Semanlink

We prove that entailment for RDFS (RDF Schema) is decidable, NP-complete, and in P if the target graph does not contain blank nodes.We show that the standard set of entailment rules for RDFS is incomplete and that this can be corrected by allowing blank nodes in predicate position. We define semantic extensions of RDFS that involve datatypes and a subset of the OWL vocabulary that includes the property-related vocabulary (e.g. Functional- Property), the comparisons (e.g. sameAs and differentFrom) and the value restrictions (e.g. allValuesFrom). These semantic extensions are in line with the 'if-semantics' of RDFS and weaker than the 'iff-semantics' of D-entailment and OWL (DL or Full). For these semantic extensions we present entailment rules, prove completeness results, prove that consistency is in P and that, just as for RDFS, entailment is NP-complete, and in P if the target graph does not contain blank nodes. There are no restrictions on use to obtain decidability: classes can be used as instances.

2007-02-06 A propos

On the properties of metamodeling in OWL

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Abstract: A common practice in conceptual modeling is to separate the intensional from the extensional model. Although very intuitive, this approach is inadequate for many complex domains, where the borderline between the two models is not clear-cut. Therefore, OWL-Full, the most expressive of the Semantic Web ontology languages, allows combining the intensional and the extensional model by a feature we refer to as metamodeling. In this paper, we show that the semantics of metamodeling adopted in OWL-Full leads to undecidability of basic inference problems, due to free mixing of logical and metalogical symbols. Based on this result, we propose two alternative semantics for metamodeling: the contextual and the HiLog semantics. We show that SHOIQ— a description logic underlying OWL-DL— extended with metamodeling under either semantics is decidable. Finally, we show how the latter semantics can be used in practice to axiomatize the logical interaction between concepts and metaconcepts.
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Eagle is a type of RedListSpecies. Thus, RedListSpecies acts as a
metaconcept for Eagle
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The examples such as the one given above are often dismissed with an argument that “eagle as a species” and “eagle as a set of all individual eagles”
are not the one and the same thing, and should not be referred to using the
same symbol...we simply observe that the word “eagle” in most people’s minds invokes a notion of a “mighty bird of prey.” The interpretation of
this notion as a concept or as an individual is secondary and is often context-dependent, so using different symbols for the same intuitive notion makes the
model unnecessarily complex.

2006-12-01 A propos

PR-OWL: A Bayesian Framework for the Semantic Web

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2006-11-07 A propos

PR-OWL: A Bayesian Ontology Language for the Semantic Web

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2006-09-07 A propos

UMBC eBiquity - Publications - Probabilistic Framework for Semantic Web - OWL and Bayesian Networks

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2006-05-01 A propos

alphaWorks : IBM Web Ontology Manager

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