proposition: Lemma domeq2_refl (f : U1) : dom_eq2 f f.
proof: Proof. by rewrite /dom_eq2 !eqxx. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)