proposition: Lemma umallb_undef p : um_allb p undef.
proof: Proof. by rewrite /um_allb umcnt_undef dom_undef. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)