English
Each shift functor by an integer is additive on the Homotopy category: for every integer n, the functor shift by n preserves addition of morphisms.
Русский
Для каждого целого n сдвиговой функтор по gомотопической категории сохраняет сложение морфизмов (является аддитивным).
LaTeX
$$$\\forall n \\in \\mathbb{Z},\\; (\\mathrm{shiftFunctor} (\\mathrm{HomotopyCategory} (C, \\mathrm{ComplexShape.up} \\mathbb{Z}))\\; n).\\mathrm{Additive}$$$
Lean4
instance (n : ℤ) : (shiftFunctor (HomotopyCategory C (ComplexShape.up ℤ)) n).Additive :=
by
have : ((quotient C (ComplexShape.up ℤ) ⋙ shiftFunctor _ n)).Additive :=
Functor.additive_of_iso ((quotient C (ComplexShape.up ℤ)).commShiftIso n)
apply Functor.additive_of_full_essSurj_comp (quotient _ _)