Section Lemmas.
Variable R : RING.
exact (sgroup_assoc_prf (E:=R) (ring_monoid R)).
Qed.
unfold ring_mult in |- *; auto with algebra.
Qed.
exact (monoid_unit_r_prf (ring_monoid R)).
Qed.

Lemma RING_unit_l : forall x : R, Equal (ring_mult (ring_unit R) x) x.