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RE: OWL : Taxonomies VS. the semantic web a mismatch?

From: <Patrick.Stickler@nokia.com>
Date: Tue, 9 Sep 2003 09:28:30 +0300
Message-ID: <A03E60B17132A84F9B4BB5EEDE57957B026302DC@trebe006.europe.nokia.com>
To: <mortench2003@yahoo.dk>, <www-rdf-interest@w3.org>
Cc: <Patrick.Stickler@nokia.com>
Would you be able to present a few examples of these apparently conflicting cases?

-----Original Message-----
From: ext Morten Christensen [mailto:mortench2003@yahoo.dk]
Sent: 08 September, 2003 16:29
To: www-rdf-interest@w3.org
Subject: OWL : Taxonomies VS. the semantic web a mismatch?

W3C has recognized the importance of taxonomies and is pushing "OWL Lite" as the new preferred way to express (web) taxonomies.  However, there appears to be a subtle but important semantic difference in how OWL is best used for taxonomies and how OWL is intended to be used for the semantic web. A difference that may destroy the semantic interoperability of OWL taxonomies and OWL for the semantic web.


When used for the semantic web the purpose is machine interpretability of Web content. Individual classes and instances describe the (metaphysical) things of existence, like the colour blue or the day of the week "Monday". OWL mark-up for a document (or other type of information objects) are formal semantic representations of what is described informally in the documents. 


When used to express classification hierarchies in taxonomies the purpose of OWL is to structure information objects in libraries, databases, portals etc. Individual classes describe topics/subjects such as Marketing,  R&D, Sales etc. Instances may (*) be the information objects under classification! OWL mark-up for a document (or other types of information objects) describe what the document is about (i.e. its classification).


(*) My recommendation to represent classification of "information objects" as class instances is arguably a misuse of the IS-A relation but it offers many benefits for taxonomy minded users/developers. 1) A simple information structure very similar to a taxonomy. 2) Out-of-the-box OWL reasoner support for relations between topics/subjects (e.x. reasoner will know that a book manually specified to be about a specific subject is also about the broader (parent) subjects in the taxonomy). 1+2) Lower costs, faster, easier, less training, less development.


In summary, key OWL constructs such as instances and subclassing will be used differently depending on the intended usage. I predict that the difference uses of OWL may inhibit the semantic interoperability of OWL taxonomies and OWL for the semantic web. (Will mostly be a problem of a future semantic web because the web may lose a valuable backbone of structured information).


I am interested in what other people have to say about this?

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Received on Tuesday, 9 September 2003 02:28:34 UTC

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