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 #
OplaxTrans F G
: oplax transformations between oplax functorsF
andG
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.
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.
The component 1-morphisms of an oplax transformation.
- naturality {a b : B} (f : a ⟶ b) : CategoryStruct.comp (F.map f) (self.app b) ⟶ CategoryStruct.comp (self.app a) (G.map f)
The 2-morphisms underlying the oplax naturality constraint.
- naturality_naturality {a b : B} {f g : a ⟶ b} (η : f ⟶ g) : CategoryStruct.comp (Bicategory.whiskerRight (F.map₂ η) (self.app b)) (self.naturality g) = CategoryStruct.comp (self.naturality f) (Bicategory.whiskerLeft (self.app a) (G.map₂ η))
Naturality of the oplax naturality constraint.
- naturality_id (a : B) : CategoryStruct.comp (self.naturality (CategoryStruct.id a)) (Bicategory.whiskerLeft (self.app a) (G.mapId a)) = CategoryStruct.comp (Bicategory.whiskerRight (F.mapId a) (self.app a)) (CategoryStruct.comp (Bicategory.leftUnitor (self.app a)).hom (Bicategory.rightUnitor (self.app a)).inv)
Oplax unity.
- naturality_comp {a b c : B} (f : a ⟶ b) (g : b ⟶ c) : CategoryStruct.comp (self.naturality (CategoryStruct.comp f g)) (Bicategory.whiskerLeft (self.app a) (G.mapComp f g)) = CategoryStruct.comp (Bicategory.whiskerRight (F.mapComp f g) (self.app c)) (CategoryStruct.comp (Bicategory.associator (F.map f) (F.map g) (self.app c)).hom (CategoryStruct.comp (Bicategory.whiskerLeft (F.map f) (self.naturality g)) (CategoryStruct.comp (Bicategory.associator (F.map f) (self.app b) (G.map g)).inv (CategoryStruct.comp (Bicategory.whiskerRight (self.naturality f) (G.map g)) (Bicategory.associator (self.app a) (G.map f) (G.map g)).hom))))
Oplax functoriality.
Instances For
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.
Instances For
The identity oplax transformation.
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Instances For
Equations
Vertical composition of oplax transformations.
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Instances For
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