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user defined datatypes

From: Jeremy Carroll <jjc@hpl.hp.com>
Date: Wed, 24 Sep 2003 13:10:04 +0300
To: www-webont-wg@w3.org
Message-Id: <200309241310.04181.jjc@hpl.hp.com>


At the last telecon we discussed user defined datatypes form a syntactic point 
of view, based on
http://lists.w3.org/Archives/Public/www-webont-wg/2003Sep/0154
and
http://lists.w3.org/Archives/Public/www-webont-wg/2003Sep/0181

Two new points:

1) my syntax checker now fails (only) five of the tests, including those that 
show the at risk feature and I5.8-016, the datatype test that is not in 
conformance with S&AS - i.e. the code I wrote a few months ago does what 
Peter thinks is the right thing. I am not intending to change this at the 
moment, since this was the datum that Dan was after.

2) I have been thinking about entailments ...

In OWL Full, if http://example.org/data/type is a supported datatype then

*empty*

entails

<http://example.org/data/type> rdf:type rdf:Datatype.

On the other hand if it is not a supported datatype then this is a 
non-entailment.

I worked from
http://www.w3.org/TR/rdf-mt/#dtype_interp
[[
if <aaa,x> is in D then I(aaa) is in ICEXT(I(rdfs:Datatype))
]]

In OWL DL, this is very unclear to me.

Also, if <http://example.org/data/type> is a supported datatype what is the 
status of the test file

<http://example.org/data/type> rdf:type owl:Thing .

for OWL Lite and OWL DL?

It feels like a syntax error to me.

I wonder whether the best approach is simply to be explicitly silent on this.
We have already said:
[[
Because there is no standard way to go from a URI reference to an XML Schema 
datatype in an XML Schema, there is no standard way to use user-defined XML 
Schema datatypes in OWL. 
]]
http://www.w3.org/TR/2003/CR-owl-semantics-20030818/syntax.html#2.1

what about extending that with
[[
Other aspects of user defined datatypes, are also deliberatedly
underspecied in this recommendation, but may be clarified in
later revisions.
]]
and then remove all tests with user defined datatypes.

Comments?

Jeremy
Received on Wednesday, 24 September 2003 07:10:11 GMT

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