title: GAMS- uncontrolled set entered as constant
body: <p>Consider the following problem in GAMS. I have two disjoint sets:
  <code>i</code>and <code>j</code>. These are proper subsets of a subset <code>k</code>, where the union of <code>i</code> and <code>j</code> exactly equal the elements of <code>k</code>. I wish to construct a new variable X(<code>k</code>) (for the proper subset), that is a concatenation of A(<code>i</code>) and B(<code>j</code>). Intuitively, I wish to declare:</p>
  <pre><code>parameter 
  X(k);
  
  X(k)=A(i)+B(j);
  </code></pre>
  <p>Of course, this operation is not legal as i and j do not conform. But the idea is to take the values from A(i) for the i elements of X(k), and the rest to be taken from B(j). Any help on this is much appreciated!!</p>