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Re: [ontolog-forum] OWL and lack of identifiers

To: "[ontolog-forum] " <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Ken Laskey <klaskey@xxxxxxxxx>
Date: Thu, 12 Apr 2007 16:29:14 -0400
Message-id: <A1D6187F-A59A-49FA-A8AD-8E08CB1BBF00@xxxxxxxxx>

I often questioned when talking about a URI that dereferenced to a Web page whether I was talking about
- the Web page (say, a collection of information on King Arthur),
- the subject of the Web page (i.e. King Arthur), or
- some particular piece of information (say, King Arthur had a sword named Excalibur)

A recent answer I got that made sense was that the domain and range of the properties used to describe the URI (i.e. the arcs in an RDF graph) provide the context to disambiguate the meaning.  While not considering that in detail, I think it works.

Does this start to address your problem?


On Apr 12, 2007, at 3:44 PM, Peter F Brown wrote:


Thanks for a fascinating overview. My comment on the webmeeting chat line was slightly facetious when I stated that: “If OWL added identifiers as you suggest, that would break Tim Berner-Lee's underlying model for Web architecture”, but I think that you hit the heart of one of the problems that I have with OWL and with the W3C axioms about information modelling: that is the failure to distinguish between:

-          a URL as an identifier of something, (in the terms you refer to in slide 34 [1]); and

-          a URL that is the “something” (a resource)

and the fact that you can’t actually make any assertion about a URL being considered as an identifier.


Although not designed as a standard for inferences and reasoning, the ISO Topic Maps standard does have an explicit mechanism for capturing and managing identity (using the concept of published subject identifiers), in the ways you describe are needed. I’m not sure what other specs out there do likewise, except for the humble URN…


In either case, we still have the problem of what you called “relative uniqueness” rather than, presumably, absolute uniqueness.


I look forward to seeing you at the Ontology Summit next week!





[1] http://ontolog.cim3.net/file/work/DatabaseAndOntology/2007-04-12_EdwardBarkmeyer/InfoModels-Ontologies--EdBarkmeyer_20070412.ppt



Peter F Brown

Founder, Pensive.eu

Chair, CEN eGovernment Focus Group

Co-Editor, OASIS SOA Reference Model

Lecturer at XML Summer School



+43 676 610 0250






Ken Laskey

MITRE Corporation, M/S H305     phone:  703-983-7934

7515 Colshire Drive                        fax:        703-983-1379

McLean VA 22102-7508

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