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Re: [OEP] Draft of a note on n-ary relations

From: Alan Rector <rector@cs.man.ac.uk>
Date: Thu, 10 Jun 2004 16:58:30 +0100
Message-ID: <40C88526.481ADD94@cs.man.ac.uk>
To: Fabien Gandon <Fabien.Gandon@sophia.inria.fr>
Cc: public-swbp-wg@w3.org

Fabien

Today's telcon reminded me that I had not responded to this.

I think this approach has a serious problem in that it assumes that there an only be one temperature attached to one person.  If we were, for example, to extend the relation to include time, then we wouldn't know how to associate the various combinations.

In very abbreviated notation

Person    hasTemperature some (TemperatureQuality
                    atTime = 1994-05-05:12-28
                    hasLevel = elevated
                    hasTrend = decreasing

In this case, assuming that the relation hasTemperature is now not functional but the relations atTime, hasLevel and hasTrend are all functional, we can correctly ascribe a series of temperatures to a single person at different times.

The same thing occurs with any case in which the base relation - i.e. the relation that  is being re-represented as a property plus an incoming and several outgoing relations is not functional.

In addition, from experience, there are enough troubles keeping track of exploding Property hierarchies without overloading them in this manner :-)

In short,  I would be sceptical of this as a general solution although I admit it works in special cases.

Regards

Alan


Fabien Gandon wrote:

> Hello,
>
> I would like to extend my previous message [1] on n-ary relations, with
> another remark/option.
>
> Instead of using sub-properties to reify the roles of the n-ary property
> one could also use them to bear an additional qualification.
> For instance, to say that a person (John) has a temperature on 38 degree
> Celsius and increasing, one could also use the following representation:
>
> ex:hasATemperatureOf
>    rdf:type             rdf:Property
>
> ex:hasADecreasingTemperatureOf
>    rdfs:subPropertyOf   ex:hasATemperatureOf
>
> ex:hasAnIncreasingTemperatureOf
>    rdfs:subPropertyOf   ex:hasATemperatureOf
>
> ex:hasAStableTemperatureOf
>    rdfs:subPropertyOf   ex:hasATemperatureOf
>
> #John
>   ex:hasAnIncreasingTemperatureOf  "38D.C."
>
> Fabien
>
> [1] http://lists.w3.org/Archives/Public/public-swbp-wg/2004May/0128.html
> --
> "A speech belongs half to the speaker and half
>   to the listener." -- Michel E. de Montaigne.
>   ____________
> |__ _ |_  http://www-sop.inria.fr/acacia/personnel/Fabien.Gandon/
> |  (_||_) INRIA Sophia Antipolis - ph# (33)(0)4 92 38 77 88

--
Alan L Rector
Professor of Medical Informatics
Department of Computer Science
University of Manchester
Manchester M13 9PL, UK
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email: rector@cs.man.ac.uk
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Received on Thursday, 10 June 2004 11:58:37 UTC

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