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Re: Representing things RE: RDF and speech acts

From: <jon@hackcraft.net>
Date: Tue, 25 Nov 2003 17:46:33 +0000
Message-ID: <1069782393.3fc395792fb10@82.195.128.192>
To: "www-rdf-interest@w3.org" <www-rdf-interest@w3.org>

> actually FOAF doesn't use the same mechanism as WordNet.
> 
> My understanding of best practice is that a bare URI will often be
> understood
> to refer to the thing that gets returned - i.e. the page.

That couldn't possibly work since the thing that gets returned (the page, 
although some representations wouldn't be called "pages") depends on factors 
other than the URI.

 So if you want to
> use the wordnet entry for love, it is better to define some "definition"
> fragment for all wordnet, such as
> 
>   http://xmlns.com/wordnet/1.6/love-4#defn
> 
> and this can clearly identify anything you want, but doesn't mean "the page
> itself".
> 
> FOAF gets around the desire to do this by using a blank Node to identify a
> Person -
> 
> the person whose email address is mailto:foo@example.net
> 
> Or in RDF
> 
> <rdf:RDF xmlns="I forget right now"
>          xmlns:foaf="the foaf namespace">
> <foaf:Person>
>   <foaf:mbox rdf:resource="mailto:foo@example.net"/>
> </foaf:Person>
> </rdf:RDF>

The problem FOAF is getting around here is that there is no agreed system for 
identifying people with URIs but there is an agreed mechanism for communicating 
with people using URIs (mailto URIs) and for a large number of people there 
exists a mailto URI used by them and them alone (foaf:mbox is an 
InverseFunctionalProperty, so for any given mailto:URI only one person can have 
that as their foaf:mbox, which is not true of all mailto URIs).

There is nothing in this to say that the node has to be blank, the following is 
valid:

<rdf:RDF
  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns="http://xmlns.com/foaf/0.1/">
  <Person rdf:about="http://www.hackcraft.net/jon/">
    <mbox rdf:resource="mailto:jon@hackcraft.net"/>
  </Person>
</rdf:RDF>

This is true as long as <http://www.hackcraft.net/jon/> is a URI representing 
the person that can be uses <mailto:jon@hackcraft.net> and nobody else uses it, 
which is true. Further there is no way that the creators of FOAF can prohibit 
me from using that URI to represent myself (it's my domain I can do what I 
want) and they can't prohibit my using it with FOAF except through defining a 
document format that is not fully-featured RDF, and even then they can't stop 
me using their vocabuary in a different document format.

If you go to the URI you get a representation of me, it's a rather poor 
representation of me because I was in a modest mood when I wrote the page, but 
it is a representation of me none the less. Of course I could just return a 
404, or my server might be down, and the URI would still identify me.
 
> I think for foaf:interest it suggests you use a URI though. The indirection
> trick here is neat in that it is relatively easy to apply:
> 
> [concept] [described by] [the relevant Wordnet page]

But the page you get from dereferencing <http://xmlns.com/wordnet/1.6/Love-4> 
says that:

<http://xmlns.com/wordnet/1.6/Love-4> <http://www.w3.org/2000/01/rdf-
schema#description> "a deep feeling of sexual desire and attraction; \"their 
love left them indifferent to their surroundings\"; \"she was his first 
love\"" .
<http://xmlns.com/wordnet/1.6/Love-4> <http://www.w3.org/2000/01/rdf-
schema#subClassOf> <http://xmlns.com/wordnet/1.6/Sexual_desire> .

That is clearly a poor description of the page. It sounds closer to a 
description of erotic love to me.

The indirection is needed not if you want to identify love, but if you want to 
identify the page (about which we receive no triples at all). Which reminds me 
to put looking at <http://www.hackcraft.net/rep/rep.html> more seriously back 
onto my to do list. Anyone want to help?
Received on Tuesday, 25 November 2003 12:46:34 GMT

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