proposition: Lemma sorted_dom_oleq f : sorted (@oleq K) (dom f).
proof: Proof. by apply: sorted_oleq (sorted_dom f). Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)