Letf:X→Ya function,Ra relation defined byR⊂X×X×XandSa partial order inx. To each relationRthere exists anR-system consisting of subsets ofXwith an selected subsetX0. Iffpossesses the property of (R,S)-maximality the set ofS-maxima off(X) is equal to the set ofS-maxima off(X0. If possesses the property of (R,S)-minimality the set ofS-minima off(X) is equal to the set ofS-minima off(X0).