fact: Record epimorphism_of := Epimorphism { morphism_of_epi :> 'Mor(M, N); _ : surjm morphism_of_epi }.
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