Infeasibility Analysis in the Xpress Optimizer

iis command). An IIS is a statement of a particular conflict in the model between a set of constraints and bounds, which make the problem certainly infeasible. An IIS is minimal in the sense that if any constraint or bound of the IIS were removed from the subproblem represented by the IIS, the resulting (relaxed) subproblem would be feasible. The Xpress Optimizer also contains a tool to identify the minimum weighted violations of constraints or bounds that would make the problem feasible (called repairinfeas). Both iis and repairinfeas can be applied to any LP, convex QP, or convex QCQP problem, as well as to their mixed integer counterparts. Please refer to the Xpress Optimizer and Mosel reference manuals for more information.