A terminologal default logic.
In European research consortium for informatics and
mathematics workshop on theoretical and experimental aspects of knowledge representation,
Pisa, PI, 1992.
Terminological Logics are knowledge representation formalisms of considerable
applicative interest, as they are specifically oriented to the vast class of application
domains that are describable by means of taxonomic organizations of complex objects.
Although the field of terminological logics has lately been an active area of investigation,
few researchers (if any) have addressed the problem of extending these logics with
the ability to perform default reasoning. Such extensions would prove of paramount
applicative value, as for many application domains a formalization by means of monotonic
terminological logics may be accomplished only at the price of oversimplification.
In this paper we show how we can effectively integrate terminological reasoning and
default reasoning, yielding a terminological default logic. The kind of default
reasoning we embed in our terminological logic is reminiscent of Reiter's Default
Logic, but overcomes some of its drawbacks by subscribing to the ``implicit"
handling of exceptions typical of the Multiple Inheritance Networks with Exceptions
proposed by Touretzky and others.