fact: Definition decidable_embedding sT T (f : sT -> T) := forall y, decidable (exists x, y = f x).
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun ssrnat eqtype seq choice) mathcomp(div fintype path tuple bigop finset prime order) mathcomp(ssralg poly polydiv mxpoly countalg closed_field) mathcomp(ssrnum ssrint archimedean rat intdiv fingroup) mathcomp(finalg zmodp cyclic pgroup sylow vector falgebra) mathcomp(fieldext separable galois)