{A B C A' B' C'} (f : A -> A') (g : B -> B') (h : C -> C') : trijoin_twist A' B' C' o functor_join f (functor_join g h) == functor_join g (functor_join f h) o trijoin_twist A B C. Proof. intro x. lhs nrefine (ap _ (functor_trijoin_as_functor_join f g h x)). rhs nrapply functor_trijoin_as_functor_join. apply '. Defined.
Require Import Basics Types WildCat Join.Core Join.TriJoin Spaces.Nat.Core.