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Re: Chainsaw?

From: Tom Van Eetvelde <tom.van_eetvelde@alcatel.be>
Date: Wed, 08 Nov 2000 11:08:34 +0100
Message-ID: <3A092622.9DC82CC1@alcatel.be>
To: Graham Klyne <GK@Dial.pipex.com>
CC: RDF interest group <www-rdf-interest@w3.org>
Hello Graham,

Good point there. I had some problems trying to catch what you want to say via the Ford Example (if
Ford_escort is defined by FordMotorCOmpany, then this automatically applies to all class instances
as well in my reasoning world). But I found an example that makes things perfectly clear:

Suppose you have the class insects. You want to say that this class is big. That doesn't mean of
course that every class instance is big.

Can this be solved via a new constraintproperty 'commonInstanceValue' (I am not creative enough at
the moment to invent a nice name) and leaving 'domain' as it is in the specification? This way, it
is explicit which class properties may be applied to class instances and instances of subclasses and
which not.



Graham Klyne wrote:

> At 11:26 AM 10/23/00 +0200, Tom Van Eetvelde wrote:
> >Bad idea! :-) I believe my proposal can model in a more natural way what
> >you want to do.
> Tom,
> I accept that my original idea was not great, but I have one problem with
> your proposal.  My concern applies to your proposal in the "definition of
> domain" thread, and also to the counter-example you offer to mine:
> ><rdfs:Class ID="Ford_Escort">
> ><rdfs:subClassOf rdf:resource="Car"/>
> ><s:bodyStyle> Hatchback </s:bodyStyle>
> ><s:engine_fueltype> Petrol </s:engine_fueltype>
> ></rdfs:Class>
> I accept the idea of using a class as a kind of prototype, but have a
> problem with this particular representation.  Specifically, how statements
> about the class be distinguished from statements about instances of the
> class;  e.g.  I might wish to say something like:
>     [FordEscord] --rdf:type---> [rdfs:Class]
>     [          ] --definedBy--> [FordMotorCompany]
>     [          ] --bodyStyle--> "HatchBack"
>     (etc.)
> Here, the intent of the properties "definedBy" and "bodyStyle" is very
> different.  One is a statement about the class itself, and the other is a
> prototype for instances of the class.
> I'm still thinking about this stuff, so I'll pursue this further as I bet
> my ideas sorted.
> #g
> --
> ------------
> Graham Klyne

Received on Wednesday, 8 November 2000 05:10:33 UTC

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