/* Dining philosophers, standard version, which deadlocks.
 *
 *		civl verify -inputB=4 diningBad.cvl
 * or (if you want to find the minimal counterexample)
 *		civl verify -inputB=4 diningBad.cvl -min
 */
#include <civlc.cvh>

$input int B = 4; // upper bound on number of philosophers
$input int n;     // number of philosophers
$assume(2<=n && n<=B);

_Bool forks[n]; // Each fork will be on the table ($true) or in a hand ($false).

void dine(int id) {
  int left = id;
  int right = (id + 1) % n;

  while (1) {
    $when (forks[left]) forks[left] = $false;
    $when (forks[right]) forks[right] = $false;
    forks[right] = $true;
    forks[left] = $true;
  }
}

void main() { 
  $for(int i: 0 .. n-1)
    forks[i] = $true;
  $parfor(int i: 0 .. n-1)
    dine(i);
}