category.equivalence.to._Fun : Π {C : category.Precategory} {D : category.Precategory} (c : category.equivalence C D) {a b : category.Precategory.carrier C}, category.hom a b → category.hom (functor.to_fun_ob (category.equivalence.to_functor c) a) (functor.to_fun_ob (category.equivalence.to_functor c) b)