FUZZY SETS AND SYSTEMS, cilt.110, sa.2, ss.275-278, 2000 (SCI-Expanded)
For a crisp and non-empty set X, nth-order genuine sets in X and the set-theoretic operations of equality, inclusion, complement, intersection and union among the nth-order genuine sets in X are introduced in [1]. In this paper, it is shown that one needs a natural assumption and some conditions restricting the selection of operations equality, inclusion, complement, intersection and union defined on the nth-order genuine set in X to present the nth-order genuine sets in X as an extension of the mth-order genuine sets in X (m less than or equal to n). (C) 2000 Elsevier Science B.V. All rights reserved.