- From: Seaborne, Andy <andy.seaborne@hp.com>
- Date: Mon, 02 Oct 2006 11:06:06 +0100
- To: Bijan Parsia <bparsia@cs.man.ac.uk>
- CC: RDF Data Access Working Group <public-rdf-dawg@w3.org>
Bijan Parsia wrote: > Sorry to be late, but there was some confusion about what was going > on and then I hit the class part of the week. > > I think the status part should point to the issues list. > > """Costs: Tableau-based reasoners (at least, the Pellet Demo example > 7) rely on the current, more expressive semantics to match > implications that are not in a materializable RDF graph.""" > > No. Pellet uses BNodes as syntax for non-distinguished variables, as > that's what we were told was the likely syntax for non-distinguished > variables in SPARQL/DL. The semantics of *all* variables in SPARQL/ > RDF is semi-distinguished. I'd be interested in tracing this back sometime. Who told you/Pellet and does the working group have a record of it? I'd find it useful in bring some of the themes together as there is a lot of material scattered over the email archive. > I thought the alternative proposal (e.g., from conversation with > Jeen, Jorge and others) was to *drop* BNodes in triple patterns. That > does solve all the problems of scope, meaning etc., but it means that > certain combinations of the axes of distinguishedness will be harder > to specify (but heck, we can always introduce syntax later). > > """@@ Now we are in CR, shouldn't this be deleted? Need chair's > permission. > The working group decided on this design and closed the disjunction > issue without reaching consensus. The objection was that adding UNION > would complicate implementation and discourage adoption. If you have > input to this aspect of the SPARQL that the working group has not yet > considered, please send a comment to public-rdf-dawg-comments@w3.org.""" > > I would like that to be deleted because it's confusing on several > levels (e.g., why doesn't it apply in optional?) I don't particularly > care that it'd done before pub, but it seems an easy enough move. I > mean, it doesn't *change* anything! This text does seem out of date: the objection from DaveB was withdrawn and I can't find a record of any other (I just checked with Steve). http://www.w3.org/2001/sw/DataAccess/issues#disjunction It is confusing. But I'd like the chair's permission as confirmation. Andy > > """Current conventions for DESCRIBE return an RDF graph without any > specified constraints. Future SPARQL specifications may further > constrain the results of DESCRIBE, rendering some currently valid > DESCRIBE responses invalid. As with any query, a service may refuse > to serve a DESCRIBE query."""" > > I have other comments, both editorial and substantial, but they are > for post publication, I think. > > Cheers, > Bijan. >
Received on Monday, 2 October 2006 10:06:44 UTC