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Re: A use case for anon nodes - action from telecon

From: Brian McBride <bwm@hplb.hpl.hp.com>
Date: Fri, 20 Jul 2001 10:36:19 +0100
Message-ID: <3B57FB93.D9CAF7E1@hplb.hpl.hp.com>
To: Graham Klyne <Graham.Klyne@Baltimore.com>
CC: rdf core <w3c-rdfcore-wg@w3.org>


Graham Klyne wrote:
> 
> At 11:27 AM 7/19/01 +0100, Brian McBride wrote:
> >Loosely in English it means advert123 is for a service that will
> >buy roses in quantities of at least 100.
> >
> >                      advert123 role buyer
> >and  thereExists ?X  advert123 description ?X
> >                      ?X        product      roses
> >      thereExists ?Y  ?X        minQuantitiy ?Y
> >                      ?Y        units        kg
> >                      ?Y        minValue     100
> >
> >
> > >
> > > There seems to me to be no way of rendering this statement using just
> > > existential quantification.
> >
> >As  you see, I've made an attempt.
> 
> Good, thanks!
> 
> The problem I now see is that this asserts the existence of the required
> service:
> 
>    thereExists ?X which is the object of (advert123 description ?X)
>    (etc)

I think the intent here was to assert the existence of the buyer service,
which does exist (for some definition of exist).

The game that is being played here is that this example is not being
presented as a query.  Rather than say please find me X, one is saying
exists Y such that Y is a consumer of X.

> 
> But the apparent intent of this is ask if such a service exists.  Do I
> detect a "gensym" error?

What's a gensym error?

> 
> > >
> > > This may be a compelling use-case, but I don't see any sanction for this
> > > usage in M&S 1.0, and as such would suggest it be deferred to V2.0.

Then you must show how it is different from the Lassila example in M&S.


> >
> >What is the difference between this and the example in:
> >
> >   http://lists.w3.org/Archives/Public/www-archive/2001Jun/att-0021/00-part#41
> 
> That case asserts the existence of the un-identified individual.

This case asserts the existence of an un-identified service.

Brian
Received on Friday, 20 July 2001 05:39:18 EDT

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