proposition: Lemma plus_0_l: forall x, 0%Qnn + x == x.
proof: Proof. refine (binop_unit_left Qplus 0 (Qle_refl _) QnonNeg.Qplus_nonneg _ Qplus_0_l). intros. apply Qplus_le_compat; intuition. Qed.
imports: Coq.QArith.Qabs CoRN.model.ordfields.Qordfield CoRN.model.structures.Qpossec Coq.QArith.Qminmax Coq.setoid_ring.Ring Coq.Program.Program