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[Frama-c-discuss] predicate problem in Carbon

  • Subject: [Frama-c-discuss] predicate problem in Carbon
  • From: marsishandsome at gmail.com (mars Gu)
  • Date: Fri, 18 Feb 2011 11:29:04 +0100
Hello,

i have a problem about the predicate in Carbon.
I run the following program with the command: frama-c-gui -wp -wp-rte
-wp-proof alt-ergo -wp-no-arrays example.c
The assertion in Line 27 can be proved, but the loop invariant in Line 19,
which is the same as the assertion in Line 27, cannot be proved.

Regards,
Liangliang Gu

typedef int size_type;
/*@
  predicate
    PreExample{L}(int* a, int i) =
\forall integer k;  0 <= k < i ==> a[k] == 1024;
*/
/*@
  requires n >= 0;
  requires \valid_range(a, 0, n-1);
  assigns a[0..n-1];
  ensures \forall integer i; 0 <= i < n ==> a[i] == 1024;
*/
void example(int* a, int n)
{
  size_type i = 0;
  /*@
    loop invariant 0 <= i <= n;
loop invariant \forall integer k; 0 <= k < i ==> a[k] == 1024;
 loop invariant PreExample(a, i);

loop assigns a[0..i-1], i;
    loop   variant n-i;
  */
  while (i < n) {
    a[i] = 1024;
    i++;
    //@ assert PreExample{Here}(a, i);
  }
}
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