- From: <jos.deroo@agfa.com>
- Date: Thu, 7 Apr 2005 01:30:34 +0200
- To: connolly@w3.org
- Cc: RDF Data Access Working Group <public-rdf-dawg@w3.org>
Dan Connolly wrote: > On Wed, 2005-04-06 at 22:13 +0200, jos.deroo@agfa.com wrote: >> picking out just one case.. (have tested 11 cases a while back) >> >>> 10 Namespace >>> Return all resources whose namespace starts with >>> "http://aifb.uni-karlsruhe.de/". >>> >>> seems to have a typo in the question... >>> missing www. >>> >>> select ?R where >>> { ?R ?x ?y. >>> FILTER regex(str(?R), "http://www.aifb.uni-karlsruhe.de/") >>> } >> >> why not simply >> >> SELECT ?R >> WHERE {?R a rdfs:Class; >> log:uri ?S. >> ?S str:matches "http://www\.aifb\.uni-karlsruhe\.de/.*"} > > That basically involves changing the way DataSets and background > graphs work so that they always include "axiomatic" triples > such as > <http://www.aifb.uni-karlsruhe.de/> log:uri > "http://www.aifb.uni-karlsruhe.de/". > and > "a" str:matches "a". > > That was not a popular design when it was discussed in Helsinki > under issue useMentionOp > http://www.w3.org/2001/sw/DataAccess/ftf4.html#itemumop > <- http://www.w3.org/2001/sw/DataAccess/issues#useMentionOp > > Let's see... no, you weren't there for that one. You might > want to look over the record of that item and see if the > rationale/discussion there satisfies you. (I think I meant > to abstain but was too busy chairing to get my abstention > recorded.) OK, I read record and would certainly have liked the discussion (but had other f2f's at that time) and all I can really add is that we use that design of "treating mathematical inferences like RDFS and other inferences" since 5 years it really works. > If not, you can ask to re-open the issue. An implementation can convert pieces of WHERE triple patterns into certain internal (FILTER) expressions and they could behave much like traditional programming language expressions and I think it is best to keep that for the implementation instead of prescibing it (just being delarative is fine). Also given the position below, I would ask to re-open and drop FILTER. >> or some such (I don't have enough regex experience) >> >> >> I'm even more convinced after reading >> http://www.w3.org/2005/03/position2.html >> >> [[ >> Built-in Functions and operators: Use RDF Properties >> >> ... All this speaks against built-in functions being >> brought out as special syntax, and supports the use of >> RDF properties for them. >> ]] > > That's new information since the Helsinki meeting, I suppose. very much indeed and since http://www.ilrt.bris.ac.uk/discovery/chatlogs/swig/2005-03-19.html#T16-32-44 > Another thing that's sorta new information is that triple > patterns can have literal subjects. > > I'm not yet convinced the issue should be re-opened, but > everything is negotiable. > >> The point is also about that separate FILTER, I'm not >> convinced at all and basically a query is already a >> filter rule >> >> {where-triple-pattern} => {construct-or-select-triple-pattern} >> >> I just don't see the benefit of having FILTER in filter.. > > FILTER expressions behave much more like traditional programming > language expressions. While there are some "unknown" cases in > the corners, most expressions are closed over negation, unlike > triple patterns. > > Oops... I slipped into arguing... I really shouldn't do much > of that for issues that are closed. true > -- > Dan Connolly, W3C http://www.w3.org/People/Connolly/ > D3C2 887B 0F92 6005 C541 0875 0F91 96DE 6E52 C29E -- Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/
Received on Wednesday, 6 April 2005 23:30:42 UTC