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

From: Brian McBride <bwm@hplb.hpl.hp.com>
Date: Tue, 24 Jul 2001 11:48:24 +0100
Message-ID: <3B5D5278.3CEA3E9A@hplb.hpl.hp.com>
To: pat hayes <phayes@ai.uwf.edu>
CC: w3c-rdfcore-wg@w3.org


pat hayes wrote:
> 
> >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).
> 
> Look at the assertions in your example, above. There are two
> existential claims made in there. One says that something (X) exists
> which bears the description-1 (ie the inverse of description)
> relation to advert123 and the product relation to roses and the
> minQuantity relation to some other thing Y.  X could be a 'service',
> sure. But what kind of thing is Y? It bears a units relation to kg
> and a minValue relation to 100. It sounds like a sale, or a
> transaction, or maybe a quantity of roses. But whatever it is, the
> sentences only assert that *one* of it exists. There is nothing here
> that could possibly convey what is meant by the English gloss of "a
> service that sells roses in quantities of at least 100 kg" (that is a
> hell of a lot of roses, by the way) , since that gloss uses the
> plural ("quantities"), but there isn't anything in the logical
> version that implies more than one of anything.

How about Y represents a range with a lower bound of 100Kg and an
unspecified upper bound. 

Regarding the quantity of roses, my colleague must love her dearly or
have done something very, very bad :)

[...]

> >What's a gensym error?
> 
> Assuming that a formal structure means more than it really does just
> because it seems to mean that when you read it as if it were English.
> Comes from a famous AI paper by Drew McDermott where he suggested
> that all 'intuitive' names be replaced by gensyms (LISP for genids)
> before you try to figure out what the axioms mean.

Ah - I recognise the paper from the description.

> 
> >
> > >
> > > > >
> > > > > 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.
> 
> The difference is that the Lassila example is purely existential, but
> this isn't.
> 
> >
> > > >
> > > >What is the difference between this and the example in:
> > > >
> > > >
> >http://lists.w3.org/Archives/Public/www-archive/2001Jun/att-0021/00-pa
> >rt#41
> > >
> > > That case asserts the existence of the un-identified individual.
> >
> >This case asserts the existence of an un-identified service.
> 
> Fine; but what it says about it is that it is connected with the
> existence of an un-identified quantity of roses. Not any such
> quantity: just one. 

Not so - see above.

Brian
Received on Tuesday, 24 July 2001 06:51:00 EDT

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