Infeasibility Analysis

This section explains how the page Infeasibility Analysis works in the application. This page becomes visible only if you clicked on the Optimize button but the model can not be solved. In this case, the page Infeasibility Analysis helps you understand why the model is infeasible.

Example

Imagine the situation when the entered demand for a product is higher then the supply for that product in the input dataset. This means that the demand for a particular product summed over all customers exceeds the supply for that product summed over all suppliers. In this case, there is no feasible solution which meets all the required demands and yet, does not exceed the maximum available supply for each of the suppliers.

When the solver detects such an infeasibility problem, a warning message is displayed. In this case, you can choose to go to the Infeasibility Analysis page for help in finding the causes of infeasibility.

At this stage the Infeasibility Analysis step becomes visible in the Workflow menu:

When you navigate to the Infeasibility Analysis page you can find a table which shows the violated constraint(s):

In the example at hand the customer demand is violated, but at that point it is not yet determined which customer and product are problematic. In order to determine these, the model can be re-run from this screen in a “relaxed” mode by clicking on the icon on the left corner of the page. In this mode, some of the constraints are temporarily relaxed to allow the optimizer to determine which ones are infeasible (or contradictory) in the original model.

After re-running the relaxed model, some additional tables become visible and show the problematic elements, depending on the reason of infeasibility. In this example, the Demand Violation table becomes visible and shows the customer, location, product, and period which caused the infeasibility.

If you click on an element in the violation column in the Demand Violation table, the Explanation of unmet demand table will show why the customer demand cannot be fulfilled.