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coe_comp {X Y Z : C} (f : X ⟶ Y) (g : Y ⟶ Z) : (f ≫ g : X → Z) = g ∘ f
(forget _).map_comp f g
lemma
category_theory.coe_comp
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[ "map_comp" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
id_apply {X : C} (x : X) : ((𝟙 X) : X → X) x = x
congr_fun ((forget _).map_id X) x
lemma
category_theory.id_apply
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[ "map_id" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
comp_apply {X Y Z : C} (f : X ⟶ Y) (g : Y ⟶ Z) (x : X) : (f ≫ g) x = g (f x)
congr_fun ((forget _).map_comp _ _) x
lemma
category_theory.comp_apply
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[ "map_comp" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
concrete_category.congr_hom {X Y : C} {f g : X ⟶ Y} (h : f = g) (x : X) : f x = g x
congr_fun (congr_arg (λ f : X ⟶ Y, (f : X → Y)) h) x
lemma
category_theory.concrete_category.congr_hom
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
concrete_category.congr_arg {X Y : C} (f : X ⟶ Y) {x x' : X} (h : x = x') : f x = f x'
congr_arg (f : X → Y) h
lemma
category_theory.concrete_category.congr_arg
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
concrete_category.mono_of_injective {X Y : C} (f : X ⟶ Y) (i : function.injective f) : mono f
(forget C).mono_of_mono_map ((mono_iff_injective f).2 i)
lemma
category_theory.concrete_category.mono_of_injective
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
In any concrete category, injective morphisms are monomorphisms.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
concrete_category.injective_of_mono_of_preserves_pullback {X Y : C} (f : X ⟶ Y) [mono f] [preserves_limits_of_shape walking_cospan (forget C)] : function.injective f
(mono_iff_injective ((forget C).map f)).mp infer_instance
lemma
category_theory.concrete_category.injective_of_mono_of_preserves_pullback
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
concrete_category.mono_iff_injective_of_preserves_pullback {X Y : C} (f : X ⟶ Y) [preserves_limits_of_shape walking_cospan (forget C)] : mono f ↔ function.injective f
((forget C).mono_map_iff_mono _).symm.trans (mono_iff_injective _)
lemma
category_theory.concrete_category.mono_iff_injective_of_preserves_pullback
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
concrete_category.epi_of_surjective {X Y : C} (f : X ⟶ Y) (s : function.surjective f) : epi f
(forget C).epi_of_epi_map ((epi_iff_surjective f).2 s)
lemma
category_theory.concrete_category.epi_of_surjective
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
In any concrete category, surjective morphisms are epimorphisms.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
concrete_category.surjective_of_epi_of_preserves_pushout {X Y : C} (f : X ⟶ Y) [epi f] [preserves_colimits_of_shape walking_span (forget C)] : function.surjective f
(epi_iff_surjective ((forget C).map f)).mp infer_instance
lemma
category_theory.concrete_category.surjective_of_epi_of_preserves_pushout
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
concrete_category.epi_iff_surjective_of_preserves_pushout {X Y : C} (f : X ⟶ Y) [preserves_colimits_of_shape walking_span (forget C)] : epi f ↔ function.surjective f
((forget C).epi_map_iff_epi _).symm.trans (epi_iff_surjective _)
lemma
category_theory.concrete_category.epi_iff_surjective_of_preserves_pushout
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
concrete_category.bijective_of_is_iso {X Y : C} (f : X ⟶ Y) [is_iso f] : function.bijective ((forget C).map f)
by { rw ← is_iso_iff_bijective, apply_instance, }
lemma
category_theory.concrete_category.bijective_of_is_iso
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
concrete_category.has_coe_to_fun_Type {X Y : Type u} (f : X ⟶ Y) : coe_fn f = f
rfl
lemma
category_theory.concrete_category.has_coe_to_fun_Type
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
has_forget₂ (C : Type u) (D : Type u') [category.{v} C] [concrete_category.{w} C] [category.{v'} D] [concrete_category.{w} D]
(forget₂ : C ⥤ D) (forget_comp : forget₂ ⋙ (forget D) = forget C . obviously)
class
category_theory.has_forget₂
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
`has_forget₂ C D`, where `C` and `D` are both concrete categories, provides a functor `forget₂ C D : C ⥤ D` and a proof that `forget₂ ⋙ (forget D) = forget C`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
forget₂ (C : Type u) (D : Type u') [category.{v} C] [concrete_category.{w} C] [category.{v'} D] [concrete_category.{w} D] [has_forget₂ C D] : C ⥤ D
has_forget₂.forget₂
def
category_theory.forget₂
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
The forgetful functor `C ⥤ D` between concrete categories for which we have an instance `has_forget₂ C `.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
forget₂_faithful (C : Type u) (D : Type u') [category.{v} C] [concrete_category.{w} C] [category.{v'} D] [concrete_category.{w} D] [has_forget₂ C D] : faithful (forget₂ C D)
has_forget₂.forget_comp.faithful_of_comp
instance
category_theory.forget₂_faithful
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
forget₂_preserves_monomorphisms (C : Type u) (D : Type u') [category.{v} C] [concrete_category.{w} C] [category.{v'} D] [concrete_category.{w} D] [has_forget₂ C D] [(forget C).preserves_monomorphisms] : (forget₂ C D).preserves_monomorphisms
have (forget₂ C D ⋙ forget D).preserves_monomorphisms, by { simp only [has_forget₂.forget_comp], apply_instance }, by exactI functor.preserves_monomorphisms_of_preserves_of_reflects _ (forget D)
instance
category_theory.forget₂_preserves_monomorphisms
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
forget₂_preserves_epimorphisms (C : Type u) (D : Type u') [category.{v} C] [concrete_category.{w} C] [category.{v'} D] [concrete_category.{w} D] [has_forget₂ C D] [(forget C).preserves_epimorphisms] : (forget₂ C D).preserves_epimorphisms
have (forget₂ C D ⋙ forget D).preserves_epimorphisms, by { simp only [has_forget₂.forget_comp], apply_instance }, by exactI functor.preserves_epimorphisms_of_preserves_of_reflects _ (forget D)
instance
category_theory.forget₂_preserves_epimorphisms
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
induced_category.concrete_category {C : Type u} {D : Type u'} [category.{v'} D] [concrete_category.{w} D] (f : C → D) : concrete_category.{w} (induced_category D f)
{ forget := induced_functor f ⋙ forget D }
instance
category_theory.induced_category.concrete_category
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
induced_category.has_forget₂ {C : Type u} {D : Type u'} [category.{v'} D] [concrete_category.{w} D] (f : C → D) : has_forget₂ (induced_category D f) D
{ forget₂ := induced_functor f, forget_comp := rfl }
instance
category_theory.induced_category.has_forget₂
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
full_subcategory.concrete_category {C : Type u} [category.{v} C] [concrete_category.{w} C] (Z : C → Prop) : concrete_category (full_subcategory Z)
{ forget := full_subcategory_inclusion Z ⋙ forget C }
instance
category_theory.full_subcategory.concrete_category
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
full_subcategory.has_forget₂ {C : Type u} [category.{v} C] [concrete_category.{w} C] (Z : C → Prop) : has_forget₂ (full_subcategory Z) C
{ forget₂ := full_subcategory_inclusion Z, forget_comp := rfl }
instance
category_theory.full_subcategory.has_forget₂
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
has_forget₂.mk' {C : Type u} {D : Type u'} [category.{v} C] [concrete_category.{w} C] [category.{v'} D] [concrete_category.{w} D] (obj : C → D) (h_obj : ∀ X, (forget D).obj (obj X) = (forget C).obj X) (map : Π {X Y}, (X ⟶ Y) → (obj X ⟶ obj Y)) (h_map : ∀ {X Y} {f : X ⟶ Y}, (forget D).map (map f) == (forget C).m...
{ forget₂ := faithful.div _ _ _ @h_obj _ @h_map, forget_comp := by apply faithful.div_comp }
def
category_theory.has_forget₂.mk'
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
In order to construct a “partially forgetting” functor, we do not need to verify functor laws; it suffices to ensure that compositions agree with `forget₂ C D ⋙ forget D = forget C`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
has_forget_to_Type (C : Type u) [category.{v} C] [concrete_category.{w} C] : has_forget₂ C (Type w)
{ forget₂ := forget C, forget_comp := functor.comp_id _ }
def
category_theory.has_forget_to_Type
category_theory.concrete_category
src/category_theory/concrete_category/basic.lean
[ "category_theory.types", "category_theory.functor.epi_mono", "category_theory.limits.constructions.epi_mono" ]
[]
Every forgetful functor factors through the identity functor. This is not a global instance as it is prone to creating type class resolution loops.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
bundled (c : Type u → Type v) : Type (max (u+1) v)
(α : Type u) (str : c α . tactic.apply_instance)
structure
category_theory.bundled
category_theory.concrete_category
src/category_theory/concrete_category/bundled.lean
[ "tactic.lint" ]
[]
`bundled` is a type bundled with a type class instance for that type. Only the type class is exposed as a parameter.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
of {c : Type u → Type v} (α : Type u) [str : c α] : bundled c
⟨α, str⟩
def
category_theory.bundled.of
category_theory.concrete_category
src/category_theory/concrete_category/bundled.lean
[ "tactic.lint" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_mk (α) (str) : (@bundled.mk c α str : Type u) = α
rfl
lemma
category_theory.bundled.coe_mk
category_theory.concrete_category
src/category_theory/concrete_category/bundled.lean
[ "tactic.lint" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map (f : Π {α}, c α → d α) (b : bundled c) : bundled d
⟨b, f b.str⟩
def
category_theory.bundled.map
category_theory.concrete_category
src/category_theory/concrete_category/bundled.lean
[ "tactic.lint" ]
[]
Map over the bundled structure
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
bundled_hom
(to_fun : Π {α β : Type u} (Iα : c α) (Iβ : c β), hom Iα Iβ → α → β) (id : Π {α : Type u} (I : c α), hom I I) (comp : Π {α β γ : Type u} (Iα : c α) (Iβ : c β) (Iγ : c γ), hom Iβ Iγ → hom Iα Iβ → hom Iα Iγ) (hom_ext : ∀ {α β : Type u} (Iα : c α) (Iβ : c β), function.injective (to_fun Iα Iβ) . obviously) (id_to_fun : ∀...
structure
category_theory.bundled_hom
category_theory.concrete_category
src/category_theory/concrete_category/bundled_hom.lean
[ "category_theory.concrete_category.basic", "category_theory.concrete_category.bundled" ]
[ "hom_ext" ]
Class for bundled homs. Note that the arguments order follows that of lemmas for `monoid_hom`. This way we can use `⟨@monoid_hom.to_fun, @monoid_hom.id ...⟩` in an instance.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
category : category (bundled c)
by refine { hom := λ X Y, @hom X Y X.str Y.str, id := λ X, @bundled_hom.id c hom 𝒞 X X.str, comp := λ X Y Z f g, @bundled_hom.comp c hom 𝒞 X Y Z X.str Y.str Z.str g f, comp_id' := _, id_comp' := _, assoc' := _}; intros; apply 𝒞.hom_ext; simp only [𝒞.id_to_fun, 𝒞.comp_to_fun, function.left_id, function....
instance
category_theory.bundled_hom.category
category_theory.concrete_category
src/category_theory/concrete_category/bundled_hom.lean
[ "category_theory.concrete_category.basic", "category_theory.concrete_category.bundled" ]
[]
Every `@bundled_hom c _` defines a category with objects in `bundled c`. This instance generates the type-class problem `bundled_hom ?m` (which is why this is marked as `[nolint]`). Currently that is not a problem, as there are almost no instances of `bundled_hom`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
concrete_category : concrete_category.{u} (bundled c)
{ forget := { obj := λ X, X, map := λ X Y f, 𝒞.to_fun X.str Y.str f, map_id' := λ X, 𝒞.id_to_fun X.str, map_comp' := by intros; erw 𝒞.comp_to_fun; refl }, forget_faithful := { map_injective' := by intros; apply 𝒞.hom_ext } }
instance
category_theory.bundled_hom.concrete_category
category_theory.concrete_category
src/category_theory/concrete_category/bundled_hom.lean
[ "category_theory.concrete_category.basic", "category_theory.concrete_category.bundled" ]
[]
A category given by `bundled_hom` is a concrete category. This instance generates the type-class problem `bundled_hom ?m` (which is why this is marked as `[nolint]`). Currently that is not a problem, as there are almost no instances of `bundled_hom`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mk_has_forget₂ {d : Type u → Type u} {hom_d : Π ⦃α β : Type u⦄ (Iα : d α) (Iβ : d β), Type u} [bundled_hom hom_d] (obj : Π ⦃α⦄, c α → d α) (map : Π {X Y : bundled c}, (X ⟶ Y) → ((bundled.map obj X) ⟶ (bundled.map obj Y))) (h_map : ∀ {X Y : bundled c} (f : X ⟶ Y), (map f : X → Y) = f) : has_forget₂ (bundled c) (...
has_forget₂.mk' (bundled.map @obj) (λ _, rfl) @map (by intros; apply heq_of_eq; apply h_map)
def
category_theory.bundled_hom.mk_has_forget₂
category_theory.concrete_category
src/category_theory/concrete_category/bundled_hom.lean
[ "category_theory.concrete_category.basic", "category_theory.concrete_category.bundled" ]
[]
A version of `has_forget₂.mk'` for categories defined using `@bundled_hom`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map_hom (F : Π {α}, d α → c α) : Π ⦃α β : Type u⦄ (Iα : d α) (Iβ : d β), Type u
λ α β iα iβ, hom (F iα) (F iβ)
def
category_theory.bundled_hom.map_hom
category_theory.concrete_category
src/category_theory/concrete_category/bundled_hom.lean
[ "category_theory.concrete_category.basic", "category_theory.concrete_category.bundled" ]
[]
The `hom` corresponding to first forgetting along `F`, then taking the `hom` associated to `c`. For typical usage, see the construction of `CommMon` from `Mon`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map (F : Π {α}, d α → c α) : bundled_hom (map_hom hom @F)
{ to_fun := λ α β iα iβ f, 𝒞.to_fun (F iα) (F iβ) f, id := λ α iα, 𝒞.id (F iα), comp := λ α β γ iα iβ iγ f g, 𝒞.comp (F iα) (F iβ) (F iγ) f g, hom_ext := λ α β iα iβ f g h, 𝒞.hom_ext (F iα) (F iβ) h }
def
category_theory.bundled_hom.map
category_theory.concrete_category
src/category_theory/concrete_category/bundled_hom.lean
[ "category_theory.concrete_category.basic", "category_theory.concrete_category.bundled" ]
[ "hom_ext" ]
Construct the `bundled_hom` induced by a map between type classes. This is useful for building categories such as `CommMon` from `Mon`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
parent_projection (F : Π {α}, d α → c α)
class
category_theory.bundled_hom.parent_projection
category_theory.concrete_category
src/category_theory/concrete_category/bundled_hom.lean
[ "category_theory.concrete_category.basic", "category_theory.concrete_category.bundled" ]
[]
We use the empty `parent_projection` class to label functions like `comm_monoid.to_monoid`, which we would like to use to automatically construct `bundled_hom` instances from. Once we've set up `Mon` as the category of bundled monoids, this allows us to set up `CommMon` by defining an instance ```instance : parent_pro...
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
bundled_hom_of_parent_projection (F : Π {α}, d α → c α) [parent_projection @F] : bundled_hom (map_hom hom @F)
map hom @F
instance
category_theory.bundled_hom.bundled_hom_of_parent_projection
category_theory.concrete_category
src/category_theory/concrete_category/bundled_hom.lean
[ "category_theory.concrete_category.basic", "category_theory.concrete_category.bundled" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
forget₂ (F : Π {α}, d α → c α) [parent_projection @F] : has_forget₂ (bundled d) (bundled c)
{ forget₂ := { obj := λ X, ⟨X, F X.2⟩, map := λ X Y f, f } }
instance
category_theory.bundled_hom.forget₂
category_theory.concrete_category
src/category_theory/concrete_category/bundled_hom.lean
[ "category_theory.concrete_category.basic", "category_theory.concrete_category.bundled" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
forget₂_full (F : Π {α}, d α → c α) [parent_projection @F] : full (forget₂ (bundled d) (bundled c))
{ preimage := λ X Y f, f }
instance
category_theory.bundled_hom.forget₂_full
category_theory.concrete_category
src/category_theory/concrete_category/bundled_hom.lean
[ "category_theory.concrete_category.basic", "category_theory.concrete_category.bundled" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
reflects_isomorphisms_forget₂ [has_forget₂ C D] [reflects_isomorphisms (forget C)] : reflects_isomorphisms (forget₂ C D)
{ reflects := λ X Y f i, begin resetI, haveI i' : is_iso ((forget D).map ((forget₂ C D).map f)) := functor.map_is_iso (forget D) _, haveI : is_iso ((forget C).map f) := begin have := has_forget₂.forget_comp, dsimp at this, rw ←this, exact i', end, apply is_iso_of_reflec...
lemma
category_theory.reflects_isomorphisms_forget₂
category_theory.concrete_category
src/category_theory/concrete_category/reflects_isomorphisms.lean
[ "category_theory.concrete_category.basic", "category_theory.functor.reflects_isomorphisms" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
unbundled_hom {c : Type u → Type u} (hom : Π {α β}, c α → c β → (α → β) → Prop)
(hom_id [] : ∀ {α} (ia : c α), hom ia ia id) (hom_comp [] : ∀ {α β γ} {Iα : c α} {Iβ : c β} {Iγ : c γ} {g : β → γ} {f : α → β} (hg : hom Iβ Iγ g) (hf : hom Iα Iβ f), hom Iα Iγ (g ∘ f))
class
category_theory.unbundled_hom
category_theory.concrete_category
src/category_theory/concrete_category/unbundled_hom.lean
[ "category_theory.concrete_category.bundled_hom" ]
[]
A class for unbundled homs used to define a category. `hom` must take two types `α`, `β` and instances of the corresponding structures, and return a predicate on `α → β`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
bundled_hom : bundled_hom (λ α β (Iα : c α) (Iβ : c β), subtype (hom Iα Iβ))
{ to_fun := λ _ _ _ _, subtype.val, id := λ α Iα, ⟨id, hom_id hom Iα⟩, id_to_fun := by intros; refl, comp := λ _ _ _ _ _ _ g f, ⟨g.1 ∘ f.1, hom_comp c g.2 f.2⟩, comp_to_fun := by intros; refl, hom_ext := by intros; apply subtype.eq }
instance
category_theory.unbundled_hom.bundled_hom
category_theory.concrete_category
src/category_theory/concrete_category/unbundled_hom.lean
[ "category_theory.concrete_category.bundled_hom" ]
[ "hom_ext" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mk_has_forget₂ : has_forget₂ (bundled c) (bundled c')
bundled_hom.mk_has_forget₂ obj (λ X Y f, ⟨f.val, map f.property⟩) (λ _ _ _, rfl)
def
category_theory.unbundled_hom.mk_has_forget₂
category_theory.concrete_category
src/category_theory/concrete_category/unbundled_hom.lean
[ "category_theory.concrete_category.bundled_hom" ]
[]
A custom constructor for forgetful functor between concrete categories defined using `unbundled_hom`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
algebra (F : C ⥤ C)
(A : C) (str : F.obj A ⟶ A)
structure
category_theory.endofunctor.algebra
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[ "algebra" ]
An algebra of an endofunctor; `str` stands for "structure morphism"
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
hom (A₀ A₁ : algebra F)
(f : A₀.1 ⟶ A₁.1) (h' : F.map f ≫ A₁.str = A₀.str ≫ f . obviously)
structure
category_theory.endofunctor.algebra.hom
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[ "algebra" ]
A morphism between algebras of endofunctor `F`
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
id : hom A A
{ f := 𝟙 _ }
def
category_theory.endofunctor.algebra.hom.id
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
The identity morphism of an algebra of endofunctor `F`
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
comp (f : hom A₀ A₁) (g : hom A₁ A₂) : hom A₀ A₂
{ f := f.1 ≫ g.1 }
def
category_theory.endofunctor.algebra.hom.comp
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
The composition of morphisms between algebras of endofunctor `F`
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
id_eq_id : algebra.hom.id A = 𝟙 A
rfl
lemma
category_theory.endofunctor.algebra.id_eq_id
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
id_f : (𝟙 _ : A ⟶ A).1 = 𝟙 A.1
rfl
lemma
category_theory.endofunctor.algebra.id_f
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
comp_eq_comp : algebra.hom.comp f g = f ≫ g
rfl
lemma
category_theory.endofunctor.algebra.comp_eq_comp
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
comp_f : (f ≫ g).1 = f.1 ≫ g.1
rfl
lemma
category_theory.endofunctor.algebra.comp_f
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
iso_mk (h : A₀.1 ≅ A₁.1) (w : F.map h.hom ≫ A₁.str = A₀.str ≫ h.hom) : A₀ ≅ A₁
{ hom := { f := h.hom }, inv := { f := h.inv, h' := by { rw [h.eq_comp_inv, category.assoc, ←w, ←functor.map_comp_assoc], simp } } }
def
category_theory.endofunctor.algebra.iso_mk
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
To construct an isomorphism of algebras, it suffices to give an isomorphism of the As which commutes with the structure morphisms.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
forget (F : C ⥤ C) : algebra F ⥤ C
{ obj := λ A, A.1, map := λ A B f, f.1 }
def
category_theory.endofunctor.algebra.forget
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[ "algebra" ]
The forgetful functor from the category of algebras, forgetting the algebraic structure.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
iso_of_iso (f : A₀ ⟶ A₁) [is_iso f.1] : is_iso f
⟨⟨{ f := inv f.1, h' := by { rw [is_iso.eq_comp_inv f.1, category.assoc, ← f.h], simp } }, by tidy⟩⟩
lemma
category_theory.endofunctor.algebra.iso_of_iso
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
An algebra morphism with an underlying isomorphism hom in `C` is an algebra isomorphism.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
forget_reflects_iso : reflects_isomorphisms (forget F)
{ reflects := λ A B, iso_of_iso }
instance
category_theory.endofunctor.algebra.forget_reflects_iso
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
forget_faithful : faithful (forget F)
{}
instance
category_theory.endofunctor.algebra.forget_faithful
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
epi_of_epi {X Y : algebra F} (f : X ⟶ Y) [h : epi f.1] : epi f
(forget F).epi_of_epi_map h
lemma
category_theory.endofunctor.algebra.epi_of_epi
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[ "algebra" ]
An algebra morphism with an underlying epimorphism hom in `C` is an algebra epimorphism.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mono_of_mono {X Y : algebra F} (f : X ⟶ Y) [h : mono f.1] : mono f
(forget F).mono_of_mono_map h
lemma
category_theory.endofunctor.algebra.mono_of_mono
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[ "algebra" ]
An algebra morphism with an underlying monomorphism hom in `C` is an algebra monomorphism.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
functor_of_nat_trans {F G : C ⥤ C} (α : G ⟶ F) : algebra F ⥤ algebra G
{ obj := λ A, { A := A.1, str := α.app A.1 ≫ A.str }, map := λ A₀ A₁ f, { f := f.1 } }
def
category_theory.endofunctor.algebra.functor_of_nat_trans
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[ "algebra" ]
From a natural transformation `α : G → F` we get a functor from algebras of `F` to algebras of `G`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
functor_of_nat_trans_id : functor_of_nat_trans (𝟙 F) ≅ 𝟭 _
nat_iso.of_components (λ X, iso_mk (iso.refl _) (by { dsimp, simp, })) (λ X Y f, by { ext, dsimp, simp })
def
category_theory.endofunctor.algebra.functor_of_nat_trans_id
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
The identity transformation induces the identity endofunctor on the category of algebras.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
functor_of_nat_trans_comp {F₀ F₁ F₂ : C ⥤ C} (α : F₀ ⟶ F₁) (β : F₁ ⟶ F₂) : functor_of_nat_trans (α ≫ β) ≅ functor_of_nat_trans β ⋙ functor_of_nat_trans α
nat_iso.of_components (λ X, iso_mk (iso.refl _) (by { dsimp, simp })) (λ X Y f, by { ext, dsimp, simp })
def
category_theory.endofunctor.algebra.functor_of_nat_trans_comp
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
A composition of natural transformations gives the composition of corresponding functors.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
functor_of_nat_trans_eq {F G : C ⥤ C} {α β : F ⟶ G} (h : α = β) : functor_of_nat_trans α ≅ functor_of_nat_trans β
nat_iso.of_components (λ X, iso_mk (iso.refl _) (by { dsimp, simp [h] })) (λ X Y f, by { ext, dsimp, simp })
def
category_theory.endofunctor.algebra.functor_of_nat_trans_eq
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
If `α` and `β` are two equal natural transformations, then the functors of algebras induced by them are isomorphic. We define it like this as opposed to using `eq_to_iso` so that the components are nicer to prove lemmas about.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
equiv_of_nat_iso {F G : C ⥤ C} (α : F ≅ G) : algebra F ≌ algebra G
{ functor := functor_of_nat_trans α.inv, inverse := functor_of_nat_trans α.hom, unit_iso := functor_of_nat_trans_id.symm ≪≫ functor_of_nat_trans_eq (by simp) ≪≫ functor_of_nat_trans_comp _ _, counit_iso := (functor_of_nat_trans_comp _ _).symm ≪≫ functor_of_nat_trans_eq (by simp) ≪≫ functor...
def
category_theory.endofunctor.algebra.equiv_of_nat_iso
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[ "algebra" ]
Naturally isomorphic endofunctors give equivalent categories of algebras. Furthermore, they are equivalent as categories over `C`, that is, we have `equiv_of_nat_iso h ⋙ forget = forget`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
str_inv : A.1 ⟶ F.obj A.1
(h.to ⟨ F.obj A.1 , F.map A.str ⟩).1
def
category_theory.endofunctor.algebra.initial.str_inv
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
The inverse of the structure map of an initial algebra
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
left_inv' : (⟨str_inv h ≫ A.str⟩ : A ⟶ A) = 𝟙 A
limits.is_initial.hom_ext h _ (𝟙 A)
lemma
category_theory.endofunctor.algebra.initial.left_inv'
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
left_inv : str_inv h ≫ A.str = 𝟙 _
congr_arg hom.f (left_inv' h)
lemma
category_theory.endofunctor.algebra.initial.left_inv
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
right_inv : A.str ≫ str_inv h = 𝟙 _
by { rw [str_inv, ← (h.to ⟨ F.obj A.1 , F.map A.str ⟩).h, ← F.map_id, ← F.map_comp], congr, exact (left_inv h) }
lemma
category_theory.endofunctor.algebra.initial.right_inv
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
str_is_iso (h : limits.is_initial A) : is_iso A.str
{ out := ⟨ str_inv h, right_inv _ , left_inv _ ⟩ }
lemma
category_theory.endofunctor.algebra.initial.str_is_iso
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
The structure map of the inital algebra is an isomorphism, hence endofunctors preserve their initial algebras
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coalgebra (F : C ⥤ C)
(V : C) (str : V ⟶ F.obj V)
structure
category_theory.endofunctor.coalgebra
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
A coalgebra of an endofunctor; `str` stands for "structure morphism"
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
hom (V₀ V₁ : coalgebra F)
(f : V₀.1 ⟶ V₁.1) (h' : V₀.str ≫ F.map f = f ≫ V₁.str . obviously)
structure
category_theory.endofunctor.coalgebra.hom
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
A morphism between coalgebras of an endofunctor `F`
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
id : hom V V
{ f := 𝟙 _ }
def
category_theory.endofunctor.coalgebra.hom.id
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
The identity morphism of an algebra of endofunctor `F`
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
comp (f : hom V₀ V₁) (g : hom V₁ V₂) : hom V₀ V₂
{ f := f.1 ≫ g.1 }
def
category_theory.endofunctor.coalgebra.hom.comp
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
The composition of morphisms between algebras of endofunctor `F`
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
id_eq_id : coalgebra.hom.id V = 𝟙 V
rfl
lemma
category_theory.endofunctor.coalgebra.id_eq_id
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
id_f : (𝟙 _ : V ⟶ V).1 = 𝟙 V.1
rfl
lemma
category_theory.endofunctor.coalgebra.id_f
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
comp_eq_comp : coalgebra.hom.comp f g = f ≫ g
rfl
lemma
category_theory.endofunctor.coalgebra.comp_eq_comp
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
iso_mk (h : V₀.1 ≅ V₁.1) (w : V₀.str ≫ F.map h.hom = h.hom ≫ V₁.str ) : V₀ ≅ V₁
{ hom := { f := h.hom }, inv := { f := h.inv, h' := by { rw [h.eq_inv_comp, ← category.assoc, ←w, category.assoc, ← functor.map_comp], simp only [iso.hom_inv_id, functor.map_id, category.comp_id] } } }
def
category_theory.endofunctor.coalgebra.iso_mk
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[ "functor.map_id" ]
To construct an isomorphism of coalgebras, it suffices to give an isomorphism of the Vs which commutes with the structure morphisms.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
forget (F : C ⥤ C) : coalgebra F ⥤ C
{ obj := λ A, A.1, map := λ A B f, f.1 }
def
category_theory.endofunctor.coalgebra.forget
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
The forgetful functor from the category of coalgebras, forgetting the coalgebraic structure.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
iso_of_iso (f : V₀ ⟶ V₁) [is_iso f.1] : is_iso f
⟨⟨{ f := inv f.1, h' := by { rw [is_iso.eq_inv_comp f.1, ← category.assoc, ← f.h, category.assoc], simp } }, by tidy⟩⟩
lemma
category_theory.endofunctor.coalgebra.iso_of_iso
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
A coalgebra morphism with an underlying isomorphism hom in `C` is a coalgebra isomorphism.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
epi_of_epi {X Y : coalgebra F} (f : X ⟶ Y) [h : epi f.1] : epi f
(forget F).epi_of_epi_map h
lemma
category_theory.endofunctor.coalgebra.epi_of_epi
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
An algebra morphism with an underlying epimorphism hom in `C` is an algebra epimorphism.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mono_of_mono {X Y : coalgebra F} (f : X ⟶ Y) [h : mono f.1] : mono f
(forget F).mono_of_mono_map h
lemma
category_theory.endofunctor.coalgebra.mono_of_mono
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
An algebra morphism with an underlying monomorphism hom in `C` is an algebra monomorphism.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
functor_of_nat_trans {F G : C ⥤ C} (α : F ⟶ G) : coalgebra F ⥤ coalgebra G
{ obj := λ V, { V := V.1, str := V.str ≫ α.app V.1 }, map := λ V₀ V₁ f, { f := f.1, h' := by rw [category.assoc, ← α.naturality, ← category.assoc, f.h, category.assoc] } }
def
category_theory.endofunctor.coalgebra.functor_of_nat_trans
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
From a natural transformation `α : F → G` we get a functor from coalgebras of `F` to coalgebras of `G`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
functor_of_nat_trans_comp {F₀ F₁ F₂ : C ⥤ C} (α : F₀ ⟶ F₁) (β : F₁ ⟶ F₂) : functor_of_nat_trans (α ≫ β) ≅ functor_of_nat_trans α ⋙ functor_of_nat_trans β
nat_iso.of_components (λ X, iso_mk (iso.refl _) (by { dsimp, simp })) (λ X Y f, by { ext, dsimp, simp })
def
category_theory.endofunctor.coalgebra.functor_of_nat_trans_comp
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
A composition of natural transformations gives the composition of corresponding functors.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
equiv_of_nat_iso {F G : C ⥤ C} (α : F ≅ G) : coalgebra F ≌ coalgebra G
{ functor := functor_of_nat_trans α.hom, inverse := functor_of_nat_trans α.inv, unit_iso := functor_of_nat_trans_id.symm ≪≫ functor_of_nat_trans_eq (by simp) ≪≫ functor_of_nat_trans_comp _ _, counit_iso := (functor_of_nat_trans_comp _ _).symm ≪≫ functor_of_nat_trans_eq (by simp) ≪≫ functor...
def
category_theory.endofunctor.coalgebra.equiv_of_nat_iso
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[]
Naturally isomorphic endofunctors give equivalent categories of coalgebras. Furthermore, they are equivalent as categories over `C`, that is, we have `equiv_of_nat_iso h ⋙ forget = forget`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
algebra.hom_equiv_naturality_str (adj : F ⊣ G) (A₁ A₂ : algebra F) (f : A₁ ⟶ A₂) : (adj.hom_equiv A₁.A A₁.A) A₁.str ≫ G.map f.f = f.f ≫ (adj.hom_equiv A₂.A A₂.A) A₂.str
by { rw [← adjunction.hom_equiv_naturality_right, ← adjunction.hom_equiv_naturality_left, f.h] }
lemma
category_theory.endofunctor.adjunction.algebra.hom_equiv_naturality_str
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[ "adj", "algebra" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coalgebra.hom_equiv_naturality_str_symm (adj : F ⊣ G) (V₁ V₂ : coalgebra G) (f : V₁ ⟶ V₂) : F.map f.f ≫ ((adj.hom_equiv V₂.V V₂.V).symm) V₂.str = ((adj.hom_equiv V₁.V V₁.V).symm) V₁.str ≫ f.f
by { rw [← adjunction.hom_equiv_naturality_left_symm, ← adjunction.hom_equiv_naturality_right_symm, f.h] }
lemma
category_theory.endofunctor.adjunction.coalgebra.hom_equiv_naturality_str_symm
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[ "adj" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
algebra.to_coalgebra_of (adj : F ⊣ G) : algebra F ⥤ coalgebra G
{ obj := λ A, { V := A.1, str := (adj.hom_equiv A.1 A.1).to_fun A.2 }, map := λ A₁ A₂ f, { f := f.1, h' := (algebra.hom_equiv_naturality_str adj A₁ A₂ f) } }
def
category_theory.endofunctor.adjunction.algebra.to_coalgebra_of
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[ "adj", "algebra" ]
Given an adjunction `F ⊣ G`, the functor that associates to an algebra over `F` a coalgebra over `G` defined via adjunction applied to the structure map.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coalgebra.to_algebra_of (adj : F ⊣ G) : coalgebra G ⥤ algebra F
{ obj := λ V, { A := V.1, str := (adj.hom_equiv V.1 V.1).inv_fun V.2 }, map := λ V₁ V₂ f, { f := f.1, h' := (coalgebra.hom_equiv_naturality_str_symm adj V₁ V₂ f) } }
def
category_theory.endofunctor.adjunction.coalgebra.to_algebra_of
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[ "adj", "algebra", "inv_fun" ]
Given an adjunction `F ⊣ G`, the functor that associates to a coalgebra over `G` an algebra over `F` defined via adjunction applied to the structure map.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
alg_coalg_equiv.unit_iso (adj : F ⊣ G) : 𝟭 (algebra F) ≅ (algebra.to_coalgebra_of adj) ⋙ (coalgebra.to_algebra_of adj)
{ hom := { app := λ A, { f := (𝟙 A.1), h' := by { erw [F.map_id, category.id_comp, category.comp_id], apply (adj.hom_equiv _ _).left_inv A.str } }, naturality' := λ A₁ A₂ f, by { ext1, dsimp, erw [category.id_comp, category.comp_id], refl } }, inv := { app := λ A, { f := (𝟙 A....
def
category_theory.endofunctor.adjunction.alg_coalg_equiv.unit_iso
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[ "adj", "algebra" ]
Given an adjunction, assigning to an algebra over the left adjoint a coalgebra over its right adjoint and going back is isomorphic to the identity functor.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
alg_coalg_equiv.counit_iso (adj : F ⊣ G) : (coalgebra.to_algebra_of adj) ⋙ (algebra.to_coalgebra_of adj) ≅ 𝟭 (coalgebra G)
{ hom := { app := λ V, { f := (𝟙 V.1), h' := by { dsimp, erw [G.map_id, category.id_comp, category.comp_id], apply (adj.hom_equiv _ _).right_inv V.str } }, naturality' := λ V₁ V₂ f, by { ext1, dsimp, erw [category.comp_id, category.id_comp], refl, } }, inv := { app := λ V, ...
def
category_theory.endofunctor.adjunction.alg_coalg_equiv.counit_iso
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[ "adj" ]
Given an adjunction, assigning to a coalgebra over the right adjoint an algebra over the left adjoint and going back is isomorphic to the identity functor.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
algebra_coalgebra_equiv (adj : F ⊣ G) : algebra F ≌ coalgebra G
{ functor := algebra.to_coalgebra_of adj, inverse := coalgebra.to_algebra_of adj, unit_iso := alg_coalg_equiv.unit_iso adj, counit_iso := alg_coalg_equiv.counit_iso adj, functor_unit_iso_comp' := λ A, by { ext, exact category.comp_id _ } }
def
category_theory.endofunctor.adjunction.algebra_coalgebra_equiv
category_theory.endofunctor
src/category_theory/endofunctor/algebra.lean
[ "category_theory.functor.reflects_isomorphisms", "category_theory.limits.shapes.terminal" ]
[ "adj", "algebra" ]
If `F` is left adjoint to `G`, then the category of algebras over `F` is equivalent to the category of coalgebras over `G`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
enriched_category (C : Type u₁)
(hom : C → C → V) (notation X ` ⟶[] ` Y:10 := hom X Y) (id : Π X, 𝟙_ V ⟶ (X ⟶[] X)) (comp : Π X Y Z, (X ⟶[] Y) ⊗ (Y ⟶[] Z) ⟶ (X ⟶[] Z)) (id_comp : Π X Y, (λ_ (X ⟶[] Y)).inv ≫ (id X ⊗ 𝟙 _) ≫ comp X X Y = 𝟙 _ . obviously) (comp_id : Π X Y, (ρ_ (X ⟶[] Y)).inv ≫ (𝟙 _ ⊗ id Y) ≫ comp X Y Y = 𝟙 _ . obviously) (assoc : ...
class
category_theory.enriched_category
category_theory.enriched
src/category_theory/enriched/basic.lean
[ "category_theory.monoidal.types.symmetric", "category_theory.monoidal.types.coyoneda", "category_theory.monoidal.center", "tactic.apply_fun" ]
[]
A `V`-category is a category enriched in a monoidal category `V`. Note that we do not assume that `V` is a concrete category, so there may not be an "honest" underlying category at all!
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
e_id (X : C) : 𝟙_ V ⟶ (X ⟶[V] X)
enriched_category.id X
def
category_theory.e_id
category_theory.enriched
src/category_theory/enriched/basic.lean
[ "category_theory.monoidal.types.symmetric", "category_theory.monoidal.types.coyoneda", "category_theory.monoidal.center", "tactic.apply_fun" ]
[]
The `𝟙_ V`-shaped generalized element giving the identity in a `V`-enriched category.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
e_comp (X Y Z : C) : (X ⟶[V] Y) ⊗ (Y ⟶[V] Z) ⟶ (X ⟶[V] Z)
enriched_category.comp X Y Z
def
category_theory.e_comp
category_theory.enriched
src/category_theory/enriched/basic.lean
[ "category_theory.monoidal.types.symmetric", "category_theory.monoidal.types.coyoneda", "category_theory.monoidal.center", "tactic.apply_fun" ]
[]
The composition `V`-morphism for a `V`-enriched category.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
e_id_comp (X Y : C) : (λ_ (X ⟶[V] Y)).inv ≫ (e_id V X ⊗ 𝟙 _) ≫ e_comp V X X Y = 𝟙 (X ⟶[V] Y)
enriched_category.id_comp X Y
lemma
category_theory.e_id_comp
category_theory.enriched
src/category_theory/enriched/basic.lean
[ "category_theory.monoidal.types.symmetric", "category_theory.monoidal.types.coyoneda", "category_theory.monoidal.center", "tactic.apply_fun" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
e_comp_id (X Y : C) : (ρ_ (X ⟶[V] Y)).inv ≫ (𝟙 _ ⊗ e_id V Y) ≫ e_comp V X Y Y = 𝟙 (X ⟶[V] Y)
enriched_category.comp_id X Y
lemma
category_theory.e_comp_id
category_theory.enriched
src/category_theory/enriched/basic.lean
[ "category_theory.monoidal.types.symmetric", "category_theory.monoidal.types.coyoneda", "category_theory.monoidal.center", "tactic.apply_fun" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
e_assoc (W X Y Z : C) : (α_ _ _ _).inv ≫ (e_comp V W X Y ⊗ 𝟙 _) ≫ e_comp V W Y Z = (𝟙 _ ⊗ e_comp V X Y Z) ≫ e_comp V W X Z
enriched_category.assoc W X Y Z
lemma
category_theory.e_assoc
category_theory.enriched
src/category_theory/enriched/basic.lean
[ "category_theory.monoidal.types.symmetric", "category_theory.monoidal.types.coyoneda", "category_theory.monoidal.center", "tactic.apply_fun" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
transport_enrichment (F : lax_monoidal_functor V W) (C : Type u₁)
C
def
category_theory.transport_enrichment
category_theory.enriched
src/category_theory/enriched/basic.lean
[ "category_theory.monoidal.types.symmetric", "category_theory.monoidal.types.coyoneda", "category_theory.monoidal.center", "tactic.apply_fun" ]
[]
A type synonym for `C`, which should come equipped with a `V`-enriched category structure. In a moment we will equip this with the `W`-enriched category structure obtained by applying the functor `F : lax_monoidal_functor V W` to each hom object.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
category_of_enriched_category_Type (C : Type u₁) [𝒞 : enriched_category (Type v) C] : category.{v} C
{ hom := 𝒞.hom, id := λ X, e_id (Type v) X punit.star, comp := λ X Y Z f g, e_comp (Type v) X Y Z ⟨f, g⟩, id_comp' := λ X Y f, congr_fun (e_id_comp (Type v) X Y) f, comp_id' := λ X Y f, congr_fun (e_comp_id (Type v) X Y) f, assoc' := λ W X Y Z f g h, (congr_fun (e_assoc (Type v) W X Y Z) ⟨f, g, h⟩ : _), }
def
category_theory.category_of_enriched_category_Type
category_theory.enriched
src/category_theory/enriched/basic.lean
[ "category_theory.monoidal.types.symmetric", "category_theory.monoidal.types.coyoneda", "category_theory.monoidal.center", "tactic.apply_fun" ]
[]
Construct an honest category from a `Type v`-enriched category.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
enriched_category_Type_of_category (C : Type u₁) [𝒞 : category.{v} C] : enriched_category (Type v) C
{ hom := 𝒞.hom, id := λ X p, 𝟙 X, comp := λ X Y Z p, p.1 ≫ p.2, id_comp := λ X Y, by { ext, simp, }, comp_id := λ X Y, by { ext, simp, }, assoc := λ W X Y Z, by { ext ⟨f, g, h⟩, simp, }, }
def
category_theory.enriched_category_Type_of_category
category_theory.enriched
src/category_theory/enriched/basic.lean
[ "category_theory.monoidal.types.symmetric", "category_theory.monoidal.types.coyoneda", "category_theory.monoidal.center", "tactic.apply_fun" ]
[]
Construct a `Type v`-enriched category from an honest category.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
enriched_category_Type_equiv_category (C : Type u₁) : (enriched_category (Type v) C) ≃ category.{v} C
{ to_fun := λ 𝒞, by exactI category_of_enriched_category_Type C, inv_fun := λ 𝒞, by exactI enriched_category_Type_of_category C, left_inv := λ 𝒞, begin cases 𝒞, dsimp [enriched_category_Type_of_category], congr, { ext X ⟨⟩, refl, }, { ext X Y Z ⟨f, g⟩, refl, } end, right_inv := λ 𝒞, by ...
def
category_theory.enriched_category_Type_equiv_category
category_theory.enriched
src/category_theory/enriched/basic.lean
[ "category_theory.monoidal.types.symmetric", "category_theory.monoidal.types.coyoneda", "category_theory.monoidal.center", "tactic.apply_fun" ]
[ "inv_fun" ]
We verify that an enriched category in `Type u` is just the same thing as an honest category.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
forget_enrichment (W : Type (v+1)) [category.{v} W] [monoidal_category W] (C : Type u₁) [enriched_category W C]
C
def
category_theory.forget_enrichment
category_theory.enriched
src/category_theory/enriched/basic.lean
[ "category_theory.monoidal.types.symmetric", "category_theory.monoidal.types.coyoneda", "category_theory.monoidal.center", "tactic.apply_fun" ]
[]
A type synonym for `C`, which should come equipped with a `V`-enriched category structure. In a moment we will equip this with the (honest) category structure so that `X ⟶ Y` is `(𝟙_ W) ⟶ (X ⟶[W] Y)`. We obtain this category by transporting the enrichment in `V` along the lax monoidal functor `coyoneda_tensor_unit`, ...
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83