- From: Andy Seaborne <andy.seaborne@talis.com>
- Date: Fri, 07 May 2010 23:28:03 +0100
- 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 UTC