Termination Settings options

Network Optimization Settings

Gap Based Termination

The Relative and Absolute Gap settings are used to determine the limit to which the gap between the predicted optimal solution and the particular branch-and-bound solution can reach before a solution is returned, relative to the predicted optimal solution. For both, you can enter a single gap value (Relative Gap (%) and Absolute Gap). For additional control, you can use dynamic gap settings. These let you set two different gap values, based on the time that has elapsed in the solve. For example, you may want a relative gap of 0.1 percent once the solve has been running for one hour, then relax it to 1 percent if the solve is still running after two hours.

Relative Gap (%): For Network Optimization, this option determines the limit to which the gap between the predicted optimal solution and the particular branch-and-bound solution can reach before a solution is returned, relative to the predicted optimal solution. For example, to stop the global search when an MIP solution has been found that is within 5% of the optimal solution, set the relative gap to 5. This will be written to the params.dat file as 0.05. The default is 0.01% (0.0001). To set this value in a scenario, select “Relative Gap (%)” as the field from the Network Optimization Options table and enter the numeric value representing the gap value.

Enable Dynamic Gap % Termination: Select this setting if you want to be able to define one or two different gap percent values based on elapsed time in the solve.

Stage 1 Gap % Start Time (secs): Enter the amount of time that has elapsed in the solve when the Stage 1 Percent is applied as the relative gap value.

Stage 1 Gap %: Enter the relative gap percent value that should be used once the solve has run for the time specified by Stage 1 Start Time (secs). For example, you may want to start with a Relative Gap (%) of 0.01, but after one hour, increase that gap to 0.1.

Stage 2 Gap % Start Time (secs): Enter the amount of time that has elapsed in the solve when the Stage 2 Percent is applied as the relative gap value.

Stage 2 Gap %: Enter the relative gap percent value that should be used once the solve has run for the time specified by Stage 2 Start Time (secs). For example, you may want to start with a Relative Gap (%) of 0.01, but after two hours, increase that gap to 1.

Absolute Gap: For Network Optimization, this option determines the limit to which the gap between the predicted optimal solution and the particular branch-and-bound solution can reach before a solution is returned. For example, to stop the global search when an MIP solution has been found that is within 100 of the optimal solution, set the absolute gap to 100. The default is 0.0. To set this value in a scenario, select “Absolute Gap” as the field from the Network Optimization Options table and enter the numeric value representing the gap value.

Enable Dynamic Abs. Gap Term.: Select this setting if you want to be able to define one or two different absolute gap values based on elapsed time in the solve.

Stage 1 Absolute Gap Start Time (secs): Enter the amount of time that has elapsed in the solve when the Stage 1 Gap is applied as the absolute gap value.

Stage 1 Absolute Gap: Enter the absolute gap value that should be used once the solve has run for the time specified by Stage 1 Start Time (secs). For example, you may want to start with an Absolute Gap of 0, but after one hour, increase that gap to 1000000.

Stage 2 Absolute Gap Start Time (secs): Enter the amount of time that has elapsed in the solve when the Stage 2 Gap is applied as the absolute gap value.

Stage 2 Absolute Gap: Enter the absolute gap value that should be used once the solve has run for the time specified by Stage 2 Start Time (secs). For example, you may want to start with an Absolute Gap of 0, but after two hours, increase that gap to 2000000.

Time Based Termination

Time Limit (secs): This is the limit in seconds for the Network Optimization to run. At the end of the time limit, if more than one solution is found, the best solution calculated to that time will be returned. To set this value in a scenario, select “Time Limit (secs)” as the field from the Network Optimization Options table and enter the numeric value representing the number of seconds in the time limit. You can combine this with the continuation option described below by creating a second scenario item that sets the "Continue until at least one NO solution is found" field from the Network Optimization Options table to "Yes".

Time Limit Since Last Solution (secs): This is the limit in seconds for the Network Optimization to run since it last found a solution. At the end of the time limit, if a new solution has not been found, the solve ends and the best solution calculated to that time will be returned. To set this value in a scenario, select “Time Limit (secs)” as the field from the Network Optimization Options table and enter the numeric value representing the number of seconds in the time limit. Create a second scenario item that sets the Continue until at least one NO solution is found" field from the Network Optimization Options table to "Yes".

Time Limit Since Last Improvement (secs): This is the limit in seconds for the Network Optimization to run since the solution value was improved. At the end of the time limit, if a there has been no improvement and the gap has not been lessened, the solve ends and the best solution calculated to that time will be returned. *** To set this value in a scenario, select “Time Limit (secs)” as the field from the Network Optimization Options table and enter the numeric value representing the number of seconds in the time limit. Create a second scenario item that sets the "NO Continue Until Solution Found" field from the Network Optimization Options table to "Yes".

Continue until at least one NO solution is found: This option is only available if a numeric Time Limit is specified. If no solution is found within the Time Limit and this option is selected, the optimization will continue to run until an integer solution is found. This option also overrides the Time Limit Since Last Solution (secs) and Time Limit Since Last Improvement (secs) - the optimization continues after the time limit(s) have been reached. To set this value in a scenario, select “Time Limit (secs)” as the field from the Network Optimization Options table and enter a positive numeric value. When the “Time Limit (secs)” is a positive value, this option is enabled; when the “Time Limit (secs)” is a negative value, this option is disabled.

System Resource Based Termination

Memory Consumption Limit (%): This is the maximum amount of available memory that the solver can consume when it runs. If this threshold is exceeded, the solve ends and the best solution calculated to that point will be returned. ***To set this value in a scenario, select “Memory Consumption Limit (%)” as the field from the Network Optimization Options table and enter the numeric value representing the percentage of memory consumption threshold.