proposition: Lemma hlength_singleton (r : R) : hlength `[r, r] = 0.
proof: Proof. rewrite /hlength /= 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) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(cardinality fsbigop) reals ereal signed topology numfun normedtype HB(structures) sequences esum measure real_interval realfun exp lebesgue_stieltjes_measure