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Re: InverseFunctional properties are the new URI?

From: Dan Brickley <danbri@w3.org>
Date: Thu, 29 Jul 2004 15:46:37 -0400
To: Phil Dawes <pdawes@users.sf.net>
Cc: www-rdf-interest@w3.org
Message-ID: <20040729194637.GJ31835@homer.w3.org>

* Phil Dawes <pdawes@users.sf.net> [2004-07-29 17:52+0000]
> 
> Hi All,
> 
> I've noticed that some RDF specs (including FOAF and DOAP) use
> inverseFunctional properties instead of URIs to identify instance
> resources. 
> 
> I can see an instant benefit in doing this - end users don't need to
> worry about the problems of minting URIs, maintaining them etc..
> 
> Is this the way RDF is going - URIs for the schema, BNodes with
> InverseFunctional properties for the instancedata?
> What are the consequences?

I think we'll always need both. 

In FOAF I've tried to be pragmatic. When "what is 'the' URI for a
person" silliness was holding up deployment, FOAF encouraged an 
emphasis on reference-by-description techniques. OWL subsequently gave
us a way of expressing simple reference-by-description strategies in a 
machine readable way. But FOAF doesn't rule out the possibility of their 
being URIs for people, companies, etc. It just doesn't let the current 
lack of such things get in the way.

Rob McCool and Guha in their TAP work take a similar line, advocating 
reference-by-description as a useful strategy for merging Web data.
http://tap.stanford.edu/tap/rbd.html
http://tap.stanford.edu/sw002.html

I think in the early days of RDF there was something of a fairytale
quality to the way URIs were perceived - basically a myth that all 
interesting and description-worthy things will have well-known URIs.
FOAF and reference-by-description in general shouldn't be taken as an
attack on URIs as such, but as advocacy that other techniques are 
useful too, and that we can write applications that figure out 
common references without all parties necessarily sharing the same URIs 
or even identifying expressions.

All that said, we've a long way to go before all RDF toolkits support 
InverseFunctional-based identity reasoning "out of the box"...

Dan
Received on Thursday, 29 July 2004 15:46:38 UTC

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