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Re: Web survey to resolve ISSUE-29 on negation

From: Birte Glimm <birte.glimm@comlab.ox.ac.uk>
Date: Sun, 9 May 2010 21:19:21 -0400
Message-ID: <o2x492f2b0b1005091819s94fc68bepbc72c48c05e974e6@mail.gmail.com>
To: Andy Seaborne <andy.seaborne@talis.com>
Cc: Lee Feigenbaum <lee@thefigtrees.net>, SPARQL Working Group <public-rdf-dawg@w3.org>
On 7 May 2010 18:28, Andy Seaborne <andy.seaborne@talis.com> wrote:
>
>
> On 07/05/2010 10:13 PM, Lee Feigenbaum wrote:
>>
>> I believe this is an error in the draft. The result should be:
>>
>> s
>> -----------------------------
>> <http://example/carol>
>> <http://example/alice>
>
> My fault - now corrected.

Ok, this now makes sense.

>>
>>> This is totally unclear to me. First, I don't understand whether we
>>> are subtracting instantiated BGPs or whether we subtract solution
>>> mappings. I think the latter and there is some compatibility
>>> condition.
>
> Would removing the DISTINCT in the example help?

I think I would actually prefer not to have distinct although the
distinct itself is not really the issue and so my preference is not
strong.

> --------------------------
> | s                      |
> ==========================
> | <http://example/carol> |
> | <http://example/carol> |
> | <http://example/alice> |
> | <http://example/alice> |
> --------------------------
>
>>
>> That's right. MINUS is a pseudo-difference operator on solution mappings.

I think I now understand it, at least all examples now make sense and
also the semantics definition below.
Cheers,
Birte

> and the definition is in the red box (needs to be moved to the SPARQL
> definition section):
>
> Minus(Ω1, Ω2) =
>    { μ | μ in Ω1 such that for all μ' in Ω2,
>    either μ and μ' are not compatible or dom(μ) and dom(μ') are disjoint }
>
>        Andy
>



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Received on Monday, 10 May 2010 01:19:57 GMT

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