The results in this chapter are based mostly on the works in Akram (Inf Sci, 181:5548–5564, 2011) , Akram and Dudek (Comput Math Appl, 61(2):289–299, 2011) , Akram et al. (J Appl Math, 2013, 2013) , Akram et al. (Afr math, 2014) . In 1975, Zadeh (Inf Sci, 8:199–249, 1975)  introduced the notion of interval-valued fuzzy sets as an extension of fuzzy sets (Zadeh, Inf Control, 8:338–353, 1965, ) in which the values of the memberships degrees are intervals in [0, 1] instead of elements in [0, 1]. Interval-valued fuzzy sets provide a more adequate description of uncertainty than traditional fuzzy sets in some cases. It can therefore be important to use interval-valued fuzzy sets in applications, e.g., in fuzzy control.