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Mathlib.CategoryTheory.Bicategory.NaturalTransformation.Oplax

Oplax transformations between oplax functors #

Just as there are natural transformations between functors, there are oplax transformations between oplax functors. The equality in the naturality of natural transformations is replaced by a specified 2-morphism F.map f ≫ app b ⟶ app a ≫ G.map f in the case of oplax natural transformations.

Main definitions #

Using this, we define a category instance on OplaxTrans F G, with composition given by vertical composition of oplax transformations.

TODO #

This file could also include lax and strong transformations between oplax functors.

structure CategoryTheory.Oplax.OplaxTrans {B : Type u₁} [Bicategory B] {C : Type u₂} [Bicategory C] (F G : OplaxFunctor B C) :
Type (max (max (max u₁ v₁) v₂) w₂)

If η is an oplax transformation between F and G, we have a 1-morphism η.app a : F.obj a ⟶ G.obj a for each object a : B. We also have a 2-morphism η.naturality f : F.map f ≫ app b ⟶ app a ≫ G.map f for each 1-morphism f : a ⟶ b. These 2-morphisms satisfies the naturality condition, and preserve the identities and the compositions modulo some adjustments of domains and codomains of 2-morphisms.

Instances For
    @[simp]
    theorem CategoryTheory.Oplax.OplaxTrans.naturality_naturality_assoc {B : Type u₁} [Bicategory B] {C : Type u₂} [Bicategory C] {F G : OplaxFunctor B C} (self : OplaxTrans F G) {a b : B} {f g : a b} (η : f g) {Z : F.obj a G.obj b} (h : CategoryStruct.comp (self.app a) (G.map g) Z) :
    @[deprecated CategoryTheory.Oplax.OplaxTrans (since := "2025-04-23")]
    def CategoryTheory.OplaxNatTrans {B : Type u₁} [Bicategory B] {C : Type u₂} [Bicategory C] (F G : OplaxFunctor B C) :
    Type (max (max (max u₁ v₁) v₂) w₂)

    Alias of CategoryTheory.Oplax.OplaxTrans.


    If η is an oplax transformation between F and G, we have a 1-morphism η.app a : F.obj a ⟶ G.obj a for each object a : B. We also have a 2-morphism η.naturality f : F.map f ≫ app b ⟶ app a ≫ G.map f for each 1-morphism f : a ⟶ b. These 2-morphisms satisfies the naturality condition, and preserve the identities and the compositions modulo some adjustments of domains and codomains of 2-morphisms.

    Equations
    Instances For
      @[simp]
      theorem CategoryTheory.Oplax.OplaxTrans.whiskerRight_naturality_comp_assoc {B : Type u₁} [Bicategory B] {C : Type u₂} [Bicategory C] {F G : OplaxFunctor B C} (η : OplaxTrans F G) {a b c : B} {a' : C} (f : a b) (g : b c) (h : G.obj c a') {Z : F.obj a a'} (h✝ : CategoryStruct.comp (η.app a) (CategoryStruct.comp (CategoryStruct.comp (G.map f) (G.map g)) h) Z) :

      The identity oplax transformation.

      Equations
      • One or more equations did not get rendered due to their size.
      Instances For
        def CategoryTheory.Oplax.OplaxTrans.vcomp {B : Type u₁} [Bicategory B] {C : Type u₂} [Bicategory C] {F G H : OplaxFunctor B C} (η : OplaxTrans F G) (θ : OplaxTrans G H) :

        Vertical composition of oplax transformations.

        Equations
        • One or more equations did not get rendered due to their size.
        Instances For
          @[simp]
          @[simp]
          theorem CategoryTheory.Oplax.OplaxTrans.instCategoryStructOplaxFunctor_comp_app {B : Type u₁} [Bicategory B] {C : Type u₂} [Bicategory C] {X✝ Y✝ Z✝ : OplaxFunctor B C} (η : OplaxTrans X✝ Y✝) (θ : OplaxTrans Y✝ Z✝) (a : B) :