- From: Eric Prud'hommeaux <eric@w3.org>
- Date: Mon, 27 Jul 2009 17:03:30 -0400
- To: SPARQL Working Group <public-rdf-dawg@w3.org>
- Cc: "Seaborne, Andy" <andy.seaborne@hp.com>
ISSUE-29
I believe this definition of Minus in SPARQL algebra is practical for all use cases:
Definition: Minus
Let Ω1 and Ω2 be multisets of solution mappings. We define:
Diff(Ω1, Ω2, expr) = { μ | μ in Ω1 such that for all μ′ in Ω2, μ and μ′ are not compatible }
card[Diff(Ω1, Ω2, expr)](μ) = card[Ω1](μ)
which is the same as Diff (Ω1, Ω2, true)
http://www.w3.org/TR/rdf-sparql-query/#defn_algDiff
--
-eric
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Received on Monday, 27 July 2009 21:04:13 UTC