Similarity preservation in default logic

The paper identifies a problem in default reasoning in Reiter’s Default Logic and related systems: elements which are similar given the axioms only, become distinguishable in extensions. We explain why, sometimes, this is considered undesirable. Two approaches are presented for guaranteeing similari...

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Bibliographic Details
Published in:Annals of mathematics and artificial intelligence 1999-01, Vol.25 (1-2), p.137-160
Main Authors: Ben-Eliyahu-Zohary, Rachel, Francez, Nissim, Kaminski, Michael
Format: Article
Language:English
Subjects:
Axioms
Similarity
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Summary:The paper identifies a problem in default reasoning in Reiter’s Default Logic and related systems: elements which are similar given the axioms only, become distinguishable in extensions. We explain why, sometimes, this is considered undesirable. Two approaches are presented for guaranteeing similarity preservation: One approach formalizes a way of uniformly applying the defaults to all similar elements by introducing generic extensions, which depend only on similarity types of objects. According to the second approach, for a restricted class of default theories, a default theory is viewed as a “shorthand notation” to what is “really meant” by its formulation. In this approach we propose a rewriting of defaults in a form that guarantees similarity preservation of the modified theory. It turns out that the above two approaches yield the same result.
ISSN:1012-2443
1573-7470
DOI:10.1023/A:1018921920657