proposition: Lemma mul_lift (M N L : {fpmod R}) (phi : 'Mor(M,N)) (psi : 'Mor(N,L)) : phi ** psi %= 0 -> coker phi ** lift phi psi %= psi.
proof: Proof. rewrite /lift; case: eqP => //= p _. by rewrite /eqmor /= mul1mx subrr. 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