- From: Seaborne, Andy <andy.seaborne@hp.com>
- Date: Mon, 29 Jun 2009 14:21:34 +0000
- To: "public-rdf-dawg@w3.org" <public-rdf-dawg@w3.org>
> -----Original Message----- > From: public-rdf-dawg-request@w3.org [mailto:public-rdf-dawg- > request@w3.org] On Behalf Of Simon Schenk > Sent: 29 June 2009 10:36 > To: public-rdf-dawg@w3.org > Subject: UNSAID vs MINUS > > ACTION-32 http://www.w3.org/2009/sparql/track/actions/32 > > To revive the discussion on negation, I would like to point you to the > overview of options for implementation at: > http://www.w3.org/2009/sparql/wiki/Design:Negation > > In particular, binary operators vs. FILTER expressions, and set based > MINUS in SeRQL vs UNSAID are discussed. Note that MINUS in SeRQL != > MINUS in Mulgara (?), which has the same semantics as UNSAID. > > Cheers, > Simon Good time to revive it. (I reorganised the page end of Friday - didn't remove any text intentionally but I put the two options in separate sections. I generally called it NOT EXISTS.) To make progress on this, let's take it in two steps. 1/ Decide on UNSAID vs Set-MINUS, that is resolve to explore one design in depth 2/ Then take as a sub-issue of NOT EXISTS as to have a graph operator and/or a FILTER expression. I propose we adopt the UNSAID/NOT EXISTS design. The Set-MINUS seems to have no advantages because it is equivalent to an NOT EXISTS form, but requires each side to be a set, which would need to be worked through the rest of the language. On the second part, I found it to be no more work as the graph operator is the introduction of algebra-level filter. Andy
Received on Monday, 29 June 2009 14:22:30 UTC