Solution

Optimality

A solution is optimal, if there is no other solution with a better rating.

\[ \begin{aligned} &optimal(X) = \begin{cases} \;\;wahr, & \text{if} X = (x_{11},...,x_{DS})\\ &best \ rating(X)\\ \;\;false, & \text{otherwise}. \end{cases} \end{aligned} \]