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Re: property paths three more test cases pp13, pp14, pp15

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Tue, 21 Dec 2010 10:31:53 +0000
Message-ID: <4D108219.3070601@epimorphics.com>
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 GMT

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