proposition: Lemma GE_prop7_rev E s: GT E s -> GL E s -> forall x, inc x E -> unit E s x -> GU E s.
proof: Proof. move => typ law x xE ue. move: (GE_prop2 typ law) => ll. exists x => // z zE. move:(ue z zE) => [ha hb]; split. rewrite - {2} ha; apply: (Law_in ll xE zE). rewrite - {2} hb; apply: (Law_in ll zE xE). Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)