proposition: Lemma Set_of_der_compat1 : forall E, E_compat sim (set_of_der E).
proof: Proof. rewrite /E_compat. by apply : set_of_der_compat. Qed.
imports: Coq(RelationClasses) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq fintype) mathcomp(bigop path) RegLang(languages) RegexpBrzozowski(glue gfinset regexp finite_der)