proposition: Lemma w_gt0 : 0 < w.
proof: Proof. by rewrite w_val divr_gt0 // rat_of_Z_Zpos. Qed.
imports: ZArith mathcomp(all_ssreflect all_algebra all_field) extra_mathcomp tactics binomialz floor arithmetics posnum rat_of_Z hanson_elem_arith hanson_elem_analysis