fact: Definition dual_functor_involutive A B C (S : Functor A C) (T : Functor B C) : dual_functor S T o (dual_functor T^op S^op)^op = 1 /\ (dual_functor T^op S^op)^op o dual_functor S T = 1 := (idpath, idpath)%core.
imports: Category.Core Functor.Core Category.Dual Functor.Dual Functor.Composition.Core Functor.Identity