NEIGHBORHOOD SYSTEMS AND DECISION MAKING

(1) Improve some of different approximations.(2) Generalize these approximations by different ways.(3) Make a comparison between all results and give the best approximation.We introduce a new method for approximation of sets byusing a finite number of information systems. Some fundamental properties and characterizations are given and we obtain a comparison between this type of approximations and Pawlak’s approximations. Also, we use Pawlak’s definitions and Yao’s definitions f