proposition: Lemma addr_Rgtb0 x y : Rltb 0 x -> Rltb 0 y -> Rltb 0 (x + y).
proof: Proof. by move/RltbP=> Hx /RltbP Hy; apply/RltbP/Rplus_lt_0_compat. Qed.
imports: Rdefinitions Raxioms RIneq Rbasic_fun Zwf Epsilon FunctionalExtensionality Ranalysis1 Rsqrt_def Rtrigo1 Reals mathcomp(all_ssreflect ssralg poly mxpoly ssrnum) HB(structures)