proposition: Lemma validUnPtD k v f : valid (f \+ pts k v) -> k \notin dom f.
proof: Proof. by rewrite joinC; apply: validPtUnD. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)