# Tech Report CS-90-08

## A Preference-Based Approach to Inheritance

### Abstract:

Existing theories of nonmonotonic inheritance are generally either computationally feasible or semantically well-founded, but not both. We present four approaches to inheritance reasoning: \begin{itemize} \item a Touretzky-style path-based theory \item a model-theoretic semantics \item a polynomial-time inference algorithm \item a reason-maintenance labeling scheme \end{itemize} and demonstrate that these four approaches yield equivalent results. The underlying framework further provides a unified theory of inheritance suitable for principled analysis of existing inheritance systems (rather than {\em ad hoc} comparison on specific examples).

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