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Re: Domain/Range: conjuntion or disjuntion??

From: Wolfram Conen <conen@gmx.de>
Date: Thu, 22 Nov 2001 16:20:37 +0100
Message-ID: <3BFD17C5.D7AE19CE@gmx.de>
To: Arjohn Kampman <akam@aidministrator.nl>
CC: www-rdf-interest@w3.org
Arjohn Kampman wrote:

I wrote:
>> ...
>> Does that sound reasonable to you, Arjohn?

Arjohn answered:
> I think so. I'll try to summarize for my own understanding:
> 
> - On a 'local' level (i.e. disregarding super properties) both conjunction
>   and disjuction interpretations are possible. So the range of a property p
>   can be restricted to e.g. D1 u D2.
> 
> - The range of a property is >*implicitely*< restricted to the 
>   conjunction of the range-restriction of the property itself and of 
>   its superproperties;e.g. p --range--> (D1 u D2) n C1 n C2
> 
> Is this what you were saying?
> 

Yes ;)  (yours is much more concise though...) - only "implicit" maybe a
bit misleading (I used it too), because it is just a consequence of
subProperty and range constraint working together. (let me also
emphasize again that the question of conjunctive/disjunctive
interpretation of multiple constraints have been related to the local
level)

> > Best,
> >       Wolfram
> >
> > PS: If we look at the "type inference" interpretation, the following
> > happens: if we add  s -p-> o, we have to add s -p1->o and s-p2->o again,
> > forcing/allowing us to infer that o is of the type C1 and of the type
> > C2. (the same information that we would have above about o if no range
> > constraints is violated, only this time, nothing could ever be violated
> > so no integrity could be checked).
> 
> Sure, but the type inference interpretation for RDFS, 
> as specified by the MT, was introduced long after we've 
> written the document. Integrity constraints
> were the way to go back then.
> 

That was my impression too. This PS was not meant as a critique on your
document (I like most of it, only the conclusion that where related to
the subproperty-stuff I do not share), I justed added it to emphazise
the differences of the interpretation (also giving a hint that the two
are not forward/backward compatible which should probably be noted in
the next version of RDFS clearly?).

Best regards,
	Wolfram
Received on Thursday, 22 November 2001 09:16:37 GMT

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