proposition: Lemma size_DP_raise l: size (DP_raise l) = (size l).+2.
proof: Proof. by rewrite /DP_raise /= size_rcons. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype) mathcomp(ssrnat seq path div) mathcomp(fintype tuple finfun bigop finset binomial)