- From: Lee Feigenbaum <lee@thefigtrees.net>
- Date: Mon, 27 Jul 2009 17:41:06 -0400
- To: Eric Prud'hommeaux <eric@w3.org>
- CC: SPARQL Working Group <public-rdf-dawg@w3.org>, "Seaborne, Andy" <andy.seaborne@hp.com>
Eric Prud'hommeaux wrote: > 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 That's the same as the MINUS-AntiJoin from my message (http://lists.w3.org/Archives/Public/public-rdf-dawg/2009JulSep/0030.html), right? I don't think that matched the intuition of most people that advocated MINUS on the teleconference, who preferred this definition with the added restriction that prevented removing solutions from the left-hand side that share no variables in common with any solutions from the right-hand side. (MINUS-AntiJoin+Restriction) Lee
Received on Monday, 27 July 2009 21:42:03 UTC