proposition: Lemma ltrD2r x : {mono +%R^~ x : y z / y < z}.
proof: Proof. by move=> y z /=; rewrite (leW_mono (lerD2r _)). Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)