W3C home > Mailing lists > Public > public-rdf-dawg@w3.org > April to June 2010

Re: Web survey to resolve ISSUE-29 on negation

From: Andy Seaborne <andy.seaborne@talis.com>
Date: Fri, 07 May 2010 23:28:03 +0100
Message-ID: <4BE493F3.7010404@talis.com>
To: Lee Feigenbaum <lee@thefigtrees.net>
CC: Birte Glimm <birte.glimm@comlab.ox.ac.uk>, SPARQL Working Group <public-rdf-dawg@w3.org>


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.

>
>> 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?

--------------------------
| 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.

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
Received on Friday, 7 May 2010 22:28:12 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 16:15:42 GMT