inductive category (ob : Type) : Type := mk : Π (hom : ob → ob → Type) (comp : Π⦃a b c : ob⦄, hom b c → hom a b → hom a c), category ob inductive Category : Type := mk : Π (ob : Type), category ob → Category definition MK (a b c : Category) : _ := Category.mk a (category.mk b c)