Lean4
/-- The obvious isomorphism between
`HomotopyCategory.quotient V c ⋙ F.mapHomotopyCategory c` and
`F.mapHomologicalComplex c ⋙ HomotopyCategory.quotient W c` when `F : V ⥤ W` is
an additive functor. -/
def mapHomotopyCategoryFactors (F : V ⥤ W) [F.Additive] (c : ComplexShape ι) :
HomotopyCategory.quotient V c ⋙ F.mapHomotopyCategory c ≅
F.mapHomologicalComplex c ⋙ HomotopyCategory.quotient W c :=
CategoryTheory.Quotient.lift.isLift _ _
_
-- TODO `F.mapHomotopyCategory c` is additive (and linear when `F` is linear).
-- TODO develop lifting of natural transformations for general quotient categories so that
-- `NatTrans.mapHomotopyCategory` become a particular case of it