computeIIS ( void )
Compute an Irreducible Inconsistent Subsystem (IIS). An IIS is a subset of the constraints and variable bounds with the following properties:
- It is still infeasible, and
- If a single constraint or bound is removed, the subsystem becomes feasible.
IIS results are returned in a number of attributes: IISConstr, IISLB, IISUB, IISSOS, IISQConstr, and IISGenConstr. Each indicates whether the corresponding model element is a member of the computed IIS.
The IIS log provides information about the progress of the algorithm, including a guess at the eventual IIS size.
If an IIS computation is interrupted before completion, Gurobi will return the smallest infeasible subsystem found to that point.
This method populates the
SOS attribute, and the
You can also
obtain information about the results of the IIS computation by writing
.ilp format file (see
Model.write). This file
contains only the IIS from the original model.
Use the IISMethod parameter to adjust the behavior of the IIS algorithm.
Note that this method can be used to compute IISs for both continuous and MIP models.