proposition: Lemma eqmorMl (psi : 'Mor(M, N)) (phi1 phi2 : 'Mor(N, P)) : phi1 %= phi2 -> psi ** phi1 %= psi ** phi2.
proof: Proof. by move=> phi12; rewrite /eqmor -mulmxBr dvdmxMl. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq path) mathcomp(ssralg fintype perm choice matrix bigop zmodp mxalgebra poly) ssrcomplements stronglydiscrete coherent edr