# Simheuristics Approaches for Efficient Decision-Making Support in Materials Trading Networks
## 7 Addressing the Performance Challenge: Reducing the Number of Evaluations  
Another performance measure of the LAS is the number of simulation runs, which we define to be the number of objective function evaluations. In order to reduce the number of evaluations of the objective function, a selective evaluation might be performed, or evaluations might be skipped. In this research, the evaluation of the impact of an action plan is skipped if the action plan has previously been evaluated [81]. Previously evaluated action plans might be identical to newly formed action plans, or they can be equivalent to them. Equivalent action plans have an identical impact on the performance of the distribution network, but are not identical action plans. Figure 8 shows an example of equivalent action plans. These action plans cause the same changes in the network and, hence, result in the same impact on the performance. The performance of an equivalent action plan can directly be used, without again evaluating the performance of the newly formed plan. \begin{table}
\begin{tabular}{c c c c c c c} \hline  & \(\mathbf{a_{1}}\) & \(\mathbf{a_{2}}\) & \(\mathbf{a_{3}}\) & \(\mathbf{a_{4}}\) & \(\mathbf{a_{5}}\) & \(\mathbf{a_{6}}\) & \(\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{ }}}}}}}}}}}}}}\) \\ \hline \(a_{1}\) & \(\sim\) & \(-\) & \(+\) & \(\sim\) & \(-\) & \(-\) \\ \(a_{2}\) & \(+\) & \(-\) & \(\sim\) & \(-\) & \(\sim\) & \(\sim\) \\... & & & & & & \\ \hline \end{tabular}
\end{table} 
Table 2: Correlation matrix example. Figure 7: Impact of sequence of actions on the service level. In order to identify equivalent action plans we define interchangeable and redundant actions. Interchangeable actions can be reordered in an action plan without affecting the impact of the action plan on the performance of the network (Figure 8a). Actions \(a_{1}\) and \(a_{2}\) in Figure 8a have been reordered without affecting the applied changes and the impact of the action plan on the service level; \(a_{1}\) and \(a_{2}\) are interchangeable actions. Actions that affect different entities in the network can be reordered without affecting the impact of the action plan. These actions are interchangeable if they do not interfere with an overall parameter of the network, such as the capacity of a site. For example, \(a_{1}\) increases the stock level of SKU 1 at site A, and \(a_{2}\) increases the stock level of SKU 2 at site A. Both actions affect different entities in the network, SKU 1 at site A and SKU 2 at site A. Applying the changes by any of the actions does not affect the changes applied by the other action. However, if the total capacity of site A reaches its limit after applying any of these actions, the resulting applied changes differ when the actions are swapped. Redundant actions can be removed from the action plan without affecting the impact of the action plan on the distribution network (Figure 8b). Action \(a_{5}\) has been removed from the action plan in Figure 8b. The resulting action plan applies the same changes as the original action plan, without removing \(a_{5}\), and the service remains unchanged. Action \(a_{5}\) is a redundant action, because its removal has no effect on the changes applied in the network. These actions can be duplicated structural actions. A structural action adds or removes entities from the network, and its duplication repeats these changes without causing additional changes in the network. A duplicated parametrical action that causes incremental changes is not redundant, because it causes an incremental increase or decrease in the value of the affected parameter. Defining the equivalent action plans based on interchangeable and redundant actions enables skipping the evaluation of an action plan. An action plan is rated as its equivalent action plan that was evaluated previously. Another approach reduces the number of actions to reduce the number of evaluations. In this approach, actions are grouped.