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Re: Schema.org in RDF ...

From: David Booth <david@dbooth.org>
Date: Sat, 11 Jun 2011 17:57:32 -0400
To: Richard Cyganiak <richard@cyganiak.de>
Cc: Linked Data community <public-lod@w3.org>, Michael Hausenblas <michael.hausenblas@deri.org>
Message-ID: <1307829452.2165.36744.camel@dbooth-laptop>
On Sat, 2011-06-11 at 17:55 +0100, Richard Cyganiak wrote:
[ . . . ]
> > http://schema.org/Person is not the same as foaf:Person; one is a 
> > class of documents, the other the class of people.
> 
> I don't think that's correct at all. http://schema.org/Person is the 
> class of people and is equivalent to foaf:Person. It's just that the 
> schema.org designers don't seem to care much about the distinction
> between information resources and angels and pinheads. This is the
> prevalent attitude outside of this mailing list and we should come
> to terms with this.

Furthermore, the kind of ambiguity that this creates is *inescapable* in
general, and we simply need to learn to deal with it.  As long as an
application does not attempt to assert that foaf:Person is
owl:disjointWith the class of documents, there is no problem.  It is
only a problem for those applications the *need* to distinguish between
foaf:Persons and document.  Furthermore, there is a *cost* in making
finer distinctions than needed.  For example, an ontology that models
the world as flat costs less to process and maintain than one that
models the world as round, even though it is obviously "wrong" in some
sense.  But modeling the world as flat is *better* for an application
that is merely computing driving directions, because it is simpler, even
though it would be totally inadequate for an aircraft application.

Resource ambiguity is not something that should be viewed as an
absolute.  Rather, it is *relative* to a particular application: a URI
that is completely unambiguous to one application may be ambiguous to
another application that requires finer distinctions.

For more explanation of this, see myth #3 in "Resource Identity and
Semantic Extensions: Making Sense of Ambiguity":
http://dbooth.org/2010/ambiguity/paper.html#myth3

And see Pat Hayes's favorite example of the definition of Mount Everest:
http://lists.w3.org/Archives/Public/semantic-web/2011Mar/0242.html

While it is nicer to the community to avoid ambiguity that is *likely*
to cause problems to lots of applications, ultimately it is up to the
URI owner to decide what kinds of applications they want their URIs to
support.  OTOH, if your application will be negatively affected, there
is nothing wrong with lobbying the URI owner to change their ways to
better support *your* application.  At the same time, you should
recognize that *your* application is not *every* application.


-- 
David Booth, Ph.D.
http://dbooth.org/

Opinions expressed herein are those of the author and do not necessarily
reflect those of his employer.
Received on Saturday, 11 June 2011 21:58:10 UTC

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