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Re: Duplicate triples Re: RDF Graph

From: Paul Gearon <pag@tucanatech.com>
Date: Sat, 9 Oct 2004 16:32:26 +1000
Message-Id: <FCB0192E-19BC-11D9-A688-000D93B0E8B6@tucanatech.com>
To: www-rdf-interest@w3.org


On 07/10/2004, at 7:50 AM, Charles McCathieNevile wrote:
> On Wed, 6 Oct 2004, Jan Algermissen wrote:
>
>> this is likely to be a silly question, but I seem to be unable to 
>> parse
>> the anser from the RDF Recommendations.
>>
>> "An RDF graph, or simply a graph, is a set of RDF triples."
>> (from RDF Semantics, 0.3 "Graph Definitions")
>>
>> Since the graph is a set it does not contain duplicate triples, yes?
>
> I recall a discussion on this topic recently. I believe that someone 
> who
> knows the spec better than I do said the formal definition doesn't 
> prohibit
> redundant triples, so a conformant program would not necessarily delete
> them...

I can't comment on the formal spec on this specific point, as I haven't 
checked it [1], but I think it worth mentioning two related points.

First, most (all?) RDF databases do not store redundant statements.  I 
know that Kowari certainly doesn't.

Second, collections use a cons list, which seem especially designed to 
avoid creating duplicate statements if the same item is included twice. 
  Having worked with these for a while, I can't think of any reason for 
this construction except that RDF is trying to avoid duplicate 
statements in an environment which does not permit them.

So I would just assume that duplicate statements are dropped.  If 
you're concerned, then check the system you're using before going 
proceeding too far.

[1] I'm going to be spending an hour or two looking for this now, 
aren't I?  :-(

Regards,
Paul Gearon

Software Engineer
Tucana Technologies
http://www.tucanatech.com

Catapultam habeo. Nisi pecuniam omnem mihi dabis, ad caput tuum saxum
immane mittam.
(Translation from latin: "I have a catapult. Give me all the money,
or I will fling an enormous rock at your head.")
Received on Saturday, 9 October 2004 06:33:07 GMT

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