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

Re: Technical tweaks to the MT, for reviewers.

From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
Date: Sun, 10 Nov 2002 11:07:19 +0000
Message-Id: <5.1.0.14.2.20021110110626.03385440@127.0.0.1>
To: pat hayes <phayes@ai.uwf.edu>
Cc: w3c-rdfcore-wg@w3.org

At 01:28 PM 11/9/02 -0600, pat hayes wrote:
>>At 11:47 AM 11/8/02 -0600, pat hayes wrote:
>>>2. Now that subClassOf and subPropertyOf have 'iff' semantics, that 
>>>raises a slight complication: it means that anything with an empty class 
>>>extension, which right now includes anything that isn't a class, is a 
>>>subclass of anything, and similarly for properties. That has a lot of 
>>>unintuitive consequences, and I propose to remove them by *defining* 
>>>classes to be things that are in  rdfs:Class, similarly properties and 
>>>rdf:Property, and then restricting the 'iff' definition of subClassOf to 
>>>hold only between classes, and again similarly for properties.
>>
>>Can someone point me at the rationale for having iff rather than if here?
>
>Because without the IFF, subClassOf might not be transitive. Similarly 
>subPropertyOf. Peter P-S noticed this a while back. BUt more generally, it 
>seems best to nail down the sub-thingie meanings exactly since they are 
>kind of basic.

Gottit, thanks.  (When I asked that, I was getting confused between 
subclass and range, etc.)

#g


-------------------
Graham Klyne
<GK@NineByNine.org>
Received on Sunday, 10 November 2002 06:47:28 EST

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