fact: Definition is_kernel (M N K : {fpmod R}) (phi : 'Mor(M,N)) (k : 'Mor(K,M)) := ((k ** phi %= 0) * forall L (psi : 'Mor(L,M)), reflect (exists Y, Y ** k %= psi) (psi ** phi %= 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