The semantics of LeftJoin read Definition: LeftJoin Let Ω1 and Ω2 be multisets of solution mappings and F a filter. We define: LeftJoin(Ω1, Ω2, expr) = Filter(expr, Join(Ω1, Ω2)) set-union Diff (Ω1, Ω2, expr) card[LeftJoin(Ω1, Ω2, expr)](μ) = card[Filter(expr, Join(Ω1, Ω2))] (μ) + card[Diff(Ω1, Ω2, expr)](μ) Presumably, this should read Definition: LeftJoin Let Ω1 and Ω2 be multisets of solution mappings and expr a filter. We define: LeftJoin(Ω1, Ω2, expr) = Filter(expr, Join(Ω1, Ω2)) set-union Diff (Ω1, Ω2, expr) card[LeftJoin(Ω1, Ω2, expr)](μ) = card[Filter(expr, Join(Ω1, Ω2))] (μ) + card[Diff(Ω1, Ω2, expr)](μ) Frank McCabeReceived on Sunday, 28 October 2007 18:57:13 GMT
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