- From: Seaborne, Andy <andy.seaborne@hp.com>
- Date: Thu, 10 Mar 2005 16:30:49 +0000
- To: Steve Harris <S.W.Harris@ecs.soton.ac.uk>
- Cc: 'RDF Data Access Working Group' <public-rdf-dawg@w3.org>
Steve Harris wrote: > On Sun, Mar 06, 2005 at 04:58:16 +0000, Andy Seaborne wrote: > >>== 4 == Syntactic support for reification >> >>Some people use reification and use it a lot - some people use named >>graph-like approaches and avoid reification - most people just don't use >>either. > > > The others seem good, and I have no opinion on this... In progress. I have put this in and have a @@ToDo@@ to explain it in rq23. Also ?id << ?s ?p ?o >> ?id rdf:subject ?s ?id rdf:pedicate ?p ?id rdf:object ?o Also x:z << ?s ?p ?o >> x:z rdf:subject ?s x:z rdf:pedicate ?p x:z rdf:object ?o The underlying concept is that << ?s ?p ?o >> expands: [ rdf:subject ?s ; rdf:predicate ?p ; rdf:object ?o ] so it is _:a rdf:subject ?s _:a rdf:pedicate ?p _:a rdf:object ?o for some freshly minted bNode _:a (RDF collections are much the same). There can be a predfined subject which is how "?id << ?s ?p ?o >>" works. If you want to experiment, you can parse/print such queries with ARQ from CVS. There will be a collection of cryptic queries to test parsing but I haven't though of a way to test the parsing outcome (I print in a canonical debugging form and look at the moment). > > >>== 5 == Sorting/Grouping <snip/> > >>== 6 == Optionals and order dependencies. >> >>The alternatives I think if or know about are (briefly): >> >> A/ An order rule that states variables must be used in fixed >> patterns before optionals if possible. We can either make >> a query that does not do this illegal, execute in this >> canonical order or leave to implementations. > > > I have a preference for this. Currently I process all the non-OPTIONAL > blocks, then all the optionals in order, so I have a preference for doing > that :) OK - hearing no other input - I'll try for that approach. > > - Steve > Andy
Received on Thursday, 10 March 2005 16:29:55 UTC