proposition: Lemma linv_surj (psi : 'Mor(N, M)) : psi ** phi %= idm -> coker phi %= 0.
proof: Proof. move/(eqmorMr (coker phi)); rewrite -mulmorA mul1mor. by rewrite (eqmor_ltrans (eqmorMl _ (mulmorc _))) mulmor0 eqmor_sym. 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