Left actions from a monoidal category on a category #
Given a monoidal category C
, and a category D
, we define a left action of
C
on D
as the data of an object c ⊙ₗ d
of D
for every
c : C
and d : D
, as well as the data required to turn - ⊙ₗ -
into
a bifunctor, along with structure natural isomorphisms
(- ⊗ -) ⊙ₗ - ≅ - ⊙ₗ - ⊙ₗ -
and 𝟙_ C ⊙ₗ - ≅ -
, subject to coherence conditions.
References #
TODOs/Projects #
- Equivalence between actions of
C
onD
and pseudofunctors from the classifying bicategory ofC
toCat
. - Right actions
- Functors that respects left actions.
- Left actions as monoidal functors C ⥤ (D ⥤ D)ᴹᵒᵖ.
- Action of
(C ⥤ C)
onC
. - Modules in
D
over a monoid object inC
. Equivalence withMod_
whenD
isC
. - Given a monad
M
onC
, equivalence betweenAlgebra M
, and modules inC
onM.toMon : Mon_ (C ⥤ C)
. - Canonical action of
Type u
onu
-small cocomplete categories via the copower.
A class that carries the non-Prop data required to define a left action of a
monoidal category C
on a category D
, to set up notations.
- actionObj : C → D → D
The left action on objects. This is denoted
c ⊙ₗ d
. The left action of a map
f : c ⟶ c'
inC
on an objectd
inD
. If we are to consider the action as a functorΑ : C ⥤ D ⥤ D
, this is (Α.map f).app d. This is denoted
f ⊵ₗ d`The action of an object
c : C
on a mapf : d ⟶ d'
inD
. If we are to consider the action as a functorΑ : C ⥤ D ⥤ D
, this is (Α.obj c).map f. This is denoted
c ⊴ₗ f`.The action of a pair of maps
f : c ⟶ c'
andd ⟶ d'
. By default, this is defined in terms ofactionHomLeft
andactionHomRight
.The structural isomorphism
(c ⊗ c') ⊙ₗ d ≅ c ⊙ₗ (c' ⊙ₗ d)
.The structural isomorphism between
𝟙_ C ⊙ₗ d
andd
.
Instances
Notation for actionObj
, the action of C
on D
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Notation for actionHomLeft
, the action of C
on morphisms in D
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Notation for actionHomRight
, the action of morphism in C
on D
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Notation for actionHom
, the bifunctorial action of morphisms in C
and
D
on - ⊙ₗ -
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Notation for actionAssocIso
, the structural isomorphism
- ⊗ - ⊙ₗ - ≅ - ⊙ₗ - ⊙ₗ -
.
Equations
- CategoryTheory.MonoidalCategory.MonoidalLeftAction.termαₗ = Lean.ParserDescr.node `CategoryTheory.MonoidalCategory.MonoidalLeftAction.termαₗ 1024 (Lean.ParserDescr.symbol "αₗ ")
Instances For
Notation for actionUnitIso
, the structural isomorphism 𝟙_ C ⊙ₗ - ≅ -
.
Equations
- CategoryTheory.MonoidalCategory.MonoidalLeftAction.«termλₗ» = Lean.ParserDescr.node `CategoryTheory.MonoidalCategory.MonoidalLeftAction.«termλₗ» 1024 (Lean.ParserDescr.symbol "λₗ ")
Instances For
Notation for actionUnitIso
, the structural isomorphism 𝟙_ C ⊙ₗ - ≅ -
,
allowing one to specify the acting category.
Equations
- One or more equations did not get rendered due to their size.
Instances For
A MonoidalLeftAction C D
is is the data of:
- For every object
c : C
andd : D
, an objectc ⊙ₗ d
ofD
. - For every morphism
f : (c : C) ⟶ c'
and everyd : D
, a morphismf ⊵ₗ d : c ⊙ₗ d ⟶ c' ⊙ₗ d
. - For every morphism
f : (d : D) ⟶ d'
and everyc : C
, a morphismc ⊴ₗ f : c ⊙ₗ d ⟶ c ⊙ₗ d'
. - For every pair of morphisms
f : (c : C) ⟶ c'
andf : (d : D) ⟶ d'
, a morphismf ⊙ₗ f' : c ⊙ₗ d ⟶ c' ⊙ₗ d'
. - A structure isomorphism
αₗ c c' d : c ⊗ c' ⊙ₗ d ≅ c ⊙ₗ c' ⊙ₗ d
. - A structure isomorphism
λₗ d : (𝟙_ C) ⊙ₗ d ≅ d
. Furthermore, we require identities that turn- ⊙ₗ -
into a bifunctor, ensure naturality ofαₗ
andλₗ
, and ensure compatibilies with the associator and unitor isomorphisms inC
.
- actionObj : C → D → D
- actionHom_def {c c' : C} {d d' : D} (f : c ⟶ c') (g : d ⟶ d') : actionHom f g = CategoryStruct.comp (actionHomLeft f d) (actionHomRight c' g)
- actionHomRight_id (c : C) (d : D) : actionHomRight c (CategoryStruct.id d) = CategoryStruct.id (actionObj c d)
- id_actionHomLeft (c : C) (d : D) : actionHomLeft (CategoryStruct.id c) d = CategoryStruct.id (actionObj c d)
- actionHom_comp {c c' c'' : C} {d d' d'' : D} (f₁ : c ⟶ c') (f₂ : c' ⟶ c'') (g₁ : d ⟶ d') (g₂ : d' ⟶ d'') : actionHom (CategoryStruct.comp f₁ f₂) (CategoryStruct.comp g₁ g₂) = CategoryStruct.comp (actionHom f₁ g₁) (actionHom f₂ g₂)
- actionAssocIso_hom_naturality {c₁ c₂ c₃ c₄ : C} {d₁ d₂ : D} (f : c₁ ⟶ c₂) (g : c₃ ⟶ c₄) (h : d₁ ⟶ d₂) : CategoryStruct.comp (actionHom (tensorHom f g) h) (actionAssocIso c₂ c₄ d₂).hom = CategoryStruct.comp (actionAssocIso c₁ c₃ d₁).hom (actionHom f (actionHom g h))
- actionUnitIso_hom_naturality {d d' : D} (f : d ⟶ d') : CategoryStruct.comp (actionUnitIso d).hom f = CategoryStruct.comp (actionHomRight (tensorUnit C) f) (actionUnitIso d').hom
- whiskerLeft_actionHomLeft (c : C) {c' c'' : C} (f : c' ⟶ c'') (d : D) : actionHomLeft (whiskerLeft c f) d = CategoryStruct.comp (actionAssocIso c c' d).hom (CategoryStruct.comp (actionHomRight c (actionHomLeft f d)) (actionAssocIso c c'' d).inv)
- whiskerRight_actionHomLeft {c c' : C} (c'' : C) (f : c ⟶ c') (d : D) : actionHomLeft (whiskerRight f c'') d = CategoryStruct.comp (actionAssocIso c c'' d).hom (CategoryStruct.comp (actionHomLeft f (actionObj c'' d)) (actionAssocIso c' c'' d).inv)
- associator_actionHom (c₁ c₂ c₃ : C) (d : D) : CategoryStruct.comp (actionHomLeft (associator c₁ c₂ c₃).hom d) (CategoryStruct.comp (actionAssocIso c₁ (tensorObj c₂ c₃) d).hom (actionHomRight c₁ (actionAssocIso c₂ c₃ d).hom)) = CategoryStruct.comp (actionAssocIso (tensorObj c₁ c₂) c₃ d).hom (actionAssocIso c₁ c₂ (actionObj c₃ d)).hom
- leftUnitor_actionHom (c : C) (d : D) : actionHomLeft (leftUnitor c).hom d = CategoryStruct.comp (actionAssocIso (tensorUnit C) c d).hom (actionUnitIso (actionObj c d)).hom
- rightUnitor_actionHom (c : C) (d : D) : actionHomLeft (rightUnitor c).hom d = CategoryStruct.comp (actionAssocIso c (tensorUnit C) d).hom (actionHomRight c (actionUnitIso d).hom)
Instances
A monoidal category acts on itself through the tensor product.
Equations
- One or more equations did not get rendered due to their size.
Bundle the action of C
on D
as a functor C ⥤ D ⥤ D
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Bundle d ↦ c ⊙ₗ d
as a functor.
Equations
Instances For
Bundle c ↦ c ⊙ₗ d
as a functor.
Equations
Instances For
Bundle αₗ _ _ _
as an isomorphism of trifunctors.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Bundle λₗ _
as an isomorphism of functors.
Equations
- One or more equations did not get rendered due to their size.