proposition: Lemma le_wlength (ndf : {homo f : x y / (x <= y)%R}) : {homo wlength : A B / A `<=` B >-> A <= B}.
proof: Proof. move=> a b /le_Rhull /(le_wlength_itv ndf). by rewrite (wlength_Rhull a) (wlength_Rhull b). Qed.
imports: mathcomp(all_ssreflect ssralg ssrnum ssrint interval) mathcomp(finmap fingroup perm rat) HB(structures) mathcomp.classical(mathcomp_extra boolp classical_sets) mathcomp.classical(functions fsbigop cardinality) reals ereal signed topology numfun normedtype sequences esum real_interval measure realfun