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Re: Question about duplicate triples

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Tue, 31 Jul 2012 17:10:10 +0100
Message-ID: <50180362.6040502@epimorphics.com>
To: public-rdf-dawg-comments@w3.org, David Booth <david@dbooth.org>


On 31/07/12 15:36, David Booth wrote:
> On Mon, 2012-07-30 at 18:18 -0400, David Booth wrote:
>> Suppose I LOAD a single file of NTriples into a named graph foo:, and
>> that file contains some duplicate triples such as:
>>
>>    _:bnode <http://example/ppp> <http://example/vvv> .
>>    _:bnode <http://example/ppp> <http://example/vvv> .
>>    _:bnode <http://example/ppp> <http://example/vvv> .
>>
>> According to the RDF Semantics, an RDF graph is a *set* of triples.
>> Hence, AFAIK the above file represents an RDF graph containing *one*
>> triple, and the graph is lean.
>>
>> If I then query that named graph as follows, how many solutions should I
>> get?
>>
>>    SELECT * WHERE { GRAPH foo: { ?s ?p ?v } }
>>
>> Is the SPARQL server permitted to return more than one solution (i.e.,
>> duplicates) in this case?
>>
>> I am aware of the DISTINCT keyword, but I always understood it as being
>> intended for situations where the query could generate multiple
>> candidate solutions, which is not the situation in this case.  It seems
>> a little weird if a SPARQL server might return multiple solutions in
>> this case, but would it still be conforming to the SPARQL spec if it
>> did?
>
> To further elaborate, if I issue this query in the above situation
>
>    SELECT (COUNT(*) AS ?count) WHERE { GRAPH foo: { ?s ?p ?v } }
>
> would any number greater than zero be a conforming result for ?count ?
>
> Or in a more general sense, if DISTINCT is not used, are the only
> semantically distinguishable values for COUNT: (a) zero; and (b) at
> least one?

Please see

http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/2012Jul/0029.html

Please consider using the mailing list public-sparql-dev@w3.org for 
general questions.  It allows for general discussion.

	Andy

>
>
>
Received on Tuesday, 31 July 2012 16:10:42 GMT

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