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Re: Issue-57

From: David Booth <david@dbooth.org>
Date: Mon, 13 Jun 2011 16:50:48 -0400
To: Jonathan Rees <jar@creativecommons.org>
Cc: Jeni Tennison <jeni@jenitennison.com>, "www-tag@w3.org List" <www-tag@w3.org>
Message-ID: <1307998248.2165.39789.camel@dbooth-laptop>
On Mon, 2011-06-13 at 13:51 -0400, Jonathan Rees wrote:
> On Mon, Jun 13, 2011 at 11:30 AM, Jeni Tennison <jeni@jenitennison.com> wrote:
> > Hi,
> >
> > For those who don't follow it, there's a thread on httpRange-14 / Issue-57 at the moment on the linked data mailing list. A good example message is:
> >
> >  http://lists.w3.org/Archives/Public/public-lod/2011Jun/0186.html
> >
> > where Richard says:
> >
> >  Being useful trumps making semantic sense. The web succeeded *because*
> >  it conflates name and address. The web of data will succeed *because*
> >  it conflates a thing and a web page about the thing.
> >
> >  <http://richard.cyganiak.de/>
> >    a foaf:Document;
> >    dc:title "Richard Cyganiak's homepage";
> >    a foaf:Person;
> >    foaf:name "Richard Cyganiak";
> >    owl:sameAs <http://twitter.com/cygri>;
> >    .
> >
> > I don't think that this is covered by any of the scenarios in Jonathan's document at:
> My *intent* was that this situation would be covered by
>   4.4 Coerce an information resource to what it defines its URI to name
> but I guess the section name and description are not adequately evocative.
> I actually don't object to this attitude too much; if people want to
> opt out of machine inference who am I to say otherwise. They
> themselves say they don't care about it (i.e. inference is best done
> in some subtle and complicated way by people, not in a simple and
> stupid way by computers). Should they decide to care in the future,
> they can generate new RDF. It might be a lost opportunity and an
> interoperability risk, but so it goes - the horse has been led to
> water and it finds the water unpalatable.

I do not think that is a fair characterization.  Richard's example is
*not* opting out of machine inference.  It is merely opting out of
certain inferences that *some* applications need but others do *not*
need.  And that is as it *should* be, as it is not possible to cater to
*all* applications.

The subtle mistake that is being made repeatedly here is in assuming
that someone's data is *wrong* (or socially irresponsible) if it
conflates two things that we humans find useful to distinguish, such as
people versus web pages -- *even* if the class of applications for which
that data is intended have no need to make such a distinction!  This is
myth #4 in "Resource Identity and Semantic Extensions: Making Sense of

> >  http://www.w3.org/2001/tag/awwsw/issue57/20110531/
> >
> > In particular, I don't think the kind of 'punning' that we talked
> about (where different properties treat the given resource as being
> different kinds of thing) copes with the rdf:type property (shortened
> to 'a' in the Turtle) having two different values.
> Correct. I think that in addition to expanding all the properties,
> you'd also have to expand all the types, so that 'information resource
> defining its URI to be a person' is a subclass of Person and so on. I
> can add this to the presentation.
> > Similarly, it's really unclear in the above example whether the
> > owl:sameAs relates to the Person or the Document (until you find a 
> > description of <http://twitter.com/cygri>, which of course might be
> > a resource that is both a Document and a Person itself).
> I think it has to be the Document, at the level of sameAs, since
> otherwise you get false equations between documents that describe the
> same thing. 

No, you only get false equations if you *also* try to assert that
foaf:Document is disjoint with foaf:Person.  *Your* applications may
need to make that distinction, but that is an issue with the
*combination* of your application and Richard's data.  It is not an
issue with Richard's data per se: his data is perfectly fine for other
applications that have no need for that distinction.

> That assumes an entailment regime that can lead you to
> such conclusions... RDFS entailment can't, so as long as you stay away
> from interoperation with OWL content, sameAs doesn't mean anything in
> particular, and there's no risk of inconsistency.
> This community ought to be perfectly happy with me saying the URI
> refers to the information resource, since otherwise they'd be
> admitting that the assignment *does* matter!
> The thing to do is to get this community involved in specifying how to
> write metadata, e.g. embedded license declarations for RDF files that
> are about information resources, 

The licensing example is a *very* good one, as it aptly demonstrates the
problem that this ambiguity creates for *that* class of applications.
But I think it would be a mistake to suggest that *all* socially
responsible data should support that class of applications.

David Booth, Ph.D.

Opinions expressed herein are those of the author and do not necessarily
reflect those of his employer.
Received on Tuesday, 14 June 2011 00:39:00 UTC

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