W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > January 2002

RE: not-id-and-resource-attr & bagID

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Thu, 10 Jan 2002 15:31:38 -0000
To: "Jan Grant" <Jan.Grant@bristol.ac.uk>, "Brian McBride" <bwm@hplb.hpl.hp.com>
Cc: "RDFCore Working Group" <w3c-rdfcore-wg@w3.org>
Message-ID: <JAEBJCLMIFLKLOJGMELDCEMDCCAA.jjc@hplb.hpl.hp.com>
I found Jan's message somewhat hard to follow.

I'll not labour my disagreement with some of the assumptions about the
meaning of M&S.

In this message I will restrict my comments to bagID in an empty property
element production.

Jan:
> OK, here I'm going to refer you to Dave's WD:
>
> http://www.w3.org/TR/2001/WD-rdf-syntax-grammar-20011218/#emptyPropertyElt
>
> (that is, section 5.14)
>
[...]
>
> (with the proviso that all of idAddr, resourceAttr and bagIdAttr are not
> present at the same time. These alternatives can be enumerated)
>

Dave says "bagID cannot be used when there are no propertyAttr"

I don't understand either restiction on bagID here. In either case, for me
on my reading of M&S,a bagID unambiguously indicates the bag formed from the
reifications of the property attributes (if any) of this property element.

Hence a bagID on any otherwise empty property element generates one triple,
the type triple for the bag.

e.g.

<rdf:RDF>
  <rdf:Description rdf:ID="A">
   <rdf:value rdf:bagID="B" />
  </rdf:Description>
</rdf:RDF>

==>
<#A> <rdf:value> _:a .
<#B> <rdf:type> <rdf:Bag> .

Adding prop attrs is unproblematic:


<rdf:RDF>
  <rdf:Description rdf:ID="A">
   <rdf:value rdf:bagID="B" a:a="a" />
  </rdf:Description>
</rdf:RDF>

==>
<#A> <rdf:value> _:a .
<#B> <rdf:type> <rdf:Bag> .
_:a <a:a> "a" .
_:r <rdf:type> <rdf:Statement>.
_:r <rdf:subject> _:a .
_:r <rdf:predicate> <a:a>.
_:r <rdf:object> "a".
<#B> <rdf:_1> _:r.

------------------------

An rdf:ID on this triple either indicates the reification of the
  <#A> <rdf:value> _:a .
triple, on my preferred resolution, or indicates the identity of the object
bNode (_:a) on the current text of the syntax WD. Either way there is no
difficulty in having both a bagID and an ID.


Jeremy
Received on Thursday, 10 January 2002 10:35:19 EST

This archive was generated by hypermail pre-2.1.9 : Wednesday, 3 September 2003 09:43:53 EDT