proposition: Lemma um0UndefE : ((Unit : union_mapPCM K V) == undef) = false.
proof: Proof. by rewrite eq_sym umUndef0E. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)