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.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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

Naghmeh Ghafari wrote:
> Hi,
>
> I am trying to verify a very simple bubble sort example, using jessie 
> (Beryllium). My default solver is Alt-Ergo.  I used HAVOC (and Z3) to 
> verify this example, which was relatively straight forward. I am using 
> similar loop invariants, but  still there is a safety property 
> 'variant decrease' that I can't verify. I think this is because of the 
> While(true) loop I have for which I cannot come up with a proper 
> strictly decreasing loop variant. I also cannot verify my post 
> condition. I appreciate any suggestions or hint. 
Hi,

I'm very surprised that you could prove your post-condition with HAVOC. 
For me you need a smart loop invariant for the inner loop to prove it. 
Could you double-check the annotations you gave to havoc, and perhaps 
share the annotated file with us ?

Regarding the termination of the loop: my guess is that by default, 
havoc does not check termination.

- Claude

> In my version of jessie, I cannot  use  #pragma 
> JessieTerminationPolicy (user). It is not recognized in my version.
>
> cheers,
> naghmeh
>
> #define TRUE 1
> #define FALSE 0
>
>
> /*@ requires size > 0;
>   @  requires \valid(arr+ (0..size-1));
>   @  ensures \forall int i; 0 <= i <= size - 2 ==> arr[i] <= arr[i+1];
> */
>
> void bubble_sort(int *arr, int size) {
>
>   while (TRUE) {
>     int aux = 0;
>     int i = 0;
>
>     /*@ loop invariant 0 <= i && i <= size -1 ;
>       @          loop variant size - i;
>       @*/
>     while (i < size-1) {
>       if (arr[i] > arr[i+1]) {
>           int tmp = arr[i];
>           arr[i] = arr[i+1];
>           arr[i+1] = tmp;
>           aux = i;
>       }
>       i++;
>    }
>    if (aux == 0) break;
>   }
> }
>
>
>
>
>
>
> _______________________________________________
> Frama-c-discuss mailing list
> Frama-c-discuss at lists.gforge.inria.fr
> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/frama-c-discuss


-- 
Claude March?                          | tel: +33 1 72 92 59 69           
INRIA Saclay - ?le-de-France           | mobile: +33 6 33 14 57 93 
Parc Orsay Universit?                  | fax: +33 1 74 85 42 29   
4, rue Jacques Monod - B?timent N      | http://www.lri.fr/~marche/
F-91893 ORSAY Cedex                    |