Monday, September 19, 2005

Lack of Symmetry

Catching up on Journal of Web Semantics: Preprint Server:
* Completeness, decidability and complexity of entailment for RDF Schema and a semantic extension involving the OWL vocabulary "RDFS entailment is decidable, NP-complete, and in P if the target graph does not contain blank nodes...In this paper we extend the notion of RDF graph to allow blank nodes in predicate position and show that the standard entailment rules for RDFS become complete if rule rdfs7 is replaced by a suitably extended rule rdfs7x. In view of the fact that the semantics of RDFS allows blank nodes to refer to properties, ‘generalized RDF graphs’, which allow blank nodes in predicate position, seem to form a more direct abstract syntax for RDFS than RDF graphs."
* OWL-Eu: Adding Customised Datatypes into OWL "1. OWL does not support customised datatypes (except enumerated datatypes)...
2. OWL does not support negated datatypes. For example, ‘all integers but 0’...
3. An OWL DL datatype domain seriously restricts the interpretations of typed literals with unsupported datatype URIrefs..."

"OWL-Eu supports customised datatypes through unary datatype expressions based on unary datatype groups. Intuitively, an unary datatype group extends the OWL datatyping with a hierarchy of supported datatypes."
Post a Comment