Riemann had sought to extend this extremely useful property to sets E of functions of real variables, but it soon appeared that boundedness of E was not sufficient.
Riemann had sought para i-extend ito balisang-kapaki-pakinabang na ari-arian sa set ng E ng mga pag-andar ng mga tunay na variable, ngunit ito sa lalong madaling panahon ay lumitaw na boundedness ng E ay hindi sapat.