proposition: Lemma In_rangePt k : C k -> forall v x, x \In range (pts k v) <-> (x = v).
proof: Proof. move=>C' v x; rewrite In_rangeX. split. - by case=>w /InPt [[]]. by move=>->; exists k; apply: In_condPt. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)