For Logical System Of Information Database Research

Incomplete information database is an .important field in database theory. It has important theoretical and practical values. The Medium Logic Propositional Calculus System MPM and the Medium Logic Predicate Calculus System MFM are new logic systems. They are fit for dealing with incomplete information. This paper discusses the system MPM and MFM, constructs the normal form theories of MPM and its tableau system. The soundness and completeness theorem of the tableau system are also given. The normal form theories can keep the intuition relationship between the Complete Normal Form and the Truth Table, which only keeps in classical 2-valued logic system. The tableau system can act as the automated reasoning system in incomplete information environments. In addition, by introducing three operators, judging true, judging medium and judging false, the relationship between the system MF and the classical 2-valued logic system is discussed. Based on the relationship, the resolution principles of MFM are given by taking the classical 2-valued logic system as a tool. The resolution principles show that the resolution problems can be solved by using the theories of the classical 2-valued logic system.