CristalCaveGem » LustreC » Lustrec-Tests

--

-- 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 5:

-- ((p -k-> q and ([[q]] => length <= m))  => ([[p]] => length <= k+m)

-- Not provable in luke-*

node top (k0, m0: int; p, q : bool) returns (OK: bool);

--@ contract guarantees OK;

var k,m: int;

    env : bool;

let

    k = k0-> pre(k);

    m = m0-> pre(m);

    env = Sofar( (k>=1 and m>=1) and (Age(p)>=k => q) and (Age(q)<= m) );

    OK = env => (Age(p) <= k+m);

    --%PROPERTY OK=true;

    --%MAIN;

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