🚀 go-pugleaf

           Department of Computer Science, University of Toronto
            (LP = D. L. Pratt Building, 6 King's College Road)

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                                    AI
               LP266, at 10:30 a.m., Monday 16 November 1992

                               Georg Gottlob
                   Technische Universitaet Wien, Austria

                            "CURB YOUR THEORY!
                 A CIRCUMSCRIPTIVE APPROACH FOR INCLUSIVE
                INTERPRETATION OF DISJUNCTIVE INFORMATION"

We introduce curbing, a new nonmonotonic technique of commonsense reasoning
that is based on model minimality but unlike circumscription treats
disjunction inclusively. A first-order theory T is transformed to a formula
CURB(T), called "the curb of T",  whose set of models consists of  the
smallest collection of models which contains all minimal models of T and
which is closed under formation of minimal upper bounds with respect to
model-inclusion.

We first give a rather intuitive definition of CURB in third-order logic
and then show how CURB can be equivalently expressed in second-order logic.
We study the complexity of inferencing from a curbed theory in the
propositional case and present a PSPACE algorithm for this problem.  We
address different possibilities to approximate the curb of a theory.
Finally, we compare the curbing method to other approaches to inclusive
interpretation of disjunctive information.

This talk reports on joint work with Thomas Eiter (TU Vienna, Austria) and
Yuri Gurevich (U. Ann Arbor, Michigan and INRIA, France).