- From: Axel Polleres <axel@polleres.net>
- Date: Tue, 13 Aug 2013 21:10:32 +0200
- To: David Booth <david@dbooth.org>
- Cc: Quentin Reul <Quentin.H.Reul@gmail.com>, semantic-web@w3.org, public-rdf-wg@w3.org, public-sparql-dev@w3.org
> [[
> The group pattern:
> { }
> matches any graph (including the empty graph) with one solution that does not bind any variables.
> ]]
This only means that upon
SELECT ?G WHERE { GRAPH ?G {} }
also empty named graphs should be returned, which would not be the case for
SELECT ?G WHERE { GRAPH ?G { ?S ?P ?O } }
Obviously, this makes a difference for all graph stores that support empty named graphs.
So, to my understanding at least, this is not a bug in the spec.
HTH,
Axel
On 13 Aug 2013, at 20:21, David Booth <david@dbooth.org> wrote:
> Hi Axel,
>
> That doesn't work in Sesame 2.7.1 at least, apparently because ?G is not bound, even though there is one solution. The SPARQL 1.1 spec says:
> http://www.w3.org/TR/sparql11-query/#emptyGroupPattern
> [[
> The group pattern:
> { }
> matches any graph (including the empty graph) with one solution that does not bind any variables.
> ]]
>
> Is this a bug in the spec?
>
> David
>
> On 08/13/2013 11:48 AM, Axel Polleres wrote:
>> Hi Quentin,
>>
>> how about just
>>
>> SELECT ?G WHERE { GRAPH ?G {} }
>>
>> (no need to dump all triples, if the only concern is which ?G exist)
>>
>> BTW, public-sparql-dev@w3.org may be the list you wanted to use.
>>
>> best,
>> Axel
>>
Received on Tuesday, 13 August 2013 19:11:03 UTC