Isomorphisms about functors which preserve (co)limits #
If G
preserves limits, and C
and D
have limits, then for any diagram F : J ⥤ C
we have a
canonical isomorphism preservesLimitsIso : G.obj (Limit F) ≅ Limit (F ⋙ G)
.
We also show that we can commute IsLimit.lift
of a preserved limit with Functor.mapCone
:
(PreservesLimit.preserves t).lift (G.mapCone c₂) = G.map (t.lift c₂)
.
The duals of these are also given. For functors which preserve (co)limits of specific shapes, see
preserves/shapes.lean
.
If G
preserves limits, we have an isomorphism from the image of the limit of a functor F
to the limit of the functor F ⋙ G
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Alias of CategoryTheory.preservesLimitIso_hom_π
.
Alias of CategoryTheory.preservesLimitIso_inv_π
.
If C, D
has all limits of shape J
, and G
preserves them, then preservesLimitsIso
is
functorial wrt F
.
Equations
- CategoryTheory.preservesLimitNatIso G = CategoryTheory.NatIso.ofComponents (fun (F : CategoryTheory.Functor J C) => CategoryTheory.preservesLimitIso G F) ⋯
Instances For
If the comparison morphism G.obj (limit F) ⟶ limit (F ⋙ G)
is an isomorphism, then G
preserves limits of F
.
If G
preserves colimits, we have an isomorphism from the image of the colimit of a functor F
to the colimit of the functor F ⋙ G
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Alias of CategoryTheory.ι_preservesColimitIso_inv
.
Alias of CategoryTheory.ι_preservesColimitIso_hom
.
If C, D
has all colimits of shape J
, and G
preserves them, then preservesColimitIso
is functorial wrt F
.
Equations
Instances For
If the comparison morphism colimit (F ⋙ G) ⟶ G.obj (colimit F)
is an isomorphism, then G
preserves colimits of F
.