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(* Title: HOL/UNITY/UNITY


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ID: $Id$


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Author: Lawrence C Paulson, Cambridge University Computer Laboratory


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Copyright 1998 University of Cambridge


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The basic UNITY theory (revised version, based upon the "co" operator)


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From Misra, "A Logic for Concurrent Programming", 1994


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*)


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UNITY = LessThan +


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constdefs


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constrains :: "[('a * 'a)set set, 'a set, 'a set] => bool"


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"constrains Acts A B == ALL act:Acts. act^^A <= B"


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stable :: "('a * 'a)set set => 'a set => bool"


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"stable Acts A == constrains Acts A A"


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strongest_rhs :: "[('a * 'a)set set, 'a set] => 'a set"


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"strongest_rhs Acts A == Inter {B. constrains Acts A B}"


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unless :: "[('a * 'a)set set, 'a set, 'a set] => bool"

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"unless Acts A B == constrains Acts (AB) (A Un B)"

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end
