W3C home > Mailing lists > Public > semantic-web@w3.org > March 2011

Re: {Disarmed} Re: blank nodes (once again)

From: Dieter Fensel <dieter.fensel@sti2.at>
Date: Thu, 24 Mar 2011 23:10:02 +0100
To: Enrico Franconi <franconi@inf.unibz.it>, "<semantic-web@w3.org> Web" <semantic-web@w3.org>
Cc: Pat Hayes <phayes@ihmc.us>,Hugh Glaser <hg@ecs.soton.ac.uk>, Mark Wallace <mwallace@modusoperandi.com>, Alan Ruttenberg <alanruttenberg@gmail.com>, Reto Bachmann-Gmuer <reto.bachmann@trialox.org>, Ivan Shmakov <oneingray@gmail.com>,Ivan Shmakov <ivan@main.uusia.org>
Message-ID: <E1Q2sjg-0008LW-8s@lisa.w3.org>
At 22:30 24.03.2011, Enrico Franconi wrote:
>I believe that there is a major misunderstanding by the 
>non-logicians about bnodes, existential variables, and skolem constants.

Thanks for classifying me properly.

>At the end of this message I compiled a sequence of statements from 
>this thread which show this misunderstanding.
>
>As we all know it is correct that a bnode in RDF can be equivalently 
>represented as a skolem constant (or as an existential variable, but 
>here I'm not concerned about that).
>The whole point is that a bnode once skolemised does NOT behave like 
>any other constant, since it should be UNIQUE all around the world

Well, URIs or the work of OCCAM in Trento work precisely on this type of stuff.
For example, getting unique or universal identifiers in the Internet 
of Things area (*) is
an active area of research at the moment. Much more interesting than discussing
again and again about the hair cut of Aristotle. And even if some 
solutions will brake occasionally this is
as relevant as a broken link on the web. How many "wrong" same-as statements
are on LOD because OWL cannot incorporate the perspective of an observer
in its primitive notion of equality? Instead of receiving free 
lectures on logics by
University professors I would prefer to free people to focus on 
rocket engineering.

(*) what about a random number?

>and at any time; indeed, it is a skolem constant. To avoid this 
>impossible requirement in practice, 'scoping' within a graph

Which graph? The RDF working group is trying hard to establish such a notion!

>is introduced, with all the consequences it bears. The scoping 
>annoyances have nothing to do with logicians pretending them :-)
>So, the idea of dropping bnodes by transforming them to plain 
>constants would be incompatible with the original bnode semantics, 
>since you can not guarantee the unicity wherever whenever. Under 
>this simplifying idea, bnodes would be just as any other constant 
>and therefore there would be no reason to even consider them.
>
>For this reason, I agree (again!) with Pat:

Me too.
-- 
Dieter Fensel
Director STI Innsbruck, University of Innsbruck, Austria
http://www.sti-innsbruck.at/
phone: +43-512-507-6488/5, fax: +43-512-507-9872
Received on Thursday, 24 March 2011 22:10:34 UTC

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