTheory.Category.{u_4, u_3} C] [CategoryTheory.Limits.HasZeroMorphisms C] (K : HomologicalComplex C c') (e : c.Embedding c') [e.IsRelIff] {i j : ι} {i' j' : ι'} (hi : e.f i = i') (hj : e.f j = j') :

          The morphism K.restriction e ⟶ L.restriction e induced by a morphism φ : K ⟶ L.

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              @[simp]
              theorem HomologicalComplex.restrictionMap_f {ι : Type u_1} {ι' : Type u_2} {c : ComplexShape ι} {c' : ComplexShape ι'} {C : Type u_3} [CategoryTheory.Category.{u_4, u_3} C] [CategoryTheory.Limits.HasZeroMorphisms C] {K L : HomologicalComplex C c'} (φ : K L) (e : c.Embedding c') [e.IsRelIff] (i : ι) :
              (restrictionMap φ e).f i = φ.f (e.f i)

              Given e : ComplexShape.Embedding c c', this is the restriction functor HomologicalComplex C c' ⥤ HomologicalComplex C c.

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