首选答案的简化推导
Warranted Derivations of Preferred Answer
摘要：
我们的目标是在语义的逻辑程序与规则上定义的偏好，它总是选择一个首选的答案集，如果有一个非空的一组（标准）答案集的给定程序。Brewka和Eiter在一篇开创性的论文中指出，上述目标与他们的第二个原则不相容，并且在优先级逻辑程序的语义中不满足。类似地，也根据其他建立的语义，基于规定性方法，存在具有标准答案集但没有优选答案集的程序。根据标准的规定性方法，没有规则可以在更优选的规则之前被触发，除非更优选的规则被阻塞。从其精神上讲，这是一种相当必要的做法。在我们的方法中，规则可以被更偏好的规则阻塞，但是未被阻塞的规则以更声明的方式处理，它们的执行不依赖于规则上给定的偏好关系。本文提出了一个不同于Dung的论证框架。Argu- mentation结构是从给定程序的规则中导出的。定义了论证结构上的攻击关系，该关系是由较偏好规则对较不偏好规则的攻击导出的。偏好答案集对应于完整的论证结构，其不被其他完整的论证结构阻挡。
英文摘要：
We are aiming at a semantics of logic programs with preferences defined on rules, which always selects a preferred answer set, if there is a non-empty set of (standard) answer sets of the given program. It is shown in a seminal paper by Brewka and Eiter that the goal mentioned above is incompatible with their second principle and it is not satisfied in their semantics of prioritized logic programs. Similarly, also according to other established semantics, based on a prescriptive approach, there are programs with standard answer sets, but without preferred answer sets. According to the standard prescriptive approach no rule can be fired before a more preferred rule, unless the more preferred rule is blocked. This is a rather imperative approach, in its spirit. In our approach, rules can be blocked by more preferred rules, but the rules which are not blocked are handled in a more declarative style, their execution does not depend on the given preference relation on the rules. An argumentation framework (different from the Dung's framework) is proposed in this paper. Argu- mentation structures are derived from the rules of a given program. An attack relation on argumentation structures is defined, which is derived from attacks of more preferred rules against the less preferred rules. Preferred answer sets correspond to complete argumentation structures, which are not blocked by other complete argumentation structures.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
