proposition: Lemma umPtUndefE (k : K) (v : V) : (k \\-> v == undef) = false.
proof: Proof. by rewrite /eq_op /undef /= /UnionMapEq.unionmap_eq /um_pts !umEX. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)