@Book{Wirth_Stolzenburg_Specifity_2013,
year={2013},
author={Wirth, Claus-Peter
    and Stolzenburg, Frieder},
title={David Poole's Specifity Revised},
publisher={{SEKI Publications}},
series={{SEKI-Report SR--2013--01 (ISSN 1437--4447)}},
address={{DFKI Bremen GmbH, Safe and Secure Cognitive Systems, Cartesium, Enrique Schmidt Str.\,5, D--28359 Bremen, Germany}},
note={pp.\,ii+22, \url{http://arxiv.org/abs/1308.4943}},
abstract={In the middle of the 1980s, David Poole introduced a semantical, model-theoretic notion of specifity to the artificial-intelligence community. Since then it has found further applications in non-monotonic reasoning, in particular in defeasible reasoning. Poole tried to approximate the intuitive human concept of specifity, which seems to be essential for reasoning in everyday life with its partial and inconsistent information. His 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 specifity. Besides the obvious intuitive advantages of our new specifity ordering over Poole's specifity relation in the classical examples of the literature, we also report some hard mathematical facts: Contrary to what was claimed to be proved before, we show that Poole's relation is not transitive. Moreover, the top-down (SLD-style) computation of activation sets as one means to decide the specifity relations is straightforward for our new specifity ordering and does not show the previously reported complications of Poole's relation. Keywords: Specifity, Logic Programming, Defeasible Reasoning, Non-Monotonic Reasoning},
}