Computation Of Approximations And Attributes Reduction Of Decision Table Based On Pansystems Theory

In the rough set theory and rough-fuzzy set theory, computation of approximations and edge and attributes reduction of decision table is import part of them. Any set and binary relation can be presented by a mapping from the point of body-shadow relation of pansystems, we introduce the body-shadow relation of pansystems to the comptution and draw some conclusions, and now list them as follows:l.This paper presents a unified formula of solving the lower approximate and the upper approximate of rough set and rough-fuzzy set, and proves that the formula is equivalent to the traditional one. We conclude that the upper and lower approximation and the edge of rough sets are consistent with that of rough fuzzy sets, that of rough fuzzy sets are consistent with that of fuzzy rough sets, that is to say, the former is the extreme of pansystems of the latter.At the same time, I present the rough-fuzzy binary relation and the fuzzy-rough binary relation. The rough set theory is extended by the conclusion.2. I present the ascertainment degree of decision rules based on the generalized inclusion of set. Furthermore, P-compatible decision table is put forward, all the ascertainment degree of decision rules of which are greater than β.Here β is called confidence level by people. The traditional concept of decision table is extended for compatible decision table is the decision table whose β is 1, so the rough set theory is extended. The concept of P-compatible decision table can be the theoretical bases on which people can be based when they put forward some truthful arithmetic.3.To reduce the attributes and compute the kernel of P-compatible decision table, I expand the traditional definition of redundant attributes. In this paper, when an attribute of a p-compatible decision table is removed ,but the degree of compatibility of it dose not change smaller, we call the attribute a redundant one. I reduce the attributes and compute the kernel of P-compatible decision table through the modified attributes reduction algorithm which based on the degree of inclusion.