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Re: Managing Co-reference (Was: A Semantic Elephant?)

From: Richard Cyganiak <richard@cyganiak.de>
Date: Thu, 15 May 2008 11:20:40 +0100
Cc: "Michael F Uschold" <uschold@gmail.com>, Tim Berners-Lee <timbl@w3.org>, Sören Auer <auer@informatik.uni-leipzig.de>, Semantic Web Interest Group <semantic-web@w3.org>, Chris Bizer <chris@bizer.de>, Frank van Harmelen <Frank.van.Harmelen@cs.vu.nl>, Kingsley Idehen <kidehen@openlinksw.com>, "Fabian M. Suchanek" <f.m.suchanek@gmail.com>, Tim Berners-Lee <timbl@csail.mit.edu>, Jim Hendler <hendler@cs.rpi.edu>, Mark Greaves <markg@vulcan.com>, georgi.kobilarov@gmx.de, Jens Lehmann <lehmann@informatik.uni-leipzig.de>, Frederick Giasson <fred@fgiasson.com>, Michael Bergman <mike@mkbergman.com>, Conor Shankey <cshankey@reinvent.com>, Kira Oujonkova <koujonkova@reinvent.com>
Message-Id: <55B89ED2-8D27-4DFE-92EC-2404639E6E54@cyganiak.de>
To: Aldo Gangemi <aldo.gangemi@cnr.it>


Please keep your facts straight.

On 14 May 2008, at 22:24, Aldo Gangemi wrote:
> owl:sameAs is great to co-reference persons, places, etc. It is  
> buggy when used to relate e.g. foaf:Person
> instances to persons' homepages,

I would like to point out that I haven't come across any instance  
where this has been done or encouraged.

> or a city as from Cyc to a wikipedia article of that city (as done  
> in DBpedia).

DBpedia doesn't contain any owl:sameAs statements between Cyc  
resources and Wikipedia articles.

> It is reasonable, as Richard Cyganiak wrote at the time, that we  
> have to work around the quirks [2], nonetheless, if there is no real  
> need, why should we work around the quirks caused by a pointless  
> identity assumption?

I feel misquoted. In the original discussion [1], I encouraged the use  
of owl:sameAs between three different definitions (Geonames, GEMET and  
DBpedia) of the concept of a “canal”. I did *not* advocate to gloss  
over the difference between a thing and a document about that thing,  
as you imply by your examples above. To the contrary, I have insisted  
on this difference many times, e.g. in [2].

At the end of the day, we have to keep in mind that we are talking  
about the Web. Statements will be subjective, inconsistent and wrong.  
This also applies to owl:sameAs statements. They are claims, not  
facts. Deal with it.


[1] http://simile.mit.edu/mail/ReadMsg?listName=Linking%20Open%20Data&msgId=14215
[2] http://www.w3.org/TR/cooluris/

> Notice that ignoring owl:sameAs is not a good solution. We need some  
> trade-off between simplicity
> and formality. A basic similarity relation is perfect, and then  
> those triples can be worked out automatically,
> by means of appropriate metamodels, e.g. as proposed in [3].
> Aldo
> [1] Bernard Vatant suggested some good practice of mutual linking:
> http://universimmedia.blogspot.com/2007/07/using-owlsameas-in-linked-data.html
> [2] Cyganiak quote:
>> People who want to re-use your data will learn to work around its  
>> quirks and idiosyncrasies.
>> Dealing with the quirks is a part of re-using data, it always was,  
>> and it always will be.
> [3] http://www.ibiblio.org/hhalpin/irw2006/vpresutti.pdf from IRW  
> workshop: http://www.ibiblio.org/hhalpin/irw2006/
> _________________________________
> Aldo Gangemi
> Senior Researcher
> Laboratory for Applied Ontology
> Institute for Cognitive Sciences and Technology
> National Research Council (ISTC-CNR)
> Via Nomentana 56, 00161, Roma, Italy
> Tel: +390644161535
> Fax: +390644161513
> aldo.gangemi@cnr.it
> http://www.loa-cnr.it/gangemi.html
> icq# 108370336
> skype aldogangemi
Received on Thursday, 15 May 2008 10:22:40 UTC

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