proposition: Lemma DP_NH1_prop2 x: ~~ Dyck_NH1(DyckFT ++ x).
proof: Proof. by rewrite -(cat0s DyckFT); rewrite DP_NH1_prop1. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype) mathcomp(ssrnat seq path div) mathcomp(fintype tuple finfun bigop finset binomial)