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RE: RDF's binary nature

From: Danny Ayers <danny666@virgilio.it>
Date: Thu, 19 Jun 2003 19:03:37 +0200
To: "Tom Reilly" <treilly@macromedia.com>, <www-rdf-interest@w3.org>
Message-ID: <BKELLDAGKABIOCHDFDBPAEKBDBAA.danny666@virgilio.it>

Hi Tom,

RDF statements aren't binary, they're tertiary (triples of subject,
predicate, object), and resources most certainly can have more than one
value for a given property. I couldn't find a particularly clear example
like yours in the Primer [1] (is there one? there certainly should be), I
could only find this way down in the description of containers :

exstaff:Sue exterms:publication ex:AnthologyOfTime .
exstaff:Sue exterms:publication ex:ZoologicalReasoning .
exstaff:Sue exterms:publication ex:GravitationalReflections .

Here the example is saying : Sue has written "Anthology of Time",
"Zoological Reasoning", and "Gravitational Reflections". Same subject and
property with three different objects. As legal as it gets ;-) Note also
that Sue might have written other things which might be expressed elsewhere
(e.g. in other RDF files) - there is nothing here to say that this is all
she's written.


[1] http://www.w3.org/TR/rdf-primer

> -----Original Message-----
> From: www-rdf-interest-request@w3.org
> [mailto:www-rdf-interest-request@w3.org]On Behalf Of Tom Reilly
> Sent: 19 June 2003 18:00
> To: 'www-rdf-interest@w3.org'
> Subject: RDF's binary nature
> Since I first started reading about RDF I assumed its binary
> nature implied that you couldn't have a resource with more
> than one value for the same property, ie that this wasn't legal:
> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>          xmlns="http://www.foo.org/bar#">
>   <foo>
>     <bar>baz</bar>
>     <bar>boo</bar>
>   </foo>
> </rdf:RDF>
> But apparently it is (it validates with the RDF Validation Service
> and I've encountered real world examples of the same basic structure)
> and when I think about it there's no real basis for such an assumption.
> I was hoping someone could verify that this is in fact valid and possibly
> explain why this is legal when we have bags.  The fact that there are
> no examples of this in any of the RDF specs I've read (that I can remember
> at least) could be seen as a little misleading.
> I'm trying to come up with a simple RDF API and the API could be much
> simpler if this wasn't the case.  I also realize that this structure
> is very common in other XML dialects and disallowing it would create a
> barrier to converting them to RDF.
> Also if I have:
>     <bar>baz</bar>
>     <bar>baz</bar>
> instead I'm making two distinct but otherwise equivalent statements right?
> Thanks in advance...
Received on Thursday, 19 June 2003 13:07:14 UTC

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