Practical Prioritized Defaults via Logic Programs

We define courteous logic programs, a kind of prioritized default reasoning that is computationally tractable, fairly powerful expressively, and commercially applicable to the creation of rule-based intelligent information agents. Courteous programs permit classical negation in the head (consequent) or body (antecedent) of rules, in addition to permitting negation-as-failure in the body as in Prolog. Furthermore, courteous logic programs permit priorities betwe en rules mentioning the same predicate in their head. Conflict between rules is resolved using the priorities and a principle of skepticism, in a local fashion. As a result, courteous programs are guaranteed to have a unique, consistent set of conclusions. Courteous programs provide a method to resolve conflicts in authori ng (specifying), updating, merging, and advice-taking. Their prioritized default flavor enables a more common-sense style of specification, especially important for non-technical authors.

By: Benjamin N. Grosof

Published in: RC20464 in 1996


This Research Report is available. This report has been submitted for publication outside of IBM and will probably be copyrighted if accepted for publication. It has been issued as a Research Report for early dissemination of its contents. In view of the transfer of copyright to the outside publisher, its distribution outside of IBM prior to publication should be limited to peer communications and specific requests. After outside publication, requests should be filled only by reprints or legally obtained copies of the article (e.g., payment of royalties). I have read and understand this notice and am a member of the scientific community outside or inside of IBM seeking a single copy only.

Questions about this service can be mailed to .