正规逻辑程序回答集存在性研究

判断逻辑程序的回答集是否存在是回答集程序设计的一个重要问题，也是NP完全问题。当前利用否定圈边数的奇偶性来判断回答集存在性的方法还具有一定的局限性，即:对于非分层逻辑程序，现有方法并不能准确判断其回答集存在性。针对该问题，提出了一种新的基于否定圈的判断方法，给出了该判断方法的算法框架，证明了算法的正确性，并以实例分析说明了方法的有效性。

Existence of Answer Sets of Normal Logic Programs

Determining the existence of answer sets of logic programs is a key problem in answer set programming, and is also NP-complete. Current methods for determining the existence of answer sets are mainly based on the evenness/oddness of the number of edges in negative circles.The limitation of this kind of methods is that if a normal logic program is not stratified, the existence of answer sets of the program cannot be accurately determined. A novel negative circle based method was proposed to solve this problem. An algorithmic framework and the correctness of the method were presented in this paper, and its effectiveness was illustrated by example analysis.