“…The RST was introduced by Pawlak (1982Pawlak ( , 1991 as a useful tool to deal with data with uncertainty, reduce the size of data sets, find hidden patterns, and generate decision rules. Some recent applications on RST are medical cases (Ilczuk & Wakulicz-Deja, 2005;Wilk, 2005;Zaluski, Szoszkiewicz, Krysiń ski, & Stefanowski, 2004), business problems (Dimitras, Slowinski, Susmaga, & Zopounidis, 1999;Kumar & Agrawal, 2005;Shen & Loh, 2004), semiconductor manufacturing (Kusiak, 2001a(Kusiak, , 2001b. Komorowski, Pawlak, Polkowski, and Skowron (1999) provided a comprehensive tutorial and applications on rough sets; Pawlak (2004) proposed some recent research directions of rough sets.…”