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Re: Typos in SPARQL 1.1 Query

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Thu, 15 Dec 2011 15:58:36 +0000
Message-ID: <4EEA192C.80708@epimorphics.com>
To: Olivier Corby <olivier.corby@inria.fr>
CC: SPARQL Working Group <public-rdf-dawg@w3.org>


On 07/12/11 14:38, Olivier Corby wrote:
>> eval(D(G), OneOrMore(x:term, path, vy:var)) =
>> Let X = eval(x, path)
>> Let R = the empty multiset
>> For n in X
>> Let V = {}
>> ALP(n, path, R, V)
>> End
>> result is R
>>
>>
>> I don't think so. V is the set of nodes visited and should carry
>> across calls to ALP for each possible next step in set X.
>>
>> In OneOrMore the form of ALP being called is the main worked function
>> and V is an accumulator of visited nodes.
>>
>> In ALP, ALP(x:term, path) passes in an empty set to the main worker
>> function. This is the route taken by ZeroOrMore. OneOrMore calls the
>> main worked function directly.
>>
>> Do you have an example of the difference as you see it?
>
> My understanding (?) is that for each value of n in the loop, V is empty.
> Because, according to the definition of ALP, V is empty when returning
> from ALP(n, path, R, V)
> So it is clearer (to me) if it is explicit in the call.
> It would be even clearer with :
>
> ALP(n, path, R, {})
>
> Am I missing something here ?

Don't think so.

Change made.

	Andy

>
> Olivier
>
>
Received on Thursday, 15 December 2011 15:59:05 GMT

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