$title Example: Use of subsets in equation definitions $onuellist set I / A, B, 1*20 /; * J declared to be a subset of I that doesn't contain its first two * elements set J(I) / 1*20 /; variable x(I), dummy_cost; equation fibonacci(J) objective; x.fx("A") = 1; x.fx("B") = 1; fibonacci(J(I)).. x(I) =e= x(I-1) + x(I-2); objective.. dummy_cost =e= 0; model fib /all/; solve fib using lp minimizing dummy_cost; display x.l;