Am Montag, den 25.05.2009, 17:48 +0000 schrieb Seaborne, Andy:
> Simon/Eric - you gave do you have examples where either MINUS or EXISTS can not easily be used where EXISTS or MINUS can?
>
> The distinguishing example is helpful - seem to me that MINUS needs a slightly artificial form to introduce ?name to be set-compatible with the preceding pattern. But is this an artefact of the example and is there a counter example of EXISTs having to be slightly artificial?
>
> http://www.w3.org/2009/sparql/wiki/index.php?title=Design:Negation#Distinguish_MINUS_from_UNSAID
I don't think there are cases, which can not be expressed using one of
the forms: EXISTS can be translated into MINUS by extending the pattern,
if necessary. However, MINUS really is a bit ugly in many cases.
> > In addition, I still think that EXISTS without FILTER around are a bit
> > confusing, esp. if the next clause is OPTIONAL {...}.
>
> I'm tending to both forms although underneath raw EXISTs because I thing using iut on its own is going to be common. Internally, it behaves just like a FILTER which is not moved to the end of a BGP.
I think FILTER better captures the intended semantics. I am not sure,
whether an order dependent inline form is intuitive. On the other hand,
aesthetically I like it better. :) Why not completely translate it into
a FILTER, including a reordering?
Cheers,
Simon
--
Simon Schenk | ISWeb | Uni Koblenz
http://isweb.uni-koblenz.de
http://www.uni-koblenz.de/~sschenk
Received on Tuesday, 26 May 2009 10:11:35 UTC