- From: Andy Seaborne <andy.seaborne@epimorphics.com>
- Date: Tue, 21 Dec 2010 10:31:53 +0000
- To: Axel Polleres <axel.polleres@deri.org>
- CC: Steve Harris <steve.harris@garlik.com>, SPARQL Working Group <public-rdf-dawg@w3.org>
On 20/12/10 17:23, Axel Polleres wrote: > Steve, > > I added a new use case pp16 along the lines you suggest, see details below. > > On 20 Dec 2010, at 16:46, Steve Harris wrote: > >> I think pp14 would be more enlightening if the pp14.ttl included a disconnected foaf:knows graph, and some triples using another predicate. Something like: >> >> @prefix :<http://example.org/> . >> @prefix foaf:<http://xmlns.com/foaf/0.1/> . >> >> :a foaf:knows :b . >> :b foaf:knows :c . >> :d foaf:knows :e . >> :f foaf:name "test" . >> :a foaf:homepage :h . >> >> Even after Axel's proposed changes I find the wording a bit impenetrable, though admittedly I haven't had time to study the algebra. >> >> Axel, can you tell mw what results you'd expect from pp14.rq with that data? >> > > your data returns, according to my understanding of the algebra: > > ------------------- > | X | Y | > =================== > | :a | :a | > | :a | :b | > | :a | :c | > | :b | :b | > | :b | :c | > | :c | :c | > | :d | :d | > | :d | :e | > | :e | :e | > | :f | :f | > | :h | :h | > | "test" | "test" | > ------------------- > > I would, BTW, rather keep the simple use case pp14 "as is", and added a more complex one having your extension, as well as > duplicate paths and cycles as a separate new use case: > > @prefix :<http://example.org/> . > @prefix foaf:<http://xmlns.com/foaf/0.1/> . > > :a foaf:knows :b . > :b foaf:knows :c . > :a foaf:knows :c .<-- duplicate path > :d foaf:knows :e . > :e foaf:knows :f . > :f foaf:knows :e .<-- cycle > :f foaf:name "test" . > :a foaf:homepage :h . > > I am not sure about the cycle handling ATM, so I can only give the result from ARQ (which is what I checked in under pp16.srx for now): Looks like a bug to me. I want to rewrite the path evaluation to follow the spec - it predates the spec at the moment. Andy
Received on Tuesday, 21 December 2010 10:32:33 UTC