proposition: Lemma wlength_singleton (r : R) : wlength `[r, r] = 0.
proof: Proof. rewrite /wlength /= asboolT// sup_itvcc//= asboolT//. by rewrite asboolT inf_itvcc//= ?subee// inE. 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