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Re: A description of the changes necessary to implement named data ranges

From: Ivan Herman <ivan@w3.org>
Date: Fri, 06 Mar 2009 11:40:21 +0100
Message-ID: <49B0FD95.1000807@w3.org>
To: Boris Motik <boris.motik@comlab.ox.ac.uk>
CC: 'W3C OWL Working Group' <public-owl-wg@w3.org>
Just to clarify: what about OWL RL? Can I name a specific
DataIntersection (which is allowed there)? If so, there might be effects
on the Profile document, too.

Ivan

Boris Motik wrote:
> Hello,
> 
> Here is a description of how the named data range extension would work. In
> short, we'd introduce a new type of axioms called DatatypeDefinition. These
> would allow you to define a datatype as having some built-in value. Then, you
> would be able to write something like this:
> 
> (1) Declaration( Datatype( a:myDT ) )
> (2) DatatypeDefinition( a:myDT DatatypeRestriction( xsd:integer ... ) )
> 
> Note that (1) is necessary because without it, axiom (2) alone would invalidate
> the typing constraints (it would use a URI that is not properly typed). These
> axioms would be mapped into RDF into (3) and (4), respectively:
> 
> (3) a:myDT rdf:type rdfs:Datatype
> (4) a:myDT a:equivalentClass ...
> 
> 
> We would call datatypes occurring in such axioms '''defined'''. To obtain a
> logic with favorable computational properties, in OWL 2 DL we'd have the
> following conditions:
> 
> - If the axiom closure contains a datatype declaration, then the datatype MUST
> be in the datatype map or the axiom closure MUST contain a datatype definition
> for the datatype.
> 
> - A datatype definition axiom MUST NOT define a datatype that is in the datatype
> map.
> 
> - Datatype definitions MUST be acyclic.
> 
> - Datatype restrictions MUST involve only datatypes from the datatype map - that
> is, the datatypes defined through datatype definition axioms have no facets.
> 
> 
> 
> All these changes would be reflected in the Syntax document. The impact to all
> other documents would be quite small:
> 
> - Changes to RDF Mapping are minimal and involve mapping the new axiom (into RDF
> and back); both changes are minimal.
> 
> - Changes to Direct Semantics are minimal and involve defining the semantics of
> the new axiom.
> 
> - Changes to the XML Syntax are minimal and involve adding a new axiom.
> 
> - There are no changes to the RDF-Based Semantics.
> 
> Regards,
> 
> 	Boris
> 
> 

-- 

Ivan Herman, W3C Semantic Web Activity Lead
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Received on Friday, 6 March 2009 10:40:52 GMT

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