Section Modular.
Variables A X: Type.
Variable TX: reduction_t A X.
Let F  := Comp (chaining_l (expand TX TX)) (chaining_r (bisim TX TX)).
Let G  := Comp (star (X:=X)) (Union2 (identity (X:=X) (Y:=X)) (constant (bisim TX TX))).

Lemma G_reverse: forall R, eeq (trans (G R)) (G (trans R)).