proposition: Lemma ceil_ge_int x (z : int) : (x <= z%:~R) = (ceil x <= z).
proof: Proof. by rewrite /ceil lerNl -floor_ge_int// -lerNr mulrNz opprK. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra) mathcomp(mathcomp_extra boolp classical_sets set_interval) Setoid