A COMPARATIVE-STUDY OF FUZZY-SETS AND ROUGH SETS

This paper reviews and compares theories of fuzzy sets and rough sets. Two approaches for the formulation of fuzzy sets are reviewed, one is based on many-valued logic and the other is based on modal logic. Two views of rough sets are presented, set-oriented view and operator-ori ented view. Rough sets under set-oriented view are closely related to fuzzy sets, which leads to non-truth-functional fuzzy set operators. B oth of them may be considered as deviations of classical set algebra. In contrast, rough sets under operator-oriented view are different fro m fuzzy sets, and may be regarded as an extension of classical set alg ebra. (C) 1998 Elsevier Science Inc. All rights reserved.