proposition: Lemma mulmorDl (phi1 phi2 : 'Mor(M, N)) (psi : 'Mor(N, P)) : (phi1 + phi2) ** psi = phi1 ** psi + phi2 ** psi.
proof: Proof. by apply: val_inj => /=; rewrite mulmxDl. 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