Colimits of external products #
External product with a fixed first diagram preserves colimits when tensoring with each value of that diagram does. Colimits in functor categories are computed pointwise, so the result follows by evaluating at a pair of objects. This supplies the colimit-preserving input to the left Kan extension defining Day convolution.
instance
CategoryTheory.MonoidalCategory.preservesColimitsOfShape_externalProductLeft
{C : Type u_1}
{C' : Type u_2}
{V : Type u_3}
{J : Type u_4}
[Category.{v_1, u_1} C]
[Category.{v_2, u_2} C']
[Category.{v_3, u_3} V]
[Category.{v_4, u_4} J]
[MonoidalCategory V]
(F : Functor C V)
[Limits.HasColimitsOfShape J V]
[∀ (x : C), Limits.PreservesColimitsOfShape J (tensorLeft (F.obj x))]
:
Limits.PreservesColimitsOfShape J (((externalProductBifunctorCurried C C' V).obj F).comp Functor.uncurry)
External product with a fixed first diagram preserves pointwise colimits if tensoring with each of its values does.