W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > July 2001

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

From: Graham Klyne <Graham.Klyne@Baltimore.com>
Date: Mon, 23 Jul 2001 22:06:32 +0100
Message-Id: <5.1.0.14.2.20010723215409.03bc6840@joy.songbird.com>
To: Brian McBride <bwm@hplb.hpl.hp.com>
Cc: rdf core <w3c-rdfcore-wg@w3.org>
Brian,

OK, I think I get it now.  You're right about me committing the gensym 
error.   (FWIW, it was "product roses" that got me.   "productType roses" 
might have guided me around this pitfall.)

I now accept that neither buyer nor seller service logically assert the 
existence of the product potentially transacted.

So where does this leave the original discussion?  I think we still have 
every anonymous resource being something whose existence is asserted.

#g
--

At 07:57 AM 7/23/01 +0100, Brian McBride wrote:


>Graham Klyne wrote:
>[...]
> > I'm fine with asserting the existence of the buyer service.  The problem I
> > have is that the *description* of the buyer service asserts the existence
> > of something that may not actually exist.
>
>I'm obviously not being clear.  In
>
> > >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
> > >
>
>?X denotes a service that will BUY roses in minimum quantities of 100kg.
>
>There does exist a service that can be bound to ?X.  Its the buyer
>service.  That's what we're advertising here.
>
>Or was it ?Y you were suggesting could not be satisfied.
>
>
> >
> > > > But the apparent intent of this is ask if such a service exists.  Do I
> > > > detect a "gensym" error?
> > >
> > >What's a gensym error?
> >
> > An expression Pat used recently, if I get it right, to describe logical
> > errors introduced by human interpretation of a symbol in an expression
> > without any logical basis for that interpretation.
>
>Then I'm hoping you have now :)
>
>
> >
> > In this case, we know what a "buyer" is, and what a "seller" is.
> >
> > The two examples you gave in
> > http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Jul/0240.html are
> > identical modulo a name change and a quantity.  (Pedagogically, they could
> > equally have been stated using the same quantity so that the only
> > difference was a name change.)
> >
> > Yet we infer that in one case the goods offered for sale definitely exist,
> > but in the other case no assertion is made about their existence.  There
> > seems to be no *logical* basis for this difference in interpretation when
> > the only difference is a naming difference.
> >
> > Currently, it seems to me that the Existential-Conjunctive (EC) subset of
> > first order logic, hence RDF as I understand it, is incapable of expressing
> > the buyer proposition without actually asserting the existence of that
> > which is to be purchased.
>
>Of course it can.  If it can assert that a seller service exists, surely
>it can equally well assert that a buyer service exists.  It doesn't know
>the difference.
>
>Brian
>
>
>This footnote confirms that this email message has been swept by
>MIMEsweeper for the presence of computer viruses.

------------------------------------------------------------
Graham Klyne                    Baltimore Technologies
Strategic Research              Content Security Group
<Graham.Klyne@Baltimore.com>    <http://www.mimesweeper.com>
                                 <http://www.baltimore.com>
------------------------------------------------------------
Received on Monday, 23 July 2001 18:05:37 EDT

This archive was generated by hypermail pre-2.1.9 : Wednesday, 3 September 2003 09:38:14 EDT