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[Frama-c-discuss] Preservation of base loop invariant not verified

In fact, this does not seem to be the reason. It is not proved just 
because the trivial loop invariant below is missing

loop invariant j >= 1;

with this additional info, the preservation of the loop invariant

loop invariant j == 1 ==> i == \at(i, LoopEntry) + loop(0);

is a triviality, since j == 1 is false after any iteration of the loop.

Anyway, I don't see why your loop invariant is splitted into two parts: 
this should work :

     /*@ loop invariant j >= 1;
         loop invariant i == \at(i, LoopEntry) + loop(j - 1);
         loop invariant j >= 8 ==> is_hello_printed == 1;
         loop assigns i, j, is_hello_printed;
         loop variant 10 - j ;
         */

Hope this helps,

- Claude


Le 26/01/2015 10:05, Lo?c Correnson a ?crit :
> Your property P is not provable *by induction* ; it means that P(j+1) is not a logic consequence of P(j).
> (read in the WP manual about the proof obligations generated for loop invariants).
> Actually, there is nothing in your loop invariants about the value of (i) at any loop turn?
> L.
>
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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/
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