Implicit Type a : pred T.

(* Specifications: *)
Lemma same_connect_rev : connect e =2 connect (fun x y => e y x).
Lemma connect_closed x : closed e (connect e x).
Lemma closure_closed a : closed e (closure e a).
Lemma mem_closure a : {subset a <= closure e a}.
Lemma n_comp_connect x : n_comp e (connect e x) = 1.