- From: Miles, AJ \(Alistair\) <A.J.Miles@rl.ac.uk>
- Date: Wed, 25 Jan 2006 18:37:03 -0000
- 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