proposition: Lemma Rfloor_lt0 x : x < 0 -> Rfloor x < 0.
proof: Proof. by move=> x0; rewrite (le_lt_trans _ x0) // Rfloor_le. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra) mathcomp(mathcomp_extra boolp classical_sets set_interval) Setoid