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RE: [ALL] RDF/A Primer Version

From: Miles, AJ \(Alistair\) <A.J.Miles@rl.ac.uk>
Date: Wed, 25 Jan 2006 18:37:03 -0000
Message-ID: <677CE4DD24B12C4B9FA138534E29FB1D0CC4CF@exchange11.fed.cclrc.ac.uk>
To: "Pat Hayes" <phayes@ihmc.us>, "Booth, David \(HP Software - Boston\)" <dbooth@hp.com>
Cc: "Ben Adida" <ben@mit.edu>, "SWBPD list" <public-swbp-wg@w3.org>, "public-rdf-in-xhtml task force" <public-rdf-in-xhtml-tf@w3.org>

Comment on

http://www.w3.org/2001/sw/BestPractices/HTML/2006-01-24-rdfa-primer
RDF/A Primer $Id: 2006-01-24-rdfa-primer.xml,v 1.7 2006/01/24 16:43:20 adida Exp $

The example:

<html>
    <head>
        <title>Jo Lamda's Home Page</title>
    </head>
    <body>
        <p>
            Hello. This is <span property="foaf:name">Jo Lamda</span>'s
            home page.
            <h2>Work</h2>
            If you want to contact me at work, you can
            either <a rel="foaf:mbox" href="mailto:jo.lambda@example.org">email
                me</a>, or call <span property="foaf:phone">+1 777 888 9999</span>.
        </p>
    </body>
</html>

... gives the following triples (assuming that the above is the content of Jo's home page):

<http://jo-lamda.blogspot.com/> 
  foaf:name "Jo Lambda";
  foaf:mbox <mailto:jo.lambda@example.org>;
  foaf:phone "+1 777 888 9999".

What is the URI <http://jo-lamda.blogspot.com/> being used to denote? Jo? Jo's home page? Both?

How is it possible for Terri's contact software to 'extract' the 'information':

foaf:homepage = "http://jo-lamda.blogspot.com/"

... where no such triple is given in the content, unless it 'knows' to handle home pages containing RDF/A in a special way?

If the example were to be:

<html>
    <head>
        <title>Jo Lamda's Home Page</title>
    </head>
    <body>
        <p>
            Hello. This is <span property="foaf:name">Jo Lamda</span>'s
            <a rel="foaf:homepage" href="http://jo-lamda.blogspot.com/">home page</a>.
        </p>
    </body>
</html>

... it would give the additional triple:

<http://jo-lamda.blogspot.com/> foaf:homepage <http://jo-lamda.blogspot.com/>.

How does Terri's contact software handle this? How should other applications handle this?

As I understand it, if you want to use the URI <http://jo-lamda.blogspot.com/> to _indirectly identify_ Jo, you have to do something like:

_:aaa foaf:homepage <http://jo-lamda.blogspot.com/>;
  _:aaa foaf:name "Jo Lambda".

Similarly, if you want to use the URI of Jo's internet mail box <mailto:jo.lambda@example.org> to _indirectly identify_ Jo, you have to do something like:

_:aaa foaf:mbox <mailto:jo.lambda@example.org>;
  _:aaa foaf:name "Jo Lambda".

Then, because foaf:mbox is an inverse functional property (as is foaf:homepage), if it were declared that:

_:bbb foaf:mbox <mailto:jo.lambda@example.org>.

... we could arrive at the conclusion:

_:bbb owl:sameAs _:aaa.

... which in turn would lead to the conclusion:

_:bbb foaf:name "Jo Lambda".

(Is this correct?)

This was what I understood by 'indirect identification' as implemented in RDF/OWL.

To say:

<http://jo-lamda.blogspot.com/> foaf:name "Jo Lambda".

... is to use the URI <http://jo-lamda.blogspot.com/> to _directly identify_ both Jo and her home page. I.e. this is a URI collision. If both Jo's home page URI and her internet mail box URI were used to _directly identify_ Jo, you could end up drawing the conclusion that:

<http://jo-lamda.blogspot.com/> owl:sameAs <mailto:jo.lambda@example.org>.

Surely we want to avoid that? 

Cheers,

Al.
Received on Wednesday, 25 January 2006 18:37:13 UTC

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