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RE: A proposal for clarifying the definitions of datatype maps

From: Boris Motik <boris.motik@comlab.ox.ac.uk>
Date: Thu, 14 May 2009 16:50:42 +0200
To: "'Michael Schneider'" <schneid@fzi.de>
Cc: "'W3C OWL Working Group'" <public-owl-wg@w3.org>
Message-ID: <6834D41284F84A788B3BEADB3A794E9F@wolf>
Hello Michael,

Please find my answers inline.



> -----Original Message-----
> From: public-owl-wg-request@w3.org 
> [mailto:public-owl-wg-request@w3.org] On Behalf Of Michael Schneider
> Sent: 06 May 2009 12:34
> To: Boris Motik
> Cc: W3C OWL Working Group
> Subject: RE: A proposal for clarifying the definitions of datatype 
> maps
> Hi Boris!
> Boris Motik wrote on Thursday, April 30, 2009:
> >Hello,
> >
> >Michael pointed out in one of his review of conformance that the 
> >definitions of datatypes might benefit from further clarification. In 
> >fact, I have noticed that there is a slight inconsistency between the 
> >Syntax and the Conformance documents regarding datatypes in OWL 2 DL. 
> >Conformance explicitly says that an OWL
> >2 DL
> >ontology must not contain datatypes other than the datatypes 
> >mentioned in the OWL 2 datatype map; however, this is not reflected 
> >in the Syntax document, where Section 5.2 implies that an OWL 2 DL 
> >ontology could include datatypes that are not in the OWL 2 datatype 
> >map. As Conformance is more restrictive its conditions on datatypes 
> >are the ones that actually hold.
> [...]
> >In Direct Semantics:
> >
> >Clarify that the datatype map D (used throughout the document) must 
> >coincide with the OWL 2 datatype map on the definition of the 
> >semantics of the datatypes from Section 4.
> I'm not sure what the word "coincide" refers to here. There are two 
> aspects I can see:
> Aspect (1): Do you meant that if, for example, the datatype name "xsd:float"
> is used in a datatype map as defined in the Direct Semantics, then the 
> semantics of this datatype must *coincide* with the definition of 
> xsd:float given in the Structural Spec. This would indeed be an 
> obvious requirement to me, and I would agree that it should be said 
> explicitly in the Direct Semantics. So no issue with this on my side.

This is precisely what I mean.

> But I wonder whether you ask for more than just (1). I can see that 
> the definitions of datatype maps, vocabularies and interpretations in 
> the Direct Semantics are stated in a very general way, and do not make 
> any reference to the concrete set of datatypes listed in the 
> Structural Spec. So do you want to change this in the way that

I don't want to say which datatypes need to be included into the datatype map.
This is mainly because of the theorem DS1: it should be applicable to any
datatype map regardless of whether it contains all, some, or none of the
datatypes mentioned in Section 4 of Syntax.

Therefore, I think we should simply say that, if D includes one of the
datatypes, then it should define the datatype in the same way as in Section 4.

> Aspect (2): the set of datatype names in a datatype map must 
> *coincide* with the set of datatype names listed in the Structural 
> Spec, i.e. a datatype map used in the Direct Semantics must contain 
> those and only those datatypes that are given in the Structural Spec?

No, I didn't mean to say that. This is just a bug in the way I expressed the
condition in the e-mail; however, the text I'd like to add to Syntax would not
reflect this interpretation.



> I would consider (2) a strong restriction compared to the current 
> situation, because it wouldn't allow implementers to provide new 
> datatypes (theorem in Section 3 would become redundant then, AFAICT).
> Michael
> --
> Dipl.-Inform. Michael Schneider
> Research Scientist, Dept. Information Process Engineering (IPE) Tel  : 
> +49-721-9654-726 Fax  : +49-721-9654-727
> Email: michael.schneider@fzi.de
> WWW  : http://www.fzi.de/michael.schneider
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Received on Thursday, 14 May 2009 14:52:08 UTC

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