CristalCaveGem » LustreC

--

-- Source: Bertrand Jeannet

--

node Sofar( X : bool ) returns ( Sofar : bool );

let

    Sofar = X -> X and pre Sofar;

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node Age (p: bool) returns (age_of_p: int);

-- how long has p been maintained true in the strict past

let

 age_of_p = 0 -> if pre(p) then pre(age_of_p) + 1 else 0;

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-- Theorem 3:

-- (p -k-> q and r -k-> t) => (p and r) -k-> (q and t)

-- Not provable in luke-*

node top (k0: int; p, q, r, t : bool) returns (OK: bool);

var k: int;

    env : bool;

let

    k = k0-> pre(k);

    env = Sofar((k>=1) and (Age(p)>=k => q)  and (Age(r)>=k => t));

    OK = env => ((Age(p and r)>=k) => (q and t));

    --%PROPERTY OK=true;

    --%MAIN;

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