proposition: Lemma ssim1_congr_Plus : forall a b c d, ssim1 a b -> ssim1 c d -> ssim1 (Plus a c) (Plus b d).
proof: Proof. rewrite /ssim1 => a b c d; case/andP => h1 h2; case/andP => h3 h4. rewrite ssublPlus2 ssubrPlus2. rewrite ssublPlusl => //. rewrite ssublPlusr => //. rewrite ssubrPlusl => //. by rewrite ssubrPlusr. 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)