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Mathlib.CategoryTheory.GuitartExact.HorizontalComposition

Horizontal composition of Guitart exact squares #

In this file, we show that the horizontal composition of Guitart exact squares is Guitart exact.

def CategoryTheory.TwoSquare.whiskerHorizontal {C₁ : Type u_1} {C₂ : Type u_2} {D₁ : Type u_4} {D₂ : Type u_5} [Category.{v_1, u_1} C₁] [Category.{v_2, u_2} C₂] [Category.{v_4, u_4} D₁] [Category.{v_5, u_5} D₂] {T : Functor C₁ D₁} {L : Functor C₁ C₂} {R : Functor D₁ D₂} {B : Functor C₂ D₂} (w : TwoSquare T L R B) {T' : Functor C₁ D₁} {B' : Functor C₂ D₂} (α : T' T) (β : B B') :
TwoSquare T' L R B'

Given w : TwoSquare T L R B, one may obtain a 2-square TwoSquare T' L R B' if we provide natural transformations α : T ⟶ T' and β : B' ⟶ B.

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    @[simp]
    theorem CategoryTheory.TwoSquare.whiskerHorizontal_app {C₁ : Type u_1} {C₂ : Type u_2} {D₁ : Type u_4} {D₂ : Type u_5} [Category.{v_1, u_1} C₁] [Category.{v_2, u_2} C₂] [Category.{v_4, u_4} D₁] [Category.{v_5, u_5} D₂] {T : Functor C₁ D₁} {L : Functor C₁ C₂} {R : Functor D₁ D₂} {B : Functor C₂ D₂} (w : TwoSquare T L R B) {T' : Functor C₁ D₁} {B' : Functor C₂ D₂} (α : T' T) (β : B B') (X : C₁) :
    theorem CategoryTheory.TwoSquare.GuitartExact.whiskerHorizontal {C₁ : Type u_1} {C₂ : Type u_2} {D₁ : Type u_4} {D₂ : Type u_5} [Category.{v_1, u_1} C₁] [Category.{v_2, u_2} C₂] [Category.{v_4, u_4} D₁] [Category.{v_5, u_5} D₂] {T : Functor C₁ D₁} {L : Functor C₁ C₂} {R : Functor D₁ D₂} {B : Functor C₂ D₂} (w : TwoSquare T L R B) {T' : Functor C₁ D₁} {B' : Functor C₂ D₂} [w.GuitartExact] (α : T T') (β : B B') :

    A 2-square stays Guitart exact if we replace the top and bottom functors by isomorphic functors. See also whiskerHorizontal_iff.

    @[simp]
    theorem CategoryTheory.TwoSquare.GuitartExact.whiskerHorizontal_iff {C₁ : Type u_1} {C₂ : Type u_2} {D₁ : Type u_4} {D₂ : Type u_5} [Category.{v_1, u_1} C₁] [Category.{v_2, u_2} C₂] [Category.{v_4, u_4} D₁] [Category.{v_5, u_5} D₂] {T : Functor C₁ D₁} {L : Functor C₁ C₂} {R : Functor D₁ D₂} {B : Functor C₂ D₂} (w : TwoSquare T L R B) {T' : Functor C₁ D₁} {B' : Functor C₂ D₂} (α : T T') (β : B B') :

    A 2-square is Guitart exact iff it is so after replacing the top and bottom functors by isomorphic functors.

    instance CategoryTheory.TwoSquare.GuitartExact.instWhiskerHorizontalOfIsIsoFunctor {C₁ : Type u_1} {C₂ : Type u_2} {D₁ : Type u_4} {D₂ : Type u_5} [Category.{v_1, u_1} C₁] [Category.{v_2, u_2} C₂] [Category.{v_4, u_4} D₁] [Category.{v_5, u_5} D₂] {T : Functor C₁ D₁} {L : Functor C₁ C₂} {R : Functor D₁ D₂} {B : Functor C₂ D₂} (w : TwoSquare T L R B) {T' : Functor C₁ D₁} {B' : Functor C₂ D₂} [w.GuitartExact] (α : T' T) (β : B B') [IsIso α] [IsIso β] :
    def CategoryTheory.TwoSquare.hComp' {C₁ : Type u_1} {C₂ : Type u_2} {C₃ : Type u_3} {D₁ : Type u_4} {D₂ : Type u_5} {D₃ : Type u_6} [Category.{v_1, u_1} C₁] [Category.{v_2, u_2} C₂] [Category.{v_3, u_3} C₃] [Category.{v_4, u_4} D₁] [Category.{v_5, u_5} D₂] [Category.{v_6, u_6} D₃] {V₁ : Functor C₁ D₁} {T₁ : Functor C₁ C₂} {B₁ : Functor D₁ D₂} {V₂ : Functor C₂ D₂} (w : TwoSquare T₁ V₁ V₂ B₁) {T₂ : Functor C₂ C₃} {B₂ : Functor D₂ D₃} {V₃ : Functor C₃ D₃} (w' : TwoSquare T₂ V₂ V₃ B₂) {T₁₂ : Functor C₁ C₃} {B₁₂ : Functor D₁ D₃} (eT : T₁.comp T₂ T₁₂) (eB : B₁.comp B₂ B₁₂) :
    TwoSquare T₁₂ V₁ V₃ B₁₂

    The horizontal composition of 2-squares. (Variant where we allow the replacement of the horizontal compositions by isomorphic functors.)

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      @[simp]
      theorem CategoryTheory.TwoSquare.hComp'_app {C₁ : Type u_1} {C₂ : Type u_2} {C₃ : Type u_3} {D₁ : Type u_4} {D₂ : Type u_5} {D₃ : Type u_6} [Category.{v_1, u_1} C₁] [Category.{v_2, u_2} C₂] [Category.{v_3, u_3} C₃] [Category.{v_4, u_4} D₁] [Category.{v_5, u_5} D₂] [Category.{v_6, u_6} D₃] {V₁ : Functor C₁ D₁} {T₁ : Functor C₁ C₂} {B₁ : Functor D₁ D₂} {V₂ : Functor C₂ D₂} (w : TwoSquare T₁ V₁ V₂ B₁) {T₂ : Functor C₂ C₃} {B₂ : Functor D₂ D₃} {V₃ : Functor C₃ D₃} (w' : TwoSquare T₂ V₂ V₃ B₂) {T₁₂ : Functor C₁ C₃} {B₁₂ : Functor D₁ D₃} (eT : T₁.comp T₂ T₁₂) (eB : B₁.comp B₂ B₁₂) (X : C₁) :
      (w.hComp' w' eT eB).app X = CategoryStruct.comp (V₃.map (eT.inv.app X)) (CategoryStruct.comp (w'.natTrans.app (T₁.obj X)) (CategoryStruct.comp (B₂.map (w.natTrans.app X)) (eB.hom.app (V₁.obj X))))
      instance CategoryTheory.TwoSquare.GuitartExact.hComp {C₁ : Type u_1} {C₂ : Type u_2} {C₃ : Type u_3} {D₁ : Type u_4} {D₂ : Type u_5} {D₃ : Type u_6} [Category.{v_1, u_1} C₁] [Category.{v_2, u_2} C₂] [Category.{v_3, u_3} C₃] [Category.{v_4, u_4} D₁] [Category.{v_5, u_5} D₂] [Category.{v_6, u_6} D₃] {V₁ : Functor C₁ D₁} {T₁ : Functor C₁ C₂} {B₁ : Functor D₁ D₂} {V₂ : Functor C₂ D₂} (w : TwoSquare T₁ V₁ V₂ B₁) {T₂ : Functor C₂ C₃} {B₂ : Functor D₂ D₃} {V₃ : Functor C₃ D₃} (w' : TwoSquare T₂ V₂ V₃ B₂) [w.GuitartExact] [w'.GuitartExact] :
      instance CategoryTheory.TwoSquare.GuitartExact.hComp' {C₁ : Type u_1} {C₂ : Type u_2} {C₃ : Type u_3} {D₁ : Type u_4} {D₂ : Type u_5} {D₃ : Type u_6} [Category.{v_1, u_1} C₁] [Category.{v_2, u_2} C₂] [Category.{v_3, u_3} C₃] [Category.{v_4, u_4} D₁] [Category.{v_5, u_5} D₂] [Category.{v_6, u_6} D₃] {V₁ : Functor C₁ D₁} {T₁ : Functor C₁ C₂} {B₁ : Functor D₁ D₂} {V₂ : Functor C₂ D₂} (w : TwoSquare T₁ V₁ V₂ B₁) {T₂ : Functor C₂ C₃} {B₂ : Functor D₂ D₃} {V₃ : Functor C₃ D₃} (w' : TwoSquare T₂ V₂ V₃ B₂) {T₁₂ : Functor C₁ C₃} {B₁₂ : Functor D₁ D₃} (eT : T₁.comp T₂ T₁₂) (eB : B₁.comp B₂ B₁₂) [w.GuitartExact] [w'.GuitartExact] :
      (w.hComp' w' eT eB).GuitartExact
      def CategoryTheory.TwoSquare.GuitartExact.costructuredArrowRightwardsComp {C₁ : Type u_1} {C₂ : Type u_2} {C₃ : Type u_3} {D₁ : Type u_4} {D₂ : Type u_5} {D₃ : Type u_6} [Category.{v_1, u_1} C₁] [Category.{v_2, u_2} C₂] [Category.{v_3, u_3} C₃] [Category.{v_4, u_4} D₁] [Category.{v_5, u_5} D₂] [Category.{v_6, u_6} D₃] {V₁ : Functor C₁ D₁} {T₁ : Functor C₁ C₂} {B₁ : Functor D₁ D₂} {V₂ : Functor C₂ D₂} (w : TwoSquare T₁ V₁ V₂ B₁) {T₂ : Functor C₂ C₃} {B₂ : Functor D₂ D₃} {V₃ : Functor C₃ D₃} (w' : TwoSquare T₂ V₂ V₃ B₂) (Y₁ : D₁) :

      The canonical isomorphism between w.costructuredArrowRightwards Y₁ ⋙ w'.costructuredArrowRightwards (B₁.obj Y₁) and (w ≫ₕ w').costructuredArrowRightwards Y₁.

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        theorem CategoryTheory.TwoSquare.GuitartExact.of_hComp {C₁ : Type u_1} {C₂ : Type u_2} {C₃ : Type u_3} {D₁ : Type u_4} {D₂ : Type u_5} {D₃ : Type u_6} [Category.{v_1, u_1} C₁] [Category.{v_2, u_2} C₂] [Category.{v_3, u_3} C₃] [Category.{v_4, u_4} D₁] [Category.{v_5, u_5} D₂] [Category.{v_6, u_6} D₃] {V₁ : Functor C₁ D₁} {T₁ : Functor C₁ C₂} {B₁ : Functor D₁ D₂} {V₂ : Functor C₂ D₂} (w : TwoSquare T₁ V₁ V₂ B₁) {T₂ : Functor C₂ C₃} {B₂ : Functor D₂ D₃} {V₃ : Functor C₃ D₃} (w' : TwoSquare T₂ V₂ V₃ B₂) [B₁.EssSurj] [w.GuitartExact] [(w.hComp w').GuitartExact] :
        theorem CategoryTheory.TwoSquare.GuitartExact.of_hComp' {C₁ : Type u_1} {C₂ : Type u_2} {C₃ : Type u_3} {D₁ : Type u_4} {D₂ : Type u_5} {D₃ : Type u_6} [Category.{v_1, u_1} C₁] [Category.{v_2, u_2} C₂] [Category.{v_3, u_3} C₃] [Category.{v_4, u_4} D₁] [Category.{v_5, u_5} D₂] [Category.{v_6, u_6} D₃] {V₁ : Functor C₁ D₁} {T₁ : Functor C₁ C₂} {B₁ : Functor D₁ D₂} {V₂ : Functor C₂ D₂} (w : TwoSquare T₁ V₁ V₂ B₁) {T₂ : Functor C₂ C₃} {B₂ : Functor D₂ D₃} {V₃ : Functor C₃ D₃} (w' : TwoSquare T₂ V₂ V₃ B₂) {T₁₂ : Functor C₁ C₃} {B₁₂ : Functor D₁ D₃} (eT : T₁.comp T₂ T₁₂) (eB : B₁.comp B₂ B₁₂) [B₁.EssSurj] [w.GuitartExact] [h : (w.hComp' w' eT eB).GuitartExact] :
        theorem CategoryTheory.TwoSquare.GuitartExact.hComp_iff_of_essSurj {C₁ : Type u_1} {C₂ : Type u_2} {C₃ : Type u_3} {D₁ : Type u_4} {D₂ : Type u_5} {D₃ : Type u_6} [Category.{v_1, u_1} C₁] [Category.{v_2, u_2} C₂] [Category.{v_3, u_3} C₃] [Category.{v_4, u_4} D₁] [Category.{v_5, u_5} D₂] [Category.{v_6, u_6} D₃] {V₁ : Functor C₁ D₁} {T₁ : Functor C₁ C₂} {B₁ : Functor D₁ D₂} {V₂ : Functor C₂ D₂} (w : TwoSquare T₁ V₁ V₂ B₁) {T₂ : Functor C₂ C₃} {B₂ : Functor D₂ D₃} {V₃ : Functor C₃ D₃} (w' : TwoSquare T₂ V₂ V₃ B₂) [B₁.EssSurj] [w.GuitartExact] :
        theorem CategoryTheory.TwoSquare.GuitartExact.hComp'_iff_of_essSurj {C₁ : Type u_1} {C₂ : Type u_2} {C₃ : Type u_3} {D₁ : Type u_4} {D₂ : Type u_5} {D₃ : Type u_6} [Category.{v_1, u_1} C₁] [Category.{v_2, u_2} C₂] [Category.{v_3, u_3} C₃] [Category.{v_4, u_4} D₁] [Category.{v_5, u_5} D₂] [Category.{v_6, u_6} D₃] {V₁ : Functor C₁ D₁} {T₁ : Functor C₁ C₂} {B₁ : Functor D₁ D₂} {V₂ : Functor C₂ D₂} (w : TwoSquare T₁ V₁ V₂ B₁) {T₂ : Functor C₂ C₃} {B₂ : Functor D₂ D₃} {V₃ : Functor C₃ D₃} (w' : TwoSquare T₂ V₂ V₃ B₂) {T₁₂ : Functor C₁ C₃} {B₁₂ : Functor D₁ D₃} (eT : T₁.comp T₂ T₁₂) (eB : B₁.comp B₂ B₁₂) [B₁.EssSurj] [w.GuitartExact] :
        theorem CategoryTheory.TwoSquare.GuitartExact.hComp_iff_of_equivalences {C₁ : Type u_1} {C₂ : Type u_2} {C₃ : Type u_3} {D₁ : Type u_4} {D₂ : Type u_5} {D₃ : Type u_6} [Category.{v_1, u_1} C₁] [Category.{v_2, u_2} C₂] [Category.{v_3, u_3} C₃] [Category.{v_4, u_4} D₁] [Category.{v_5, u_5} D₂] [Category.{v_6, u_6} D₃] {V₁ : Functor C₁ D₁} {T₁ : Functor C₁ C₂} {B₁ : Functor D₁ D₂} {V₂ : Functor C₂ D₂} (w : TwoSquare T₁ V₁ V₂ B₁) {V₃ : Functor C₃ D₃} (eT : C₂ C₃) (eB : D₂ D₃) (w' : eT.functor.comp V₃ V₂.comp eB.functor) :
        theorem CategoryTheory.TwoSquare.GuitartExact.hComp'_iff_of_equivalences {C₁ : Type u_1} {C₂ : Type u_2} {C₃ : Type u_3} {D₁ : Type u_4} {D₂ : Type u_5} {D₃ : Type u_6} [Category.{v_1, u_1} C₁] [Category.{v_2, u_2} C₂] [Category.{v_3, u_3} C₃] [Category.{v_4, u_4} D₁] [Category.{v_5, u_5} D₂] [Category.{v_6, u_6} D₃] {V₁ : Functor C₁ D₁} {T₁ : Functor C₁ C₂} {B₁ : Functor D₁ D₂} {V₂ : Functor C₂ D₂} (w : TwoSquare T₁ V₁ V₂ B₁) {V₃ : Functor C₃ D₃} (E : C₂ C₃) (E' : D₂ D₃) (w' : E.functor.comp V₃ V₂.comp E'.functor) {T₁₂ : Functor C₁ C₃} {B₁₂ : Functor D₁ D₃} (eT : T₁.comp E.functor T₁₂) (eB : B₁.comp E'.functor B₁₂) :