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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>

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)

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Received on Monday, 27 July 2009 21:04:13 UTC

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