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Re: SOURCE in N3QL

From: Jos De_Roo <jos.deroo@agfa.com>
Date: Sat, 25 Sep 2004 20:55:43 +0200
To: ""Seaborne@smtp2.agfa.be, Andy" <andy.seaborne" <andy.seaborne@hp.com>, "Eric Prud'hommeaux" <eric@w3.org>
Cc: public-rdf-dawg@w3.org
Message-ID: <OF2939AAC1.96517446-ONC1256F1A.0065E414-C1256F1A.006804B3@agfa.com>

Andy,
Eric,

I made 2 test cases

1/
data:  http://eulersharp.sourceforge.net/2004/04test/D1.n3
query: http://eulersharp.sourceforge.net/2004/04test/D1Q.n3
gives: http://eulersharp.sourceforge.net/2004/04test/D1E.n3

which is an empty answer
because the bnodes in D2.n3 could be some different things


2/
data:  http://eulersharp.sourceforge.net/2004/04test/D2.n3
query: http://eulersharp.sourceforge.net/2004/04test/D2Q.n3
gives: http://eulersharp.sourceforge.net/2004/04test/D1E.n3

which is 2 answers
because the bnodes came from the same graph D2.n3
and so they unify

at least that is my current understanding about relabeling
bnodes and unification :)


jos

-- 
Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/




"Seaborne, Andy" <andy.seaborne@hp.com>
25/09/2004 17:01

 
        To:     Jos De_Roo/AMDUS/MOR/Agfa-NV/BE/BAYER@AGFA, "Eric Prud'hommeaux" 
<eric@w3.org>
        cc: 
        Subject:        SOURCE in N3QL


Jos,

I tried to explain this to Eric in an email and I have a question:

> well, I thought that
>
>   SELECT ?x ?y ?n
>   WHERE
>     (?x foaf:knows ?y)
>     SOURCE <D2.n3> (?x foaf:age ?n)
>     ...
>
> nicely maps to
>
>   []
>   q:select {(?x ?y ?n) a q:Answer};
>   q:where  {?x foaf:knows ?y.
>             <D2.n3>.log:semantics log:includes {?x foaf:age ?n}}.
>             ...

?x is a bNode.

My thought:

----
The query assumes that <D2.n3> has the same bNode as the outer context "?x
foaf:knows ?y" so there may be there is an assumption that the global
graph is the RDF merge of the named components.
----

Is my thought right or wrong or misguided?

Which ever, this is beginning to give a possible theoretical foundation
for SOURCE.

Andy
Received on Saturday, 25 September 2004 18:56:29 GMT

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