W3C home > Mailing lists > Public > public-rdf-dawg@w3.org > July to September 2009

RE: More on MINUS vs. UNSAID

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>
Message-ID: <20090727210330.GE4887@w3.org>
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

office: +1.617.258.5741 32-G528, MIT, Cambridge, MA 02144 USA
mobile: +1.617.599.3509

(eric@w3.org)
Feel free to forward this message to any list for any purpose other than
email address distribution.

There are subtle nuances encoded in font variation and clever layout
which can only be seen by printing this message on high-clay paper.
Received on Monday, 27 July 2009 21:04:13 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 16:15:39 GMT