fact: Definition wlength (A : set (ocitv_type R)) : \bar R := let i := Rhull A in g i.2 - g i.1.
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