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Re: XMLLiteral in OWL

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Thu, 22 Jan 2004 17:24:20 +0000
Message-ID: <16400.1860.835151.210274@galahad.cs.man.ac.uk>
To: herman.ter.horst@philips.com
Cc: www-webont-wg@w3.org, "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>

I believe that we should keep changes to an absolute minimum.

I don't believe that the change proposed by Herman, or either of the
first two changes proposed by Jeremy are necessary because they only
aim to make explicit what is already implicit).

I believe that we should make the third change proposed by Jeremy,
i.e., to modify test miscellaneous-205 by deletion of the word "Full"
from its levels box - this slightly weakens the test and alleviates
the problem that it may really be incorrect in its current form.

Ian



On January 19, herman.ter.horst@philips.com writes:
> 
> During the last telecon I was actioned with Jeremy and Ian
> to look at the problem of XMLLiteral in OWL and propose
> a decision [1].
> In this message I summarize the problem and the decision
> that was already proposed during the meeting.
> (See, e.g., [3-7]  for earlier discussion about this problem.)
> 
> Problem
> - The OWL design allows the possibility of doing without 
> semantic conditions on XMLLiteral.  This is visible in
> the Test document (see tests 201-205).
> - S&AS Section 5 (RDF-compatible model-theoretic semantics)
> does not allow the possibility of doing without semantic
> conditions on XMLLiteral.  OWL Full interpretations as well
> as OWL DL interpretations are D-interpretations (from the
> RDF Semantics document) and thereby always incorporate
> semantic conditions on XMLLiteral.
> - This mismatch between S&AS and Test disturbs a bigger
> point: as is described in the first paragraph of Test,
> S&AS is the primary normative document about OWL, and
> Test is a 'subsidiary' document, aiming to give examples
> and clarification of S&AS.     As I wrote earlier,
> >If the document
> >is left with an error like this, how can a reader decide
> >for any statement of S&AS whether it is reliable?
> 
> Example: the RDF graph
>       v p l
>       p rdfs:range rdfs:Literal
> where l is an ill-typed XML literal, is DL and 
> Full-inconsistent according to S&AS Section 5,
> whether the datatype map D contains XMLLiteral or not.
> Test allows the possibility to not include XMLLiteral
> in the datatype map, in which case this RDF graph
> becomes consistent for DL or Full.
> 
> ==
> 
> Proposed solution:
> 
> incorporate the three changes precisely described in 
> Jeremy's note "possible compromise on rdf:XMLLiteral" [2]
> *and* add one sentence to S&AS Section 5 following
> the sentence just before Section 5.1:
>   "If, however, any conflict should ever arise between
>   these two forms, then the Direct Model-Theoretic
>   Semantics takes precedence."
> The new sentence following this sentence should express
> that this applies (so that the direct semantics takes
> precedence) when XMLLiteral is not in the datatype map.
> 
> (To summarize, the three changes described by Jeremy in [2]
> ensure that
> -an OWL interpretation (S&AS Section 5.2) always assumes
> XMLLiteral in its datatype map (not mentioning this
> would misleadingly suggest that this is not necessary)
> -the datatype map for OWL Full always includes XMLLiteral
> -Test 205 does not apply to OWL Full.)
> 
> During the last telecon support for this solution was expressed
> by Jeremy and me.
> 
> 
> Herman
> 
> [1] http://lists.w3.org/Archives/Public/www-webont-wg/2004Jan/0040.html
> [2] http://lists.w3.org/Archives/Public/www-webont-wg/2003Dec/0100.html
> 
> [3] http://lists.w3.org/Archives/Public/www-webont-wg/2003Dec/0035.html
> [4] http://lists.w3.org/Archives/Public/www-webont-wg/2003Dec/0042.html
> [5] http://lists.w3.org/Archives/Public/www-rdf-comments/2003OctDec/0233.html
> [6] http://lists.w3.org/Archives/Public/www-webont-wg/2003Dec/0102.html
> [7] http://lists.w3.org/Archives/Public/www-webont-wg/2003Dec/0106.html
Received on Thursday, 22 January 2004 12:27:31 GMT

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