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[Frama-c-discuss] Problems with Nitrogen/Fluorine

Thank you for the response. I modified the program, i used the Jessie
plugin instead of the WP plugin and it works.
However "ACSL By Example" refers to Frama-C Nitrogen 20111001 used with the
WP plugin, as i tried originally.
Which can be the causes of this discrepancy between my version (in
attachment) and the one on the paper?

Kind regards,

    Alessio Iotti


2013/10/17 Guillaume Melquiond <guillaume.melquiond at inria.fr>

> On 17/10/2013 10:13, Alessio Iotti wrote:
>
>> Dear All, i am moving the first steps with Frama-C, following the
>> excellent tutorial "ACSL By Example".
>> I have encountered a problem trying to replicate the count algorithm
>> experiment. The attached file,
>> taken literally from "ACSL By Example", illustrates the problem in
>> comments beginning with "/***".
>>
>
> That is somehow fortunate that Fluorine fails at proving it, and that is
> kind of scary that Nitrogen (even partly) succeeded, because what you are
> trying to prove is plain wrong!
>
> Axiom count2 should have been written
>
> \forall int *a, v, integer i ;
>   (a[i] != v ==> Count(a, v, i, i+1) == 0) &&
>   (a[i] == v ==> Count(a, v, i, i+1) == 1);
>
> Once changed, all the proof obligations are verified.
>
> Best regards,
>
> Guillaume
>
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