proposition: Lemma fmvalK : cancel val fmod.
proof: Proof. by case=> x Ax; apply: val_inj; rewrite /fmod /= sgvalK. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq path) mathcomp(div choice fintype bigop ssralg finset fingroup) mathcomp(morphism perm finalg action gproduct commutator) mathcomp(cyclic)