Logic Programs with Compiled Preferences

TL;DR

This paper presents a method to compile preferences into logic programs under answer set semantics, enabling the use of existing systems like dlv and smodels to compute preferred answer sets.

Contribution

It introduces a general methodology for incorporating static and rule-set preferences into logic programs through a compilation approach, compatible with existing answer set solvers.

Findings

The approach correctly respects preferences in answer sets.

The compilation enables use of existing logic programming tools.

The method supports both static and rule-set preferences.

Abstract

We describe an approach for compiling preferences into logic programs under the answer set semantics. An ordered logic program is an extended logic program in which rules are named by unique terms, and in which preferences among rules are given by a set of dedicated atoms. An ordered logic program is transformed into a second, regular, extended logic program wherein the preferences are respected, in that the answer sets obtained in the transformed theory correspond with the preferred answer sets of the original theory. Our approach allows both the specification of static orderings (as found in most previous work), in which preferences are external to a logic program, as well as orderings on sets of rules. In large part then, we are interested in describing a general methodology for uniformly incorporating preference information in a logic program. Since the result of our translation is an extended logic program, we can make use of existing implementations, such as dlv and smodels. To this end, we have developed a compiler, available on the web, as a front-end for these programming systems.