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Knowledge acquisition in incomplete fuzzy information systems via the rough set approach
Author(s) -
Wu WeiZhi,
Zhang WenXiu,
Li HuaiZu
Publication year - 2003
Publication title -
expert systems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.365
H-Index - 38
eISSN - 1468-0394
pISSN - 0266-4720
DOI - 10.1111/1468-0394.00252
Subject(s) - computer science , fuzzy set operations , defuzzification , rough set , fuzzy classification , fuzzy number , type 2 fuzzy sets and systems , fuzzy logic , artificial intelligence , data mining , neuro fuzzy , complete information , fuzzy set , machine learning , mathematics , fuzzy control system , mathematical economics
Machine learning can extract desired knowledge from training examples and ease the development bottleneck in building expert systems. Most learning approaches derive rules from complete and incomplete data sets. If attribute values are known as possibility distributions on the domain of the attributes, the system is called an incomplete fuzzy information system. Learning from incomplete fuzzy data sets is usually more difficult than learning from complete data sets and incomplete data sets. In this paper, we deal with the problem of producing a set of certain and possible rules from incomplete fuzzy data sets based on rough sets. The notions of lower and upper generalized fuzzy rough approximations are introduced. By using the fuzzy rough upper approximation operator, we transform each fuzzy subset of the domain of every attribute in an incomplete fuzzy information system into a fuzzy subset of the universe, from which fuzzy similarity neighbourhoods of objects in the system are derived. The fuzzy lower and upper approximations for any subset of the universe are then calculated and the knowledge hidden in the information system is unravelled and expressed in the form of decision rules.