proposition: Lemma umfiltk_memdomE f : um_filterk (mem (dom f)) f = f.
proof: Proof. by apply/subdom_umfiltkE. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)