# Frama-C-discuss mailing list archives

This page gathers the archives of the old Frama-C-discuss archives, that was hosted by Inria's gforge before its demise at the end of 2020. To search for mails newer than September 2020, please visit the page of the new mailing list on Renater.

# [Frama-c-discuss] question about a simple example and jessie

```Naghmeh Ghafari wrote:
> I was trying to verifying the same code using Frama-C. Even if I
> translate the second loop_assert for the inner loop as following:
>
>  @    loop invariant \forall int a,b; ((aux < a <= i+1) && (aux < b <=
> i+1) ==> (a <= b ==> arr[a] <= arr[b]));
>

Indeed, I cannot confirm that this is equivalent to the HAVOC invariant
_be_cause __it_is very _hard to __read __havoc_syntax :-)

You could simplify your formula into

@    loop invariant \forall integer a,b; aux < a <= b <= i+1 ==> arr[a]
<= arr[b];

and I believe it is almost  the correct invariant  to use for proving
your bubble sort.  I suggest now to forgot about
HAVOC invariant and start thinking to see if it is really the proper
invariant: is it aux < a or aux <= a ? is it i+1 or i ?
Take a paper and write that down, you should find to correct formula.

- Claude

> (which I am not sure if it is completely equivalent to the HAVOC
> notation), I still cannot use Frama-C to verify this code. Then I
> tried the implementation that was suggested by Pascal (on this mailing
> list) and I  cannot verify even th eother implementation using
> Frama-C.  I am relatively new to both tools. I have worked with Boogie
> and Z3 before, but not with HAVOC front end, so now exploring both
> HAVOC and jessie plugin at the same time. That's why I am trying to
> use the same implementation. I really appreciate any help and
> suggestions.
>

```