摘要
本文在Reiter 1980年提出的缺省逻辑的基础上,将缺省条件视为获取知识的背景知识与所得到的知识同等地加以考虑,提出了一种缺省模态逻辑。它是一种非单调逻辑,并且具有在Reiter的系统中所不能保证的两个重要性质:扩充的存在性和非单调性,然后通过知识从其背景中分离出来的方法,给出了一个缺省理论扩充的概念,它是Reiter的扩充概念的一种推广。
On the logic for default reasoning proposed by Reiter in 1980, by taking the justification of a default rule as a background of acquiring knowledge with the acquired knowledge, and considering that they are the same, we suggest a formalism of nonmonotonic logic. We call it a modal logic for default reasoning since it contains a modality K. The new system has two important properties which are not guaranteed in Reiter's formalism: the existence of extensions and semimonotonicity. Then we suggest a new concept of extensions for default logic through separating the knowledge from their background. The concept is a natural generalization of Reiter's original proposal.
