W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > May 2001

Re: Issue rdfms-empty-property-elements

From: Dan Connolly <connolly@w3.org>
Date: Wed, 09 May 2001 11:20:21 -0500
Message-ID: <3AF96E45.FA9B2F4F@w3.org>
To: Jan Grant <Jan.Grant@bristol.ac.uk>
CC: RDFCore Working Group <w3c-rdfcore-wg@w3.org>
Jan Grant wrote:
> 
> Ok, this should be a quick one.
> http://www.w3.org/2000/03/rdf-tracking/#rdfms-empty-property-elements

indeed.

[...]
>The question is what to do with:
> 
> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>   xmlns:random="http://random.ioctl.org/#">
> 
> <random:Objecttype>
>   <random:someProperty/>
> </random:Objecttype>
> 
> </rdf:RDF>

From most XML processing APIs, this is indistinguishable
from
	<random:someProperty></random:someProperty>

That's clearly an empty literal, no?

> There seem to be three options available:
> 
> - explicitly forbid this

I don't see why; is there some inconsistency in the
way this is implemented? Oh... the problem is in
the spec: "3. (same as rule 3 above) If E is an empty element
(no content), v is the resource whose resource identifier
is given by the resource attribute of E."

That seems like a bug.

> - interpret it as having an anonymous resource as the value of the
>   property

That seems completely broken.

> - interpret it as having the null literal as the value of the property,
>   as already suggested by Jos de Roo.
> 
> (in the last two cases, we may choose to deprecate this form)
> 
> There are arguments of ostensibly equal value for choosing either of
> the latter two options; I'd lean towards Jos' point of view: that the
> interpretation of
> 
>   <random:someProperty/>
> 
> be a property arc pointing to the null literal;

(null? that's not different from empty, is it?)

Yes, that's how I think I implemented it...
(copy Jan's test case to a file... testing...)
Oops! the RDF parser in TimBL's swap stuff doesn't
grok at all. But I think that's just a bug.

Anyway... I'm attaching Jan's example (and cloaking
it as HTML) to make it accessable by HTTP from
the WG archive.


-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/

Received on Wednesday, 9 May 2001 12:20:32 EDT

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