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[LC Response #2] to Jan Wielemaker, Re: Triples and OWL2

From: Ivan Herman <ivan@w3.org>
Date: Wed, 18 Mar 2009 19:28:27 +0100
Message-ID: <49C13D4B.7070108@w3.org>
To: J.Wielemaker@uva.nl
CC: public-owl-comments@w3.org
Dear Jan,

This is an answer to your message

giving further comments on the OWL 2 Web Ontology Language last call drafts.

You are correct that a completely XML "friendly" encoding of RDF could
indeed be used to encode OWL 2 ontologies and could, therefore, be used
as part of a more complete XML workflow. There are, however, several
issues that must be considered.

First of all, as you yourself noted, developing such an XML encoding is
not in the charter of the OWL 2 Working Group. Taking into account the
fact that there is no group at the moment whose charter could reasonably
include such a development, that means that, in the meantime, the needs
of a distinct community would not be fulfilled for a long time.

There is, however, a further issue to consider. Let us suppose that a
regular XML encoding, closely reflecting RDF triples, was used
(something like TriX[1], for example). That would mean that OWL
construct would have to be encoded in, essentially, an XML
transliteration of N-triples. Though this would be well defined, it
would still be complicated to manage the resulting XML content through,
say, XPath, and almost impossible to define an XML schema that could be
used by a schema aware editor. This is simply due to the fact that the
triple representation of OWL constructs are, by their very nature,
fairly complex (think of the representation of class intersections using
RDF lists). One could of course imagine a slightly more complex XML
encoding of RDF, but it is unclear at the moment what that would be. In
other words, relying on a generic XML format for RDF may not satisfiy
the requirements end users have for such a serialization of OWL due to
its inherent complexity.

Note that having specialized formats for 'sub'-languages on the Semantic
Web is not specific to OWL. A typical example might be the XML encoding
of Resource Descriptions in POWDER[2], which provides an XML syntax for
end users but also defines a formal transformation of that XML encoding
into OWL. As long as these languages clearly map on a common and
required exchange format (which is the case for OWL 2), they can be
valuable in serving various specialized communities without damaging

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Ivan Herman
on behalf of the W3C OWL Working Group

[1] http://www.hpl.hp.com/techreports/2004/HPL-2004-56.html
[2] http://www.w3.org/TR/powder-primer/

Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
mobile: +31-641044153
PGP Key: http://www.ivan-herman.net/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf

Received on Thursday, 19 March 2009 08:48:13 UTC

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