proposition: Lemma cast_intpartnKV m n eq_m_n : cancel (cast_intpartn (esym eq_m_n)) (@cast_intpartn m n eq_m_n).
proof: Proof. Proof using. by subst m. Qed.
imports: HB(structures) mathcomp(all_ssreflect) mathcomp(div ssralg ssrint ssrnum binomial) tools combclass sorted ordtype