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Mathlib.CategoryTheory.Bicategory.Yoneda

2-Yoneda embedding #

In this file we define the bicategorical Yoneda embedding.

def CategoryTheory.Bicategory.precomposingCat {B : Type u} [Bicategory B] (a b c : B) :
Functor (a b) (Cat.of (b c) Cat.of (a c))

Version of Bicategory.precomposing viewed in the bicategory Cat.

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    theorem CategoryTheory.Bicategory.precomposingCat_obj {B : Type u} [Bicategory B] (a b c : B) (f : a b) :
    @[simp]
    theorem CategoryTheory.Bicategory.precomposingCat_map {B : Type u} [Bicategory B] (a b c : B) {X✝ Y✝ : a b} (η : X✝ Y✝) :
    def CategoryTheory.Bicategory.postcomposingCat {B : Type u} [Bicategory B] (a b c : B) :
    Functor (b c) (Cat.of (a b) Cat.of (a c))

    Version of Bicategory.postcomposing viewed in the bicategory Cat.

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      theorem CategoryTheory.Bicategory.postcomposingCat_map {B : Type u} [Bicategory B] (a b c : B) {X✝ Y✝ : b c} (η : X✝ Y✝) :
      @[simp]
      theorem CategoryTheory.Bicategory.postcomposingCat_obj {B : Type u} [Bicategory B] (a b c : B) (f : b c) :

      Right component of the associator as a 2-isomorphism in Cat.

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        theorem CategoryTheory.Bicategory.associatorNatIsoRightCat_hom_toNatTrans_app {B : Type u} [Bicategory B] {a b c : B} (f : a b) (g : b c) (d : B) (X : c d) :
        @[simp]
        theorem CategoryTheory.Bicategory.associatorNatIsoRightCat_inv_toNatTrans_app {B : Type u} [Bicategory B] {a b c : B} (f : a b) (g : b c) (d : B) (X : c d) :

        Middle component of the associator as a 2-isomorphism in Cat.

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          @[simp]

          Left component of the associator as a 2-isomorphism in Cat.

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            theorem CategoryTheory.Bicategory.associatorNatIsoLeftCat_hom_toNatTrans_app {B : Type u} [Bicategory B] (a : B) {b c d : B} (g : b c) (h : c d) (X : (Cat.of (a b))) :
            @[simp]
            theorem CategoryTheory.Bicategory.associatorNatIsoLeftCat_inv_toNatTrans_app {B : Type u} [Bicategory B] (a : B) {b c d : B} (g : b c) (h : c d) (X : (Cat.of (a b))) :

            The map on objects underlying the Yoneda embedding. It sends an object x to the pseudofunctor defined by:

            • Objects: a ↦ (a ⟶ x)
            • Higher morphisms get sent to the corresponding "precomposing" operation.

            This is only used for defining yoneda, after which Bicategory.yoneda.obj should be prefered.

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              theorem CategoryTheory.Bicategory.yoneda₀_mapComp_inv_toNatTrans_app {B : Type u} [Bicategory B] (x : B) {a✝ b✝ c✝ : Bᵒᵖ} (f : a✝ b✝) (g : b✝ c✝) (X : Opposite.unop a✝ x) :
              @[simp]
              theorem CategoryTheory.Bicategory.yoneda₀_mapComp_hom_toNatTrans_app {B : Type u} [Bicategory B] (x : B) {a✝ b✝ c✝ : Bᵒᵖ} (f : a✝ b✝) (g : b✝ c✝) (X : Opposite.unop a✝ x) :
              @[simp]
              theorem CategoryTheory.Bicategory.yoneda₀_toPrelaxFunctor_toPrelaxFunctorStruct_map₂_toNatTrans_app {B : Type u} [Bicategory B] (x : B) {a b : Bᵒᵖ} {f✝ g✝ : a b} (a✝ : f✝ g✝) (x✝ : Opposite.unop a x) :
              ((yoneda₀ x).map₂ a✝).toNatTrans.app x✝ = whiskerRight a✝.unop2 x✝
              @[simp]
              theorem CategoryTheory.Bicategory.yoneda₀_toPrelaxFunctor_toPrelaxFunctorStruct_toPrefunctor_map_toFunctor_map {B : Type u} [Bicategory B] (x : B) {a b : Bᵒᵖ} (a✝ : a b) {X✝ Y✝ : Opposite.unop a x} (x✝ : X✝ Y✝) :
              ((yoneda₀ x).map a✝).toFunctor.map x✝ = whiskerLeft a✝.unop x✝

              Postcomposing of a 1-morphism seen as a strong transformation between pseudofunctors.

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                theorem CategoryTheory.Bicategory.postcomp₂_app_toFunctor_map {B : Type u} [Bicategory B] {a b : B} (f : a b) (x : Bᵒᵖ) {X✝ Y✝ : Opposite.unop x a} (x✝ : X✝ Y✝) :
                @[simp]
                theorem CategoryTheory.Bicategory.postcomp₂_naturality_hom_toNatTrans_app {B : Type u} [Bicategory B] {a b : B} (f : a b) {a✝ b✝ : Bᵒᵖ} (g : a✝ b✝) (X : (Cat.of (Opposite.unop a✝ a))) :
                @[simp]
                theorem CategoryTheory.Bicategory.postcomp₂_naturality_inv_toNatTrans_app {B : Type u} [Bicategory B] {a b : B} (f : a b) {a✝ b✝ : Bᵒᵖ} (g : a✝ b✝) (X : (Cat.of (Opposite.unop a✝ a))) :
                @[simp]

                Postcomposing of 1-morphisms seen as a functor from a ⟶ b to the hom-category of the corresponding pseudofunctors.

                This is an implementation detail, and Bicategory.yoneda.map should be prefered.

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                  theorem CategoryTheory.Bicategory.postcomposing₂_obj_naturality_hom_toNatTrans_app {B : Type u} [Bicategory B] (a b : B) (f : a b) {a✝ b✝ : Bᵒᵖ} (g : a✝ b✝) (X : (Cat.of (Opposite.unop a✝ a))) :
                  @[simp]
                  theorem CategoryTheory.Bicategory.postcomposing₂_map_as_app_toNatTrans_app {B : Type u} [Bicategory B] (a b : B) {X✝ Y✝ : a b} (η : X✝ Y✝) (x : Bᵒᵖ) (x✝ : Opposite.unop x a) :
                  (((postcomposing₂ a b).map η).as.app x).toNatTrans.app x✝ = whiskerLeft x✝ η
                  @[simp]
                  theorem CategoryTheory.Bicategory.postcomposing₂_obj_naturality_inv_toNatTrans_app {B : Type u} [Bicategory B] (a b : B) (f : a b) {a✝ b✝ : Bᵒᵖ} (g : a✝ b✝) (X : (Cat.of (Opposite.unop a✝ a))) :
                  @[simp]
                  theorem CategoryTheory.Bicategory.postcomposing₂_obj_app_toFunctor_map {B : Type u} [Bicategory B] (a b : B) (f : a b) (x : Bᵒᵖ) {X✝ Y✝ : Opposite.unop x a} (x✝ : X✝ Y✝) :
                  (((postcomposing₂ a b).obj f).app x).toFunctor.map x✝ = whiskerRight x✝ f

                  The Yoneda pseudofunctor from B to Bᵒᵖ ⥤ᵖ Cat.

                  It consists of the following:

                  • On objects: sends x : B to the pseudofunctor Bᵒᵖ ⥤ᵖ Cat given by a ↦ (a ⟶ x) on objects and on 1- and 2-morphisms given by "precomposing"
                  • On 1- and 2-morphisms it is given by "postcomposing"
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                    theorem CategoryTheory.Bicategory.yoneda_toPrelaxFunctor_toPrelaxFunctorStruct_map₂_as_app_toNatTrans_app {B : Type u} [Bicategory B] {a b : B} {f✝ g✝ : a b} (a✝ : f✝ g✝) (x : Bᵒᵖ) (x✝ : Opposite.unop x a) :
                    ((yoneda.map₂ a✝).as.app x).toNatTrans.app x✝ = whiskerLeft x✝ a✝
                    @[simp]
                    theorem CategoryTheory.Bicategory.yoneda_toPrelaxFunctor_toPrelaxFunctorStruct_toPrefunctor_obj_mapComp_inv_toNatTrans_app {B : Type u} [Bicategory B] (x✝ : B) {a✝ b✝ c✝ : Bᵒᵖ} (f : a✝ b✝) (g : b✝ c✝) (X : Opposite.unop a✝ x✝) :
                    @[simp]
                    theorem CategoryTheory.Bicategory.yoneda_toPrelaxFunctor_toPrelaxFunctorStruct_toPrefunctor_map_app_toFunctor_map {B : Type u} [Bicategory B] {a b : B} (a✝ : a b) (x : Bᵒᵖ) {X✝ Y✝ : Opposite.unop x a} (x✝ : X✝ Y✝) :
                    ((yoneda.map a✝).app x).toFunctor.map x✝ = whiskerRight x✝ a✝
                    @[simp]
                    @[simp]
                    theorem CategoryTheory.Bicategory.yoneda_toPrelaxFunctor_toPrelaxFunctorStruct_toPrefunctor_obj_mapComp_hom_toNatTrans_app {B : Type u} [Bicategory B] (x✝ : B) {a✝ b✝ c✝ : Bᵒᵖ} (f : a✝ b✝) (g : b✝ c✝) (X : Opposite.unop a✝ x✝) :
                    @[simp]
                    theorem CategoryTheory.Bicategory.yoneda_mapComp_inv_as_app_toNatTrans_app {B : Type u} [Bicategory B] {a✝ b✝ c✝ : B} (f : a✝ b✝) (g : b✝ c✝) (a : Bᵒᵖ) (X : (Cat.of (Opposite.unop a a✝))) :
                    @[simp]
                    @[simp]
                    theorem CategoryTheory.Bicategory.yoneda_mapComp_hom_as_app_toNatTrans_app {B : Type u} [Bicategory B] {a✝ b✝ c✝ : B} (f : a✝ b✝) (g : b✝ c✝) (a : Bᵒᵖ) (X : (Cat.of (Opposite.unop a a✝))) :