proposition: Lemma Rceil_ge0 x : 0 <= x -> 0 <= Rceil x.
proof: Proof. by move=> ?; rewrite -Rceil0 le_Rceil. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra) mathcomp(mathcomp_extra boolp classical_sets set_interval) Setoid