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Re: 2003-09-05 Semantics bug? "All classes are subclasses of themselves."

From: Graham Klyne <gk@ninebynine.org>
Date: Tue, 09 Sep 2003 13:23:41 +0100
Message-Id: <5.1.0.14.2.20030909132013.020651b8@127.0.0.1>
To: Dan Brickley <danbri@w3.org>, pat hayes <phayes@ihmc.us>
Cc: w3c-rdfcore-wg@w3.org

At 16:14 08/09/03 -0400, Dan Brickley wrote:

>* pat hayes <phayes@ihmc.us> [2003-09-08 10:15-0700]
> > >http://www.w3.org/TR/rdf-mt/#technote (informative) states,
> > >
> > >...ends with:
> > > "Notice that the question of whether or not a class contains itself as
> > > a member is quite different from the question of whether or not it is a
> > > subclass of itself. All classes are subclasses of themselves."
> > >
> > >Isn't this last observation a remnant of the old iff/extension version
> > >of rdfs:subClassOf ?
> >
> > Good catch, but we have imposed reflexivitiy of subClassOf, so its still
> > true.
>
>And there was me feeling all clever for a second ;)
>
>Can you explain briefly why subClassOf is reflexive now? (just curious,
>and to leave a papertrail... (apologies if it's in the spec someplace I
>missed)).

The reasons didn't get recorded in the minutes, but (since I just dug it 
out to check for myself) the meeting IRC log is here:

   http://www.w3.org/2003/06/27-rdfcore-irc

around 15:10.

Briefly, we could have gone either way on the reflexivity issue, it being 
pretty much orthogonal to intensionality, and it gives us a way to express 
a degree of equivalence between classes.   Also, it was less change to the 
existing spec.

#g


------------
Graham Klyne
GK@NineByNine.org
Received on Tuesday, 9 September 2003 08:39:28 EDT

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