缺省逻辑的e扩充和me扩充

E-EXTENSION AND ME-EXTENSION OF DEFAULT LOGIC

缺省逻辑（ＤｅｆａｕｌｔＬｏｇｉｃ）的扩充概念有二个弊端：１．无法描述缺省规则间固有的逻辑关系；２．无法描述结论与验证式之间的逻辑依赖关系．Ｗ．Ｌｕｋａｓｚｅｗｉｃｚ提出的ｍ扩充概念解决了问题２但没有解决问题１；本文首先提出了ｅ扩充的概念，它解决了问题１但没有解决问题２．最后我们提出了ｍｅ扩充的概念，解决了缺省逻辑遇到的两个问题，避免了相当一类的反常性．一个重要的结论是，每一封闭的缺省理论都有ｍｅ扩充．

The extension of Default logic can not express two questions: 1. the logic relationship between default rules; 2. the logic dependence between conclusion and its justifications. The e-extension proposed by lukaszewicz can only solve question 2,and the e-extension proposed in this paper can only solve the question 1.This paper also gives the me-extension concept,which can solve both questions. An important conclusion is that every closed default theory has a me-extension.