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Re: RDF semantics, access control description and timeranges

From: Dan Connolly <connolly@w3.org>
Date: 16 Dec 2002 09:40:07 -0600
To: Graham Klyne <GK@NineByNine.org>
Cc: www-rdf-calendar <www-rdf-calendar@w3.org>
Message-Id: <1040053206.11337.2.camel@dirk.dm93.org>

I hope to reply in substance presently, but
I'm not sure I'll be able to...

On Sun, 2002-12-15 at 07:33, Graham Klyne wrote:
[...]
> It seems that, using RDF, it is difficult to construct usage scenarios in 
> which adding additional properties can be used to refine the precision of 
> what is specified.  To do that requires a form of default reasoning, which 
> is non-monotonic.
> 

Indeed, this is a recurring issue; I'm working on proving
that my new calendar knows everything my old calendar knew,
and I'm wrestling with this issue; in particular, I have
rules ala

	IF it's an event with a date-time and timezone, do x
	ELSE do Y

well, I can't tell that it's *not* an event with  a date-time
based on lack of information.

I'm using log:notIncludes to do it.

More later, I hope.


> I'm left thinking that some practical guidelines are required to avoid such 
> potential problems in general RDF use.
> 
-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Monday, 16 December 2002 10:40:22 UTC

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