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Re: [Dbpedia-discussion] Using DBpedia resources as skos:Concepts?

From: Richard Cyganiak <richard@cyganiak.de>
Date: Fri, 13 Nov 2009 16:35:47 +0000
Cc: "Sandhaus, Evan" <sandhes@nytimes.com>, Pat Hayes <phayes@ihmc.us>, SKOS <public-esw-thes@w3.org>
Message-Id: <A582C84B-95D1-44A7-9F54-F4C394CEB9CD@cyganiak.de>
To: Bernard Vatant <bernard.vatant@mondeca.com>

On 13 Nov 2009, at 14:24, Bernard Vatant wrote:
> If you confuse your concept A for the thing X and X itself, maybe  
> you can
> live inside your system with this. No real conflict, just  
> superposition of
> different "views" of the same referent, a direct and an indirect  
> one. A bit
> weird, but no real formal inconsistency so far, if the respective  
> ontologies
> you use don't forbid it by assertions such as skos:Concept  
> owl:disjointWith
> foaf:Person.

Right. If I do this locally, there should be no harm.

> But if I confuse also my concept B with the same thing X, and
> a third party puts all that together out of context, it will merge A  
> and B,
> and from there clear inconsistencies will appear, like two different  
> valuse
> of creation date, or two different values of dcterms:publisher.

This argument holds against the use of owl:sameAs, but not against the  
use of skos:closeMatch, which will not result in a "merge" of A and B;  
it will only result in the conclusion that the "middle" resource X is  
both a skos:Concept and a, say, foaf:Person.

> If the
> supporting ontology says that dcterms:publisher has max cardinality  
> 1, the
> two publishers will be inferred to be the same, merging some of their
> attributes, and so on. That's what I meant, Richard, by "trigger a  
> semantic
> collapse".

Again, does not apply to skos:closeMatch. Where is the "semantic  
collapse" you predicted in that case?

> If all URIs are ambiguous as Pat holds it, and I tend to agree, and  
> default
> general mechanisms able to resolve this ambiguity so far, we're  
> better be
> cautious, given the current dumbness of our systems and keep the  
> ambiguity
> as limited as possible. Which means, when you see clearly undesirable
> consequences of overloading, don't do it.

I fully agree with the sentence: When you see undesirable consequences  
of overloading, don't do it. But I do not see those consequences for  
the use of skos:closeMatch. Where are they?


> I think the example we have been
> discussing for a week clearly belongs to this category. There are more
> subtle cases of ambiguity, already discussed at large in the past  
> without
> clear solution, like what do we do with Berlin having a single URI in
> DBpedia and two different ones at least in Geonames with distinct  
> referents
> (the populated place and the administrative division).
> Bernard
> 2009/11/13 Sandhaus, Evan <sandhes@nytimes.com>
>> Just a quick thought to throw fuel on the fire with respect to SKOS  
>> and
>> owl:sameAs.
>> The question is asked.  Can we declare a resource R of type  
>> skos:concept to
>> be owl:sameAs a resource S which is of some "real-world" type (say  
>> person,
>> place, etc)?  To make this assertion, it is argued, would be to  
>> assert that
>> S is a skos:concept, which to many (though not me) seems nonsense.
>> It is suggested by some that perhaps we instead say that R is
>> skos:[exactMatch|closeMatch|narrow|broader] to S.  However, it  
>> turns out
>> that the range of these properties is skos:concept, so you are again
>> asserting that S is of type skos:concept.
>> So you don't really resolve this dilemma using skos predicates, you  
>> just
>> make it slightly more obscure.
>> I am of the mind however, that skos:concept(s) need not be mutually
>> exclusive from their real world counterparts.  After all, when one  
>> examines
>> the indexing vocabulary of (say) a book and finds the subject heading
>> "United States of America" that heading is at once both a "subject
>> heading/concept" and - it seems to me - inarguably also a country.   
>> The
>> fundamental question seems to be can a subject heading at once  
>> signify and
>> be an object.  And, at least to my mind, I think it can.
>> Does this square with the exact language of the SKOS recommendation?
>> Probably not, but - since the original intent of skos - was to  
>> provide a
>> framework for expressing indexing vocabularies (knowledge  
>> organization
>> systems), it seems (to me) very much in keeping with the spirit of  
>> the
>> effort.
>> Anyways, that's my $0.02.
>> All the best,
>> Evan Sandhaus
>> --
>> Evan Sandhaus
>> Semantic Technologist
>> New York Times Research + Development
>> @kansandhaus
>> (212)556-3826
> -- 
> Bernard Vatant
> Senior Consultant
> Vocabulary & Data Engineering
> Tel:       +33 (0) 971 488 459
> Mail:     bernard.vatant@mondeca.com
> ----------------------------------------------------
> Mondeca
> 3, cité Nollez 75018 Paris France
> Web:    http://www.mondeca.com
> Blog:    http://mondeca.wordpress.com
> ----------------------------------------------------
Received on Friday, 13 November 2009 16:36:22 UTC

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