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# [Frama-c-discuss] Average Problem

• Subject: [Frama-c-discuss] Average Problem
• From: Claude.Marche at inria.fr (Claude Marché)
• Date: Fri, 03 Oct 2014 08:52:14 +0200
• References: <54291115.1080500@gmail.com> <542911A4.5010109@gmail.com> <043C3AA7-9E35-4C73-9AB2-07B8D812B84F@cea.fr> <542D7CC1.1060606@gmail.com>

Hello,

Your axiomatization of Sum is probably inadequate. It should be clear in
your mind if Sum(a,i,j) includes also a[j] or not. Your axioms do not
seem to be coherent with that respect.

I attach a very similar example coming from the test suite of Jessie
(available in subdir tests/c of Why distribution).

The two lemmas sum3 and sum_footprint need some induction reasoning to
be proved, so in the current state of technology in Frama-C + either
Jessie or WP plugins, an interactive prover like Coq is needed to prove
them. But you can safely admit them for the rest of the code.

Hope this helps,

- Claude

Le 02/10/2014 18:26, Sebastian a ?crit :
> Hi,
> I followed your instructions and I tried to implement the axiomatic Sum.
> I am using "Frama-C Neon-20140301" with Alt-Ergo prover on Ubuntu 14.04.
> I have tried to test it with a simple example but my axiomatic Sum
> doesn't work and I am not able to find the error.
> I have made a "functionTest" function that calls "testSum" function with
> array elements that satisfy the requirements of "testSum" requires
> clause, but the prover was not able to prove it.
> I attached the axiomatic Sum definition, the "testSum" function and the
> "functionTest" function.
> Could you please suggest how I can proceed with finding a solution to
> this problem?
>
> Thank you very much.
> Best regards,
> Sebastian
>
>
>
> Il 29/09/14 14:12, Lo?c Correnson ha scritto:
>> Hi,
>> \sum and \lambda are unsupported with WP.
>> Instead, you can axiomatize your sum or use an inductive predicate.
>>
>> See
>> ? 3.8.1 is a good hint.
>>     L.
>>
>>
>>
>> Le 29 sept. 2014 ? 10:00, Sebastian <sdavrieux at gmail.com> a ?crit :
>>
>>> Good morning,
>>>     I'm trying to do the average without overflow, however I'm not
>>> able to check an assert that contains \sum annotation.
>>> So I decided to make a simpler function that only uses \sum, but it
>>> doesn't work. What can I do to solve the problem?
>>>
>>> Best regards,
>>> Sebastian
>>> <testSum.c>_______________________________________________
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>>> Frama-c-discuss at lists.gforge.inria.fr
>>> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/frama-c-discuss
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>
>
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--
Claude March?                          | tel: +33 1 72 92 59 69
INRIA Saclay - ?le-de-France           |
Universit? Paris-sud, Bat. 650         | http://www.lri.fr/~marche/
F-91405 ORSAY Cedex                    |

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