Add Morphism radd with signature (req ==> req ==> req) as radd_ext2.Add Morphism rmul with signature (req ==> req ==> req) as rmul_ext2.Add Morphism ropp with signature (req ==> req) as ropp_ext2.

(* Specifications: *)
Lemma Rmul_0_l x : 0 * x == 0.
Lemma Ropp_mul_l x y : -(x * y) == -x * y.
Lemma Ropp_add x y : -(x + y) == -x + -y.
Lemma Ropp_opp x : - -x == x.
Lemma Rth_ARth : almost_ring_theory 0 1 radd rmul rsub ropp req.