proposition: Lemma defE f : defined f = UM.valid (from f).
proof: Proof. by case: U f=>x [*]. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)