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Re: User-defined Datatypes: owl:DataRange vs rdfs:Datatype

From: Dave Reynolds <der@hplb.hpl.hp.com>
Date: Thu, 07 Dec 2006 13:20:33 +0000
Message-ID: <45781521.2080702@hplb.hpl.hp.com>
To: Alan Ruttenberg <alanruttenberg@gmail.com>
CC: Holger Knublauch <holger@topquadrant.com>, public-owl-dev@w3.org

Alan Ruttenberg wrote:
> 
> The reference you give, among other things, says: "rdfs:Datatype is both 
> an instance of and a subclass of rdfs:Class. Each instance of 
> rdfs:Datatype is a subclass of rdfs:Literal."
> 
> So the build in datatypes such as xsd:int, by this definition, would be 
> a subclass of rdfs:Literal. However, according to [1] (OWL 1.0)
> 
> Definition: An OWL vocabulary V consists of a set of literals VL and 
> seven sets of URI references, VC, VD, VI, VDP, VIP, VAP, and VO. In any 
> vocabulary VC and VD are disjoint and VDP, VIP, VAP, and VOP are 
> pairwise disjoint. VC, the class names of a vocabulary, contains 
> owl:Thing and owl:Nothing. VD, the datatype names of a vocabulary, 
> contains the URI references for the built-in OWL datatypes and 
> rdfs:Literal.
> 
> If I understand this correctly,  it says that VC (the class names of a 
> vocabulary) and VD(the datatype names of a vocabulary) are disjoint. 
> That is, a datatype is not a class. Only classes have instances. So even 
> for the built-in xsd:int, the statement from RDFS "xsd:int, is a 
> subclass of rdfs:Literal" can't hold. And so user defined datatypes are 
> no different than the builtins.

Surely VC here is the set of owl:Classes which is a subset of the set of 
rdfs:Classes. The statement:

    xsd:int rdfs:subClassOf  rdfs:Literal .

can and does hold in RDFS, it is just that both of these are 
rdfs:Classes but not owl:Classes. Such a statement is of course not 
valid OWL/DL (and thus presumably not OWL 1.1) but it is perfectly good 
OWL (with species type OWL/full).

Dave

> 
> Does that look the appropriate answer to your question?
> 
> -Alan
> 
> [1] http://www.w3.org/TR/owl-semantics/direct.html#3.1
> 
> On Dec 6, 2006, at 7:48 PM, Holger Knublauch wrote:
> 
>>
>> Thanks, Jeff.  But in RDF Schema, the pre-defined system datatypes 
>> such as xsd:int are instances of rdfs:Datatype as well [1].  Are 
>> user-defined datatypes different from system datatypes, or is OWL 1.1 
>> changing the RDF Schema semantics here?  Apologies if this has been 
>> discussed and written down elsewhere - any pointers are appreciated.
>>
>> Regards,
>> Holger
>>
>> [1] http://www.w3.org/TR/rdf-schema/#ch_datatype
>>
>>
> 
> 
Received on Thursday, 7 December 2006 13:21:05 GMT

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