English
An equivalence of categories induces an additive structure on the inverse functor: the inverse functor is additive if F is fully faithful and the source category is equipped with the induced preadditive structure.
Русский
Эквивалентность категорий порождает аддитивность у обратного функторa, если исходная роль функторa F полностью точна и источник имеет индуцированную предаддитивную структуру.
LaTeX
$$$e^{-1}.Additive$$$
Lean4
/-- The preadditive structure on `C` induced by an equivalence `e : C ≌ D` makes `e.inverse` an
additive functor. -/
theorem additive_inverse_of_FullyFaithful (e : C ≌ D) :
letI : Preadditive C := ofFullyFaithful e.fullyFaithfulFunctor
e.inverse.Additive :=
letI : Preadditive C := ofFullyFaithful e.fullyFaithfulFunctor
letI : e.functor.Additive := e.fullyFaithfulFunctor.additive_ofFullyFaithful
e.inverse_additive