fact: Definition epimorphism phi MkEpi : epimorphism_of := MkEpi (let: Epimorphism _ phi_epi := phi return surjm phi in phi_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