(* fracions form an abelian group *)
Canonical frac_zmodType := Eval hnf in ZmodType type frac_zmodMixin.

(* Specifications: *)
Lemma mulA : associative mul.
Lemma mulC : commutative mul.
Lemma mul1_l : left_id 1%:F mul.
Lemma mul_addl : left_distributive mul add.
Lemma nonzero1 : 1%:F != 0%:F :> type.
Lemma inv0 : inv 0%:F = 0%:F.
Definition RatFieldUnitMixin := FieldUnitMixin mulV_l inv0.