Positive Region Deduction of Decision Table and Computation of Core

The problems of positive region reduction of decision table and computation of core were investigated so as to reduce the complexity of computation.The discernibility condition about decision objects was constructed,and the relationship between the positive region reduction and the set of discernibility attributes was discussed.A complete reduction method was proposed based on discernibility matrix and discernibility function.With this method,the positive region needs not to be calculated and the discernibility matrix can be constructed directly from the decision table.