- lift : Π (s : category_theory.limits.cone F), s.X ⟶ t.X
- fac' : (∀ (s : category_theory.limits.cone F) (j : J), c.lift s ≫ t.π.app j = s.π.app j) . "obviously"
- uniq' : (∀ (s : category_theory.limits.cone F) (m : s.X ⟶ t.X), (∀ (j : J), m ≫ t.π.app j = s.π.app j) → m = c.lift s) . "obviously"
A cone t
on F
is a limit cone if each cone on F
admits a unique
cone morphism to t
.
Equations
The universal morphism from any other cone to a limit cone.
Alternative constructor for is_limit
,
providing a morphism of cones rather than a morphism between the cone points
and separately the factorisation condition.
Equations
- category_theory.limits.is_limit.mk_cone_morphism lift uniq' = {lift := λ (s : category_theory.limits.cone F), (lift s).hom, fac' := _, uniq' := _}
Limit cones on F
are unique up to isomorphism.
Equations
- P.unique_up_to_iso Q = {hom := Q.lift_cone_morphism s, inv := P.lift_cone_morphism t, hom_inv_id' := _, inv_hom_id' := _}
Any cone morphism between limit cones is an isomorphism.
Equations
- P.hom_is_iso Q f = {inv := P.lift_cone_morphism t, hom_inv_id' := _, inv_hom_id' := _}
Limits of F
are unique up to isomorphism.
Equations
Transport evidence that a cone is a limit cone across an isomorphism of cones.
Equations
- P.of_iso_limit i = category_theory.limits.is_limit.mk_cone_morphism (λ (s : category_theory.limits.cone F), P.lift_cone_morphism s ≫ i.hom) _
If the canonical morphism from a cone point to a limiting cone point is an iso, then the first cone was limiting also.
Equations
Two morphisms into a limit are equal if their compositions with each cone morphism are equal.
Given a right adjoint functor between categories of cones, the image of a limit cone is a limit cone.
Equations
Given two functors which have equivalent categories of cones, we can transport a limiting cone across the equivalence.
Equations
- category_theory.limits.is_limit.of_cone_equiv h = {to_fun := λ (P : category_theory.limits.is_limit (h.functor.obj c)), (category_theory.limits.is_limit.of_right_adjoint h.inverse P).of_iso_limit (h.unit_iso.symm.app c), inv_fun := category_theory.limits.is_limit.of_right_adjoint h.functor c, left_inv := _, right_inv := _}
A cone postcomposed with a natural isomorphism is a limit cone if and only if the original cone is.
A cone postcomposed with the inverse of a natural isomorphism is a limit cone if and only if the original cone is.
The cone points of two limit cones for naturally isomorphic functors are themselves isomorphic.
Equations
- P.cone_points_iso_of_nat_iso Q w = {hom := Q.lift ((category_theory.limits.cones.postcompose w.hom).obj s), inv := P.lift ((category_theory.limits.cones.postcompose w.inv).obj t), hom_inv_id' := _, inv_hom_id' := _}
If s : cone F
is a limit cone, so is s
whiskered by an equivalence e
.
We can prove two cone points (s : cone F).X
and (t.cone F).X
are isomorphic if
- both cones are limit cones
- their indexing categories are equivalent via some
e : J ≌ K
, - the triangle of functors commutes up to a natural isomorphism:
e.functor ⋙ G ≅ F
.
This is the most general form of uniqueness of cone points, allowing relabelling of both the indexing category (up to equivalence) and the functor (up to natural isomorphism).
Equations
- P.cone_points_iso_of_equivalence Q e w = let w' : e.inverse ⋙ F ≅ G := (category_theory.iso_whisker_left e.inverse w).symm ≪≫ e.inv_fun_id_assoc G in {hom := Q.lift ((category_theory.limits.cones.equivalence_of_reindexing e.symm w').functor.obj s), inv := P.lift ((category_theory.limits.cones.equivalence_of_reindexing e w).functor.obj t), hom_inv_id' := _, inv_hom_id' := _}
The universal property of a limit cone: a map W ⟶ X
is the same as
a cone on F
with vertex W
.
The limit of F
represents the functor taking W
to
the set of cones on F
with vertex W
.
Equations
- h.nat_iso = category_theory.nat_iso.of_components (λ (W : Cᵒᵖ), h.hom_iso (opposite.unop W)) _
Another, more explicit, formulation of the universal property of a limit cone.
See also hom_iso
.
If G : C → D is a faithful functor which sends t to a limit cone, then it suffices to check that the induced maps for the image of t can be lifted to maps of C.
If F
and G
are naturally isomorphic, then F.map_cone c
being a limit implies
G.map_cone c
is also a limit.
Equations
- category_theory.limits.is_limit.map_cone_equiv h t = {lift := λ (s : category_theory.limits.cone (K ⋙ G)), t.lift ((category_theory.limits.cones.postcompose (category_theory.iso_whisker_left K h).inv).obj s) ≫ h.hom.app c.X, fac' := _, uniq' := _}
A cone is a limit cone exactly if there is a unique cone morphism from any other cone.
Equations
- category_theory.limits.is_limit.iso_unique_cone_morphism = {hom := λ (h : category_theory.limits.is_limit t) (s : category_theory.limits.cone F), {to_inhabited := {default := h.lift_cone_morphism s}, uniq := _}, inv := λ (h : Π (s : category_theory.limits.cone F), unique (s ⟶ t)), {lift := λ (s : category_theory.limits.cone F), (inhabited.default (s ⟶ t)).hom, fac' := _, uniq' := _}, hom_inv_id' := _, inv_hom_id' := _}
If F.cones
is represented by X
, each morphism f : Y ⟶ X
gives a cone with cone point Y
.
Equations
- category_theory.limits.is_limit.of_nat_iso.cone_of_hom h f = {X := Y, π := h.hom.app (opposite.op Y) f}
If F.cones
is represented by X
, each cone s
gives a morphism s.X ⟶ X
.
Equations
If F.cones
is represented by X
, the cone corresponding to the identity morphism on X
will be a limit cone.
If F.cones
is represented by X
, the cone corresponding to a morphism f : Y ⟶ X
is
the limit cone extended by f
.
If F.cones
is represented by X
, any cone is the extension of the limit cone by the
corresponding morphism.
If F.cones
is representable, then the cone corresponding to the identity morphism on
the representing object is a limit cone.
Equations
- category_theory.limits.is_limit.of_nat_iso h = {lift := λ (s : category_theory.limits.cone F), category_theory.limits.is_limit.of_nat_iso.hom_of_cone h s, fac' := _, uniq' := _}
- desc : Π (s : category_theory.limits.cocone F), t.X ⟶ s.X
- fac' : (∀ (s : category_theory.limits.cocone F) (j : J), t.ι.app j ≫ c.desc s = s.ι.app j) . "obviously"
- uniq' : (∀ (s : category_theory.limits.cocone F) (m : t.X ⟶ s.X), (∀ (j : J), t.ι.app j ≫ m = s.ι.app j) → m = c.desc s) . "obviously"
A cocone t
on F
is a colimit cocone if each cocone on F
admits a unique
cocone morphism from t
.
Equations
The universal morphism from a colimit cocone to any other cone.
Alternative constructor for is_colimit
,
providing a morphism of cocones rather than a morphism between the cocone points
and separately the factorisation condition.
Equations
- category_theory.limits.is_colimit.mk_cocone_morphism desc uniq' = {desc := λ (s : category_theory.limits.cocone F), (desc s).hom, fac' := _, uniq' := _}
Colimit cocones on F
are unique up to isomorphism.
Equations
- P.unique_up_to_iso Q = {hom := P.desc_cocone_morphism t, inv := Q.desc_cocone_morphism s, hom_inv_id' := _, inv_hom_id' := _}
Any cocone morphism between colimit cocones is an isomorphism.
Equations
- P.hom_is_iso Q f = {inv := Q.desc_cocone_morphism s, hom_inv_id' := _, inv_hom_id' := _}
Colimits of F
are unique up to isomorphism.
Equations
Transport evidence that a cocone is a colimit cocone across an isomorphism of cocones.
Equations
- P.of_iso_colimit i = category_theory.limits.is_colimit.mk_cocone_morphism (λ (s : category_theory.limits.cocone F), i.inv ≫ P.desc_cocone_morphism s) _
If the canonical morphism to a cocone point from a colimiting cocone point is an iso, then the first cocone was colimiting also.
Equations
Two morphisms out of a colimit are equal if their compositions with each cocone morphism are equal.
Given a left adjoint functor between categories of cocones, the image of a colimit cocone is a colimit cocone.
Equations
Given two functors which have equivalent categories of cocones, we can transport a colimiting cocone across the equivalence.
Equations
- category_theory.limits.is_colimit.of_cocone_equiv h = {to_fun := λ (P : category_theory.limits.is_colimit (h.functor.obj c)), (category_theory.limits.is_colimit.of_left_adjoint h.inverse P).of_iso_colimit (h.unit_iso.symm.app c), inv_fun := category_theory.limits.is_colimit.of_left_adjoint h.functor c, left_inv := _, right_inv := _}
A cocone precomposed with a natural isomorphism is a colimit cocone if and only if the original cocone is.
A cocone precomposed with the inverse of a natural isomorphism is a colimit cocone if and only if the original cocone is.
The cocone points of two colimit cocones for naturally isomorphic functors are themselves isomorphic.
Equations
- P.cocone_points_iso_of_nat_iso Q w = {hom := P.desc ((category_theory.limits.cocones.precompose w.hom).obj t), inv := Q.desc ((category_theory.limits.cocones.precompose w.inv).obj s), hom_inv_id' := _, inv_hom_id' := _}
If s : cone F
is a limit cone, so is s
whiskered by an equivalence e
.
We can prove two cocone points (s : cocone F).X
and (t.cocone F).X
are isomorphic if
- both cocones are colimit ccoones
- their indexing categories are equivalent via some
e : J ≌ K
, - the triangle of functors commutes up to a natural isomorphism:
e.functor ⋙ G ≅ F
.
This is the most general form of uniqueness of cocone points, allowing relabelling of both the indexing category (up to equivalence) and the functor (up to natural isomorphism).
Equations
- P.cocone_points_iso_of_equivalence Q e w = let w' : e.inverse ⋙ F ≅ G := (category_theory.iso_whisker_left e.inverse w).symm ≪≫ e.inv_fun_id_assoc G in {hom := P.desc ((category_theory.limits.cocones.equivalence_of_reindexing e w).functor.obj t), inv := Q.desc ((category_theory.limits.cocones.equivalence_of_reindexing e.symm w').functor.obj s), hom_inv_id' := _, inv_hom_id' := _}
The universal property of a colimit cocone: a map X ⟶ W
is the same as
a cocone on F
with vertex W
.
The colimit of F
represents the functor taking W
to
the set of cocones on F
with vertex W
.
Equations
Another, more explicit, formulation of the universal property of a colimit cocone.
See also hom_iso
.
If G : C → D is a faithful functor which sends t to a colimit cocone, then it suffices to check that the induced maps for the image of t can be lifted to maps of C.
A cocone is a colimit cocone exactly if there is a unique cocone morphism from any other cocone.
Equations
- category_theory.limits.is_colimit.iso_unique_cocone_morphism = {hom := λ (h : category_theory.limits.is_colimit t) (s : category_theory.limits.cocone F), {to_inhabited := {default := h.desc_cocone_morphism s}, uniq := _}, inv := λ (h : Π (s : category_theory.limits.cocone F), unique (t ⟶ s)), {desc := λ (s : category_theory.limits.cocone F), (inhabited.default (t ⟶ s)).hom, fac' := _, uniq' := _}, hom_inv_id' := _, inv_hom_id' := _}
If F.cocones
is corepresented by X
, each morphism f : X ⟶ Y
gives a cocone with cone point Y
.
If F.cocones
is corepresented by X
, each cocone s
gives a morphism X ⟶ s.X
.
If F.cocones
is corepresented by X
, the cocone corresponding to the identity morphism on X
will be a colimit cocone.
If F.cocones
is corepresented by X
, the cocone corresponding to a morphism f : Y ⟶ X
is
the colimit cocone extended by f
.
If F.cocones
is corepresented by X
, any cocone is the extension of the colimit cocone by the
corresponding morphism.
If F.cocones
is corepresentable, then the cocone corresponding to the identity morphism on
the representing object is a colimit cocone.
Equations
- category_theory.limits.is_colimit.of_nat_iso h = {desc := λ (s : category_theory.limits.cocone F), category_theory.limits.is_colimit.of_nat_iso.hom_of_cocone h s, fac' := _, uniq' := _}
- cone : category_theory.limits.cone F
- is_limit : category_theory.limits.is_limit category_theory.limits.has_limit.cone
has_limit F
represents a particular chosen limit of the diagram F
.
Instances
- category_theory.limits.has_limit_of_has_limits_of_shape
- category_theory.limits.has_product_of_has_biproduct
- category_theory.limits.has_limit_equivalence_comp
- category_theory.limits.has_binary_biproduct.has_limit_pair
- AddCommGroup.has_limit.has_limit_discrete
- category_theory.adjunction.has_limit_comp_equivalence
- category_theory.under.has_limit
- category_theory.comp_comparison_forget_has_limit
- category_theory.comp_comparison_has_limit
- has_limit : Π (F : J ⥤ C), category_theory.limits.has_limit F
C
has limits of shape J
if we have chosen a particular limit of
every functor F : J ⥤ C
.
Instances
- category_theory.limits.has_limits_of_shape_of_has_limits
- category_theory.limits.has_limits_of_shape_of_has_finite_limits
- category_theory.limits.has_limits_of_shape_wide_pullback_shape
- category_theory.limits.has_limits_of_shape_discrete
- category_theory.limits.functor_category_has_limits_of_shape
- category_theory.under.has_limits_of_shape
- category_theory.over.has_connected_limits
- has_limits_of_shape : Π (J : Type ?) [𝒥 : category_theory.small_category J], category_theory.limits.has_limits_of_shape J C
C
has all (small) limits if it has limits of every shape.
Instances
- category_theory.limits.has_limits_of_complete_lattice
- category_theory.limits.types.category_theory.limits.has_limits
- Mon.has_limits
- AddMon.has_limits
- CommMon.has_limits
- AddCommMon.has_limits
- Group.has_limits
- AddGroup.has_limits
- CommGroup.has_limits
- AddCommGroup.has_limits
- Module.has_limits
- SemiRing.has_limits
- CommSemiRing.has_limits
- Ring.has_limits
- CommRing.has_limits
- Algebra.has_limits
- category_theory.limits.functor_category_has_limits
- category_theory.under.has_limits
- category_theory.limits.category_theory.limits.has_limits
- category_theory.over.has_limits
- Top.Top_has_limits
The chosen limit cone of a functor.
The chosen limit object of a functor.
Equations
The projection from the chosen limit object to a value of the functor.
Equations
Evidence that the chosen cone is a limit cone.
The morphism from the cone point of any other cone to the chosen limit object.
Equations
The cone morphism from any cone to the chosen limit cone.
The isomorphism (in Type
) between
morphisms from a specified object W
to the limit object,
and cones with cone point W
.
Equations
The isomorphism (in Type
) between
morphisms from a specified object W
to the limit object,
and an explicit componentwise description of cones with cone point W
.
Equations
If we've chosen a limit for a functor F
,
we can transport that choice across a natural isomorphism.
Equations
- category_theory.limits.has_limit_of_iso α = {cone := (category_theory.limits.cones.postcompose α.hom).obj (category_theory.limits.limit.cone F), is_limit := {lift := λ (s : category_theory.limits.cone G), category_theory.limits.limit.lift F ((category_theory.limits.cones.postcompose α.inv).obj s), fac' := _, uniq' := _}}
If a functor G
has the same collection of cones as a functor F
which has a limit, then G
also has a limit.
The chosen limits of F : J ⥤ C
and G : J ⥤ C
are isomorphic,
if the functors are naturally isomorphic.
The chosen limits of F : J ⥤ C
and G : K ⥤ C
are isomorphic,
if there is an equivalence e : J ≌ K
making the triangle commute up to natural isomorphism.
The canonical morphism
from the chosen limit of F
to the chosen limit of E ⋙ F
.
Equations
- category_theory.limits.limit.pre F E = category_theory.limits.limit.lift (E ⋙ F) {X := category_theory.limits.limit F _inst_4, π := {app := λ (k : K), category_theory.limits.limit.π F (E.obj k), naturality' := _}}
The canonical morphism
from G
applied to the chosen limit of F
to the chosen limit of F ⋙ G
.
Equations
- category_theory.limits.limit.post F G = category_theory.limits.limit.lift (F ⋙ G) {X := G.obj (category_theory.limits.limit F), π := {app := λ (j : J), G.map (category_theory.limits.limit.π F j), naturality' := _}}
If a E ⋙ F
has a chosen limit, and E
is an equivalence, we can construct a chosen limit of F
.
Functoriality of limits.
Usually this morphism should be accessed through lim.map
,
but may be needed separately when you have specified limits for the source and target functors,
but not necessarily for all functors of shape J
.
Equations
- category_theory.limits.lim_map α = category_theory.limits.limit.lift G {X := category_theory.limits.limit F _inst_4, π := {app := λ (j : J), category_theory.limits.limit.π F j ≫ α.app j, naturality' := _}}
limit F
is functorial in F
, when C
has all limits of shape J
.
Equations
- category_theory.limits.lim = {obj := λ (F : J ⥤ C), category_theory.limits.limit F, map := λ (F G : J ⥤ C) (α : F ⟶ G), category_theory.limits.lim_map α, map_id' := _, map_comp' := _}
The isomorphism between
morphisms from W
to the cone point of the limit cone for F
and cones over F
with cone point W
is natural in F
.
Equations
- category_theory.limits.lim_yoneda = category_theory.nat_iso.of_components (λ (F : J ⥤ C), category_theory.nat_iso.of_components (λ (W : Cᵒᵖ), category_theory.limits.limit.hom_iso F (opposite.unop W)) _) category_theory.limits.lim_yoneda._proof_2
We can transport chosen limits of shape J
along an equivalence J ≌ J'
.
Equations
- cocone : category_theory.limits.cocone F
- is_colimit : category_theory.limits.is_colimit category_theory.limits.has_colimit.cocone
has_colimit F
represents a particular chosen colimit of the diagram F
.
Instances
- category_theory.limits.has_colimit_of_has_colimits_of_shape
- category_theory.limits.has_coproduct_of_has_biproduct
- category_theory.limits.has_colimit_equivalence_comp
- category_theory.limits.has_binary_biproduct.has_colimit_pair
- category_theory.adjunction.has_colimit_comp_equivalence
- category_theory.over.has_colimit
- has_colimit : Π (F : J ⥤ C), category_theory.limits.has_colimit F
C
has colimits of shape J
if we have chosen a particular colimit of
every functor F : J ⥤ C
.
Instances
- category_theory.limits.has_colimits_of_shape_of_has_colimits
- category_theory.limits.has_colimits_of_shape_of_has_finite_colimits
- category_theory.limits.has_colimits_of_shape_wide_pushout_shape
- category_theory.limits.has_colimits_of_shape_discrete
- category_theory.limits.functor_category_has_colimits_of_shape
- category_theory.over.has_colimits_of_shape
- has_colimits_of_shape : Π (J : Type ?) [𝒥 : category_theory.small_category J], category_theory.limits.has_colimits_of_shape J C
C
has all (small) colimits if it has colimits of every shape.
Instances
- category_theory.limits.has_colimits_of_complete_lattice
- category_theory.limits.types.category_theory.limits.has_colimits
- CommRing.colimits.has_colimits_CommRing
- AddCommGroup.colimits.has_colimits_AddCommGroup
- Mon.colimits.has_colimits_Mon
- category_theory.limits.functor_category_has_colimits
- category_theory.over.has_colimits
- category_theory.limits.category_theory.limits.has_colimits
- Top.Top_has_colimits
The chosen colimit cocone of a functor.
The chosen colimit object of a functor.
Equations
The coprojection from a value of the functor to the chosen colimit object.
Equations
Evidence that the chosen cocone is a colimit cocone.
The morphism from the chosen colimit object to the cone point of any other cocone.
Equations
We have lots of lemmas describing how to simplify colimit.ι F j ≫ _
,
and combined with colimit.ext
we rely on these lemmas for many calculations.
However, since category.assoc
is a @[simp]
lemma, often expressions are
right associated, and it's hard to apply these lemmas about colimit.ι
.
We thus use reassoc
to define additional @[simp]
lemmas, with an arbitrary extra morphism.
(see tactic/reassoc_axiom.lean
)
The cocone morphism from the chosen colimit cocone to any cocone.
The isomorphism (in Type
) between
morphisms from the colimit object to a specified object W
,
and cocones with cone point W
.
Equations
The isomorphism (in Type
) between
morphisms from the colimit object to a specified object W
,
and an explicit componentwise description of cocones with cone point W
.
Equations
If we've chosen a colimit for a functor F
,
we can transport that choice across a natural isomorphism.
Equations
- category_theory.limits.has_colimit_of_iso α = {cocone := (category_theory.limits.cocones.precompose α.hom).obj (category_theory.limits.colimit.cocone F), is_colimit := {desc := λ (s : category_theory.limits.cocone G), category_theory.limits.colimit.desc F ((category_theory.limits.cocones.precompose α.inv).obj s), fac' := _, uniq' := _}}
If a functor G
has the same collection of cocones as a functor F
which has a colimit, then G
also has a colimit.
Equations
- category_theory.limits.has_colimit.of_cocones_iso F G h = {cocone := category_theory.limits.is_colimit.of_nat_iso.colimit_cocone ((category_theory.limits.colimit.is_colimit F).nat_iso ≪≫ h), is_colimit := category_theory.limits.is_colimit.of_nat_iso ((category_theory.limits.colimit.is_colimit F).nat_iso ≪≫ h)}
The chosen colimits of F : J ⥤ C
and G : J ⥤ C
are isomorphic,
if the functors are naturally isomorphic.
The chosen colimits of F : J ⥤ C
and G : K ⥤ C
are isomorphic,
if there is an equivalence e : J ≌ K
making the triangle commute up to natural isomorphism.
The canonical morphism
from the chosen colimit of E ⋙ F
to the chosen colimit of F
.
Equations
- category_theory.limits.colimit.pre F E = category_theory.limits.colimit.desc (E ⋙ F) {X := category_theory.limits.colimit F _inst_4, ι := {app := λ (k : K), category_theory.limits.colimit.ι F (E.obj k), naturality' := _}}
The canonical morphism
from G
applied to the chosen colimit of F ⋙ G
to G
applied to the chosen colimit of F
.
Equations
- category_theory.limits.colimit.post F G = category_theory.limits.colimit.desc (F ⋙ G) {X := G.obj (category_theory.limits.colimit F), ι := {app := λ (j : J), G.map (category_theory.limits.colimit.ι F j), naturality' := _}}
If a E ⋙ F
has a chosen colimit, and E
is an equivalence, we can construct a chosen colimit of F
.
Functoriality of colimits.
Usually this morphism should be accessed through colim.map
,
but may be needed separately when you have specified colimits for the source and target functors,
but not necessarily for all functors of shape J
.
Equations
- category_theory.limits.colim_map α = category_theory.limits.colimit.desc F {X := category_theory.limits.colimit G _inst_5, ι := {app := λ (j : J), α.app j ≫ category_theory.limits.colimit.ι G j, naturality' := _}}
colimit F
is functorial in F
, when C
has all colimits of shape J
.
Equations
- category_theory.limits.colim = {obj := λ (F : J ⥤ C), category_theory.limits.colimit F, map := λ (F G : J ⥤ C) (α : F ⟶ G), category_theory.limits.colim_map α, map_id' := _, map_comp' := _}
The isomorphism between
morphisms from the cone point of the chosen colimit cocone for F
to W
and cocones over F
with cone point W
is natural in F
.
Equations
- category_theory.limits.colim_coyoneda = category_theory.nat_iso.of_components (λ (F : (J ⥤ C)ᵒᵖ), category_theory.nat_iso.of_components (category_theory.limits.colimit.hom_iso (opposite.unop F)) _) category_theory.limits.colim_coyoneda._proof_2
We can transport chosen colimits of shape J
along an equivalence J ≌ J'
.