Reiter的缺省逻辑的一个缺陷是不能分情形进行推理,为了克服Reiter扩充的这一缺陷,Roos提出了缺省扩充的一种修正定义来解决这一问题。文中将讨论Roos扩充类似于Reiter扩充的一些性质,发现Reiter扩充的一些性质对Roos扩充不再成立,并指出它们的不同。
One important defect of Reiter's default logic is inability to reason by cases,To overcome the defect definition of Reiter's extension.Roos presents a modified definition of a default extension that solves the problem,In this paper,we will discuss the properties of Roos-extension that are similar to Reiter-extension,and will find some properties of Reiter-extension can not still be correct to Roos-extension.We point out the difference of them.