- From: Steve Harris <swh@ecs.soton.ac.uk>
- Date: Thu, 21 Aug 2008 17:03:21 +0100
- To: Axel Polleres <axel.polleres@deri.org>
- Cc: Lee Feigenbaum <lee@thefigtrees.net>, public-sparql-dev@w3.org, public-lod@w3.org
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) ?
- Steve
Received on Thursday, 21 August 2008 16:04:18 UTC