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RE: Lee's feature proposal

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Tue, 5 May 2009 09:37:00 +0000
To: Axel Polleres <axel.polleres@deri.org>, Lee Feigenbaum <lee@thefigtrees.net>
CC: SPARQL Working Group <public-rdf-dawg@w3.org>
Message-ID: <B6CF1054FDC8B845BF93A6645D19BEA362D156730F@GVW1118EXC.americas.hpqcorp.net>
> [edit] Negation
> 
> Question: For those arguing strongly for it? Would you be fine with
> seeing this as part of surface syntax?

What is the proposal here?

> 
> Rationale: I think it is easy enough to specify, but strictly speaking,
> a redundant feature.

I would like to see the specification to understand that.

Try testing for the absence of <s> <p> <o> using OPTIONAL/!BOUND, which relies on a free variable so it has to be introduced and then removed.  (That one is easier with a pattern and a filter of != 's.)  So if there is a translation, it is non-trivial.

It can't just be a sub-ASK-query because you want the negation of the answer unless the ASK is in a FILTER - which is effectively just moving the negation work into the subQuery feature as discussed and then we have to consider the interaction of BGP and filters. It does not make it easier, it's just been moved around.

> [edit] FullText
> 
> Question: Is a surface syntax for regular expression sufficient, or at
> least could we reach consensus on treating only that?

It is not surface syntax for a regex.

> [edit] SurfaceSyntax
> 
> Question1: What would this involve?
> 
> Question2: How should we prioritize subfeatures?
> 

Surface syntax is in danger of becoming a magic dumping ground!

	Andy

Received on Tuesday, 5 May 2009 09:38:19 GMT

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