David Poole's Specificity Revised

David Poole (1985) has sketched such a notion as a binary relation on arguments and evaluated its intuitive validity with some examples. Poole’s notion of specificity was given a more appropriate formalization in (Simari and Loui 1992). The properties of this formalization were examined in detail in (Stolzenburg et al. 2003). In the middle of the 1980s, David Poole introduced a semantical, model-theoretic notion of specificity to the artificialintelligence community. Since then it has found further applications in non-monotonic reasoning, in particular in defeasible reasoning. Poole’s notion, however, turns out to be intricate and problematic, which — as we show — can be overcome to some extent by a closer approximation of the intuitive human concept of specificity. Besides the intuitive advantages of our novel specificity ordering over Poole’s specificity relation in the classical examples of the literature, we also report some hard mathematical facts: Contrary to what was claimed before, we show that Poole’s relation is not transitive. Our new notion of specificity is transitive and also monotonic w. r. t. conjunction.

Authors

• Claus-Peter Wirth
• Frieder Stolzenburg

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