proposition: Lemma finite_der_Not : forall E, Finite (set_of_der E) -> Finite (set_of_der (Not E)).
proof: Proof. move => E hE. apply: (@Bar_gset_incl _ (pred_not (set_of_der E))). by apply: finite_pred_not. by apply: incl_der_pred_not. Qed.
imports: Coq(RelationClasses Setoid Morphisms Permutation) Coq(SetoidList Mergesort Orders) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq fintype) mathcomp(bigop path) RegLang(languages) RegexpBrzozowski(glue gfinset regexp)