【摘要】 不完全信息问题存在于每一种数据库模型中。传统的二值逻辑难以适应不完全信息处理的需求,而多值逻辑能更多地捕获不完全信息的直觉含义。在关系数据库系统的实现中,对不完全信息的处理通常采用三值逻辑。为满足实际应用的需要,本文选取了适用于不完全信息处理的一组联结词∧、∨、→、和μ作为构造逻辑系统的原始联结词。构造了一种新的三值逻辑命题演算系统M PM和三值逻辑谓词演算系统M FM,证明了其可靠性和完备性,并给出了在查询优化方面的应用。M FM可作为研究不完全信息数据库理论的逻辑基础。更多还原

【Abstract】 The problem of incomplete information exists in every kind of database model.The traditional two-valued logic is difficult to deal with incomplete information while the multi-valued logic can capture more intuitive meanings.When a relational database system is implemented,three-valued logic is usually adopted to handle incomplete information.To meet the application needs of the incomplete information database,based on original connectives ∧,∨,→, and μ,a new three-valued logic propositional calculus system MP~M and a new three-valued logic predicate calculus system MF~M are constructed.Furthermore,the soundness and the completeness of the MF~M are proved.Finally,its applications to query optimization are given.MF~M is regarded as a logical foundation for the theory of the incomplete information database.更多还原