Analyzing the Explanation Log

The explanation log of a DS optimization run is a powerful tool to facilitate understanding of the solution calculated by the DS Optimizer. It can be used in the testing phase of an implementation project to compare different optimization results based on different settings for the objective weights in the fitness function of the optimization algorithm or due to other options selected in the Optimization Profile. However, it can also be used during productive use of the optimizer to identify the root cause of order delays in a specific planning situation.

To evaluate the results of an optimization run, you can use the explanation log. In addition to the optimization log that contains the technical data for the optimization run, you can also use an explanation log. In the explanation log, you can display explanations about the optimization results to better understand and evaluate these results. You must have set the Explain Result indicator on the Expert Settings tab page in the Optimization Profile for the system to create an explanation log after the optimization run. To display the rescheduled activities and the solutions found in the explanation log, you must also set the Log Result and Log Interim Solution.

There are two options on how you can access the explanation log. Either, you can open the explanation log from the list of optimization runs, in transaction /SAPAPO/OPT11, by placing the cursor on the row of the optimization run in question and choosing the Explanation Log button. Otherwise, if you have started the optimization run from the detailed scheduling planning board, the system creates a log for the optimization run. Choosing the Details icon in the log takes you also to the explanation log.

The following information is displayed in the explanation log:

• Delays - On this tab page, you can view the orders that are delayed. The delay tab consists of two tables. The upper table displays the delayed order and its delay. Double-clicking on any order opens a second table underneath, where you can see the reasons for the delay. The explanation log displays all the relevant orders in the lower section of the screen. For each order, the system displays the reason for and the duration of the delay. In addition, depending on the cause, the system displays the missing component quantity or the resource that caused the delay.
• Fixings - On this tab page, you can view the fixed activities. The fixing reasons are also specified.
• Delay: Resources - This tab page is divided into two tables. The first table lists all resources that have caused a delay in the optimization run. It also summarizes how many orders have been delayed because of this resource and the total amount of the delay. Double-clicking on any resource opens a second table listing all orders that have been delayed because of this resource. Essentially, this is the same information as shown on the Delay tab, but viewed from a different perspective (not from the order, but from the resource).
• Delay: Products - This tab page is also divided into two tables. The first table lists all products (components) that have caused a delay in the optimization run. It also summarizes how many orders have been delayed because of this product and the total amount of the delay. Double-clicking on any product opens a second table listing all orders that have been delayed because of this product. Essentially, this is the same information as shown on the Delay tab, but viewed from a different perspective (not from the order, but from the product/component).
• Deallocations - On this tab page, you can view the activities that were deallocated in the optimization run. The causes that led to the activity deallocation are also specified.
• Reschedulings - On this tab page, you can view the activities that were rescheduled in the optimization run.
• Solutions - On this tab page, you can view information about the quality of the solution found, such as the duration, the makespan, and the total setup times.