The Research Of Algorithm For Computing Extension Of Assumption In Propositional Logic And Its Application

Achieving common sense reasoning as a long-term goal of artificial intelligence research can be loosely traced to the birth of Artificial Intelligence. In daily life, common sense reasoning can help us in the case of incomplete information to make valid inferences, according to make a reasonable assumption. Currently, belief revision, one of the methods that handling the nonmonotonic problem in common sense reasoning, has been widely studied. This approach adjusted the information into the existing knowledge base by introducing a revison operator. However, some expected information may be losted during the revison process. Unlike belief revision methods, belief non-revision method can get consistent extension by limiting the reasoning process without changing the knowledge base, achieving effective reasoning.In propositional logic, the extension of the assumption has been proven to possessing of several valuable properties. According to the current study, the extension of an assumption consists of a finite clause would be an infinite set. In order to applying the non-revision method in practical way easily, this paper makes the following research:(1) The extension of assumption in propositional logic is defined. This definition makes the extension of the assumption that consist of a limited number of clause remains a finite set and hold that it is logically equivalence with the existing extension. And this property is proved.(2) The algorithm for computing extension of a given assumption is designed. The algorithm is based on the algorithm for computing prime implicates of a clause, and it is proved to be correct. Then the algorithm is implemented with JAVA language. The experiment takes multiple assumptions as test cases and verfied that the algorithm is correct and reliable.(3) The extension of assumption in propositional logic is used as knowledge compilation target language. Knowledge compliation is the basis for knowledge representation and reasoning, having a wide range of applications. So this paper proposes a knowledge compliation method based on the extension of assumption as we have defined. Then this paper analyses the relationship between knowledge compliation method based on the extension of assumption with other methods.