“…The IF set theory gives us the possibility to model hesitation and uncertainty by using an additional degree, i.e., the intuitionistic index. Over the last decades, the IF set theory has been applied to many different fields such as decision making (Atanassov, Pasi, and Yager, 2002;Herrera, Martinez, and Sanchez, 2005;Li, 2004Li, , 2005Kacprzyk, 2002, 2004), logic programming (Atanassov and Georgiev, 1993), topology (Abbas, 2005;Davvaz, Dudek, and Jun, 2006;Dudek, Davvaz, and Jun, 2005), medical diagnosis (De, Biswas, and Roy, 2001), pattern recognition (Li and Cheng, 2002;Wang and Xin, 2005) and machine learning as well as market prediction (Liang and Shi, 2003). In comparison with the fuzzy set, the IF set seems to be better suited for expressing a very important factor, i.e., the hesitation of the decision maker, which should be taken into account when we try to construct really adequate models and solutions of decision making problems.…”