proposition: Lemma ssublDot_ok : forall b, ssubl (Dot char) b -> forall x, (x \in (Dot char) ) -> (x \in b).
proof: Proof. elim => //. move => r1 hr1 r2 hr2. rewrite ssublPlus1 //. case/orP => hu x. - rewrite -!topredE /= => hx. apply/orP; left. by apply: hr1. rewrite -!topredE /= => hx. apply/orP; right. by apply: hr2. Qed.
imports: Coq(RelationClasses Setoid Morphisms Permutation) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq fintype) mathcomp(bigop path) RegLang(languages) RegexpBrzozowski(regexp finite_der equiv)