- From: Axel Polleres <axel.polleres@deri.org>
- Date: Thu, 21 Aug 2008 17:45:01 +0100
- To: Steve Harris <swh@ecs.soton.ac.uk>
- CC: Lee Feigenbaum <lee@thefigtrees.net>, public-sparql-dev@w3.org, public-lod@w3.org
Steve Harris wrote:
> On 21 Aug 2008, at 16:51, Axel Polleres wrote:
>
>>
>> Tackling the question from the more theoretical side,
>> I like non-monotonic SPARQL queries like the ones modeling set
>> difference.
>>
>> E.g.
>> "Give me all persons *without* an email address" in a certain FOAF graph.
>>
>>
>> i) It is already folklore, that you can do that with using the
>> !bound() filter outside an optional, i.e.
>>
>> SELECT ?X
>> FROM G
>> WHERE { ?X a foaf:Person
>> OPTIONAL { ?X foaf:mbox ?M}
>> FILTER (! bound(?X) ) }
>
> Shouldn't that be !bound(?M) ?
yup, sorry, typo ... The really nasty trick was anyway the second one
as Lee already remarked ;-)
> - Steve
--
Dr. Axel Polleres, Digital Enterprise Research Institute (DERI)
email: axel.polleres@deri.org url: http://www.polleres.net/
Everything is possible:
rdfs:subClassOf rdfs:subPropertyOf rdfs:Resource.
rdfs:subClassOf rdfs:subPropertyOf rdfs:subPropertyOf.
rdf:type rdfs:subPropertyOf rdfs:subClassOf.
rdfs:subClassOf rdf:type owl:SymmetricProperty.
Received on Thursday, 21 August 2008 16:53:20 UTC