@article {74,
	title = {Local Closed World Reasoning with Description Logics under the Well-Founded Semantics},
	journal = {Artificial Intelligence},
	volume = {175},
	year = {2011},
	pages = {1528{\textendash}1554},
	abstract = {<p class="rtejustify">An important question for the upcoming Semantic Web is how to best combine open world ontology languages, such as the OWL-based ones, with closed world rule-based languages. One of the most mature proposals for this combination is known as hybrid MKNF knowledge bases [52], and it is based on an adaptation of the Stable Model Semantics to knowledge bases consisting of ontology axioms and rules. In this paper we propose a well-founded semantics for nondisjunctive hybrid MKNF knowledge bases that promises to provide better efficiency of reasoning, and that is compatible with both the OWL-based semantics and the traditional Well-Founded Semantics for logic programs. Moreover, our proposal allows for the detection of inconsistencies, possibly occurring in tightly integrated ontology axioms and rules, with only little additional effort. We also identify tractable fragments of the resulting language.</p>
},
	keywords = {Description Logic, Knowledge representation, Logic Programming, Non-monotonic reasoning, Ontologies, Semantic Web},
	doi = {10.1016/j.artint.2011.01.007},
	url = {http://dx.doi.org/10.1016/j.artint.2011.01.007},
	author = {Matthias Knorr and Jos{\'e} J{\'u}lio Alferes and Pascal Hitzler}
}
@article {82,
	title = {Generalized Distance Functions in the Theory of Computation},
	journal = {Computer Journal},
	volume = {53},
	year = {2010},
	pages = {443{\textendash}464},
	abstract = {<p class="rtejustify">We discuss a number of distance functions encountered in the theory of computation, including metrics, ultra-metrics, quasi-metrics, generalized ultra-metrics, partial metrics, d-ultra-metrics and generalized metrics. We consider their properties, associated fixed-point theorems and some general applications they have within the theory of computation. We consider in detail the applications of generalized distance functions in giving a uniform treatment of several important semantics for logic programs, including acceptable programs and natural generalizations of them, and also the supported model and the stable model in the context of locally stratified extended disjunctive logic programs and databases.</p>
},
	keywords = {denotational semantics, fixed-point theorems, generalized distance functions, Logic Programming, stable model, supported model, topology, ultra-metrics},
	doi = {10.1093/comjnl/bxm108},
	url = {http://dx.doi.org/10.1093/comjnl/bxm108},
	author = {Anthony K. Seda and Pascal Hitzler}
}
