“…Rough set theory becomes an indispensable tool in the field of data mining. It develops quickly in a short time after being founded, at present, it has been used widely in the fields, such as: expert system, artificial intelligence, decision support system, knowledge discovery (data mining), pattern recognition and medical diagnostics [2], etc. It is complementary to the probability theory, the fuzzy theory, the evidence theory and other theories of processing uncertain and imprecise problems.…”