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(* Title: HOL/UNITY/Channel
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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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Unordered Channel
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From Misra, "A Logic for Concurrent Programming" (1994), section 13.3
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*)
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Channel = WFair + Option +
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types state = nat set
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consts
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F :: state program
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constdefs
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minSet :: nat set => nat option
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"minSet A == if A={} then None else Some (LEAST x. x:A)"
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rules
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UC1 "F : constrains (minSet -`` {Some x}) (minSet -`` (Some``atLeast x))"
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(* UC1 "F : constrains {s. minSet s = x} {s. x <= minSet s}" *)
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UC2 "F : leadsTo (minSet -`` {Some x}) {s. x ~: s}"
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end
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