Re: Coordination with RDF Core

From: Frank van Harmelen (
Date: 07/10/01

Below a proposed addition on the "syntax and semantics of URIs".


Syntax and semantics of URLs

Although there is a syntax for a general URIs, there does not appear to
be a good specification for the URIs that appear in RDF documents, in
particular, how URIs are composed in the presence of
namespaces and RDF ``fragments'', including whether namespaces are
permissable in URIs that are not XML URIs.  There has been considerable RDF
debate on these points.

 - Does the set of URL's have a non-trivial structure?
   o Can two syntactically-different URIs point to the same domain element?
   o can the same URI string name a different resource at different times?
   o Can a URI (sometimes) fail to refer
FvH: in general, they can. In DAML+OIL, two URI's are different
     unless declared to be equivalent. 

- It seems reasonable to interpret URI's as logical constants. This
  raises that question what the total universe of discourse is to
  interpret DAML+OIL.
  One possibility is to take the set AD from the denotational
  semantics as consisting of exactly the URIs appearing in a given piece
  of DAML+OIL. This would be the DAML+OIL equivalent of a Herbrand
  interpretation. But it remains unclear what the universe of
  discourse is in general.

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