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
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