W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > February 2002

type/dtype/subclassing and range/subproperties

From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
Date: Thu, 07 Feb 2002 17:42:57 +0000
Message-Id: <5.1.0.14.2.20020207172956.037e66b0@joy.songbird.com>
To: Pat Hayes <phayes@ai.uwf.edu>
Cc: Sergey Melnik <melnik@db.stanford.edu>, w3c-rdfcore-wg@w3.org
I finally figured out why 'dtype' is needed, but a corresponding extensions 
to 'range' is (maybe) not.

'type' inferences are intimately bound to subclassing, so the addition of 
subclassing assertions that are quite reasonable with respect to the value 
domains could completely mess up the datatyping.  (I'm sure you explained 
this Pat, but somehow I wasn't hearing.)

This did make me wonder is there might not be a similar problem with 
respect to 'range' and 'subPropertyOf':

    if    aaa range ddd    (ddd some datatype)
    and   bbb range ccc    (ccc some class)

then these statements don't say anything about literal interpretation for 
ccc, even if
     ccc subClassOf ddd
But adding:
     bbb subproperty aaa
also adds an inference
     bbb range ddd
which in turn invokes the dtype relation for subjects of bbb.

Just a thought.

#g
--

At 10:50 AM 2/7/02 -0600, Pat Hayes wrote:
>>Alternatively, why not just pretend there is a 'rule'
>>
>>   xxx rdf:type ddd .
>>   xxx rdf:value vvv .
>>   --->
>>   xxx ddd vvv .
>
>Well, use rdf:dtype rather than rdf:type, but yes; in fact this inference 
>is valid in the proposed MT extension in any case. But this doesnt do 
>range-datatyping by itself, as there is no RDFS inference path from 
>rdfs:range to rdf:dtype. I think its too dangerous to make people use 
>rdf:type, in general. It would be very tricky to be sure that some piece 
>of RDFS closure reasoning didn't accidentally make an unintended or 
>inconsistent datatype class association. The rdfs closure rules can have 
>very 'remote' consequences, involving things like subclasses of ranges of 
>subproperties.

------------------------------------------------------------
Graham Klyne                    MIMEsweeper Group
Strategic Research              <http://www.mimesweeper.com>
<Graham.Klyne@MIMEsweeper.com>
Received on Thursday, 7 February 2002 12:49:49 EST

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