Re: Simple example of need for negation operator

Hi Lee,

OK, we'll try sparql dev, as long as this is a how to, rather than a "can't
done".  But it looks to me like
your query returns no bindings if an article does not have a timetag.  I
say this because of the {?a ex:timetag ?maxtime} clause
that comes before the OPTIONAL.  But in that case, it should return
the article.  Can you fix this, or is it not expressible after all?

> In SPARQL, this query is (unedited, untested):
> FROM :model
>   ?a rdf:type ft:article ; ex:timetag ?maxtime .
>   OPTIONAL { ?a ex:timetag ?othertime . FILTER(?othertime > ?maxtime) }
>   FILTER (!bound(?othertime) && ?maxtime > '')
> }
> Original target:

FROM model
     (?a rdf:type ft:Article) AND
     UNSAID ((?a ex:timetag ?time) AND
                   (?time > $NOW))

Robert MacGregor
Chief Scientist
Siderean Software, Inc.
Mobile: 310-469-2810

Received on Tuesday, 11 December 2007 07:09:44 UTC