fact: Definition is_coker (M N C : {fpmod R}) (phi : 'Mor(M,N)) (c : 'Mor(N,C)) := ((phi ** c %= 0) * forall L (psi : 'Mor(N,L)), reflect (exists Y, c ** Y %= psi) (phi ** psi %= 0))%type.
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