“…More recently, rough set approximations have also been developed into the fuzzy environment, and the results are called rough fuzzy sets (fuzzy sets approximated by a crisp approximation space) [15,23,43,47,50] and fuzzy rough sets (fuzzy or crisp sets approximated by a fuzzy approximation space) [15,[26][27][28]30,36,46,48,50,58]. These models have been employed to handle fuzzy and quantitative data [17][18][19]21,40,45]. It can be observed that the constructive approach is suitable for practical applications of rough sets, and hence the majority of studies on rough sets have concentrated on the constructive approach.…”