title: How can I ensure that the 2nd index of my binary decision variable is equal in every solution?
body: <p>I have a binary decision variable <code>x[l][c][f]</code>. <code>F</code> can range between 1-6. Now I want <code>f</code> to be equal in every solution. So whenever the binary variable is equal to 1, <code>f</code> must be the same (1-6) for all non zero binary variables. So in the solution, every <code>x</code> has the same index for <code>f</code>.</p>
  
  <pre><code>Range F = 1..6;
  
  Range L = 1..28;
  
  Range C = 1..6;
  
  dvar boolean x[L][C][F];  // bin decision variable equal to 1 if line l is jused with c carriages at a frequency of f
  
  Forall (l in L, c in C, f in F)
  (x[l][c][f]==1) =&gt; ??
  </code></pre>