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anonymous abouts (blank node creation)

From: Ivan Herman <ivan@w3.org>
Date: Wed, 18 Jul 2007 12:56:12 +0200
Message-ID: <469DF1CC.1040609@w3.org>
To: RDFa <public-rdf-in-xhtml-tf@w3.org>
Some of the issues in the past days made me thing a bit. I refer here to
 issues like


One of the problems we are fighting with is when to generate a new blank
node and how...

I guess we will have something special for about values along the lines
of turtle for blank nodes, right? about="_:blabla" means a blank node
with nodeId (to use the RDF/XML terminology) "blabla". But what is the
meaning of about="_:". Well, mentally, I could say that this means a
blank node hose nodeId I do not care about, just let the system choose
whatever this wants.

What this means is that if I say

<div property="a:b" about="_:">blabla</div>

that would yield

[ a:b "blabla" ]

Or, if there are more things in <div> the blank node would act as a
common subject, because the same rules for @about would apply.



Mark proposed that

<div instanceof="foaf:Person">

would automatically create a blank node and instanceof would apply to
that. In fact, we could say that the real code here is:

<div instanceof="foaf:Person" about="_:">

in which case the rule from Mark simply come from our usual rules,
without any exception to instanceof (compared to the usage of @rel, ie,
to what the attribute applies to).

The other issue was to create a list of anonymous blank nodes. Well

<ul instanceof="rdf:List">
<li about="_:" instanceof="foaf:Person" property="foaf:name">A</li>
<li about="_:" instanceof="foaf:Person" property="foaf:name">B</li>

would exactly do it. Note that if of the authors have his/her own
resource, than

<ul instanceof="rdf:List">
<li about="_:" instanceof="foaf:Person" property="foaf:name">A</li>
<li about="http://www.a.b.c" instanceof="foaf:Person"

would of course do it, and keep it very symmetrical.

We already have a rule on the creation of 'empty' nodes, ie

<div rel="a:b">....</div>

means setting a new blank node. We could keep that rule, too, I do not
think it would lead to any harm...

This is really just an uncooked idea, may be absolute rubbish. But maybe
it is worth looking at it...



Ivan Herman, W3C Semantic Web Activity Lead
URL: http://www.w3.org/People/Ivan/
PGP Key: http://www.cwi.nl/%7Eivan/AboutMe/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf

Received on Wednesday, 18 July 2007 10:56:10 UTC

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