| # Nomenclature of a toy 2D optimization problem Consider the toy optimization problem in two variables: For this problem: The optimal value is . The optimal set is the singleton , with Since the optimal set is not empty, the problem is attained.
| An -sub-optimal set for the toy problem above is shown (in darker color), for . This corresponds to the set of feasible points that achieves an objective value less or equal than .
See also: Geometric view of the toy problem.