Figure 4.63: The Presolve Tab in the GUROBI Options Dialog Box
You can change the Presolve options for GUROBI by choosing GUROBI parameters from the Options menu and then pressing the Presolve tab. This will display the dialog box shown below:
Figure 4.63: The Presolve Tab in the GUROBI Options Dialog Box
| Option Name | MPL Name | Solver Param | ParamNr | Type | Default | Min | Max |
|---|---|---|---|---|---|---|---|
| Presolve | PresolveLevel | PRESOLVE | 9 | list | -1 | -1 | 2 |
| Presolve Pass Limit | PresolvePasses | PRESPASSES | 67 | int | -1 | -1 | maxint |
| Presolve Crush | PresolveCrush | PRECRUSH | 17 | flag | 0 | 0 | 1 |
| Use Aggregation | AggregateFlag | AGGREGATE | 14 | flag | 1 | 0 | 1 |
| Fill Value | MipAggrFill | AGGFILL | 53 | int | 10 | 0 | maxint |
| Dependent Row Reduction | PresolveDepRow | PREDEPROW | 66 | list | -1 | -1 | 2 |
| Forming Dual | PreDual | PREDUAL | 65 | list | -1 | -1 | 2 |
| Sparsify Reduction | PreSparsify | PRESPARSIFY | 17 | flag | 0 | 0 | 1 |
| Dual Reduction | DualReductions | DUALREDUCTIONS | 30 | flag | 1 | 0 | 1 |
| Quadratic Linearization | PreMIQPLinearise | PREQLINEARIZE | 31 | list | -1 | -1 | 1 |
| MIQP Method | PreMIQPMethod | PREMIQPMETHOD | 58 | list | -1 | -1 | 1 |
Controls the presolve level.
| Automatic (-1) | GUROBI decides. |
| None (0) | No presolve. |
| Conservative (1) | Conservative level of presolve. |
| Aggressive (2) | Aggressive level of presolve. |
Limits the number of passes performed by presolve. The default setting (-1) chooses the number of passes automatically.
Enables or disables the translations of the constraints on the original model to the equivalent constraints in the presolved model.
Enables or disables aggregation in presolve.
Controls the amount of fill allowed during presolve aggregation. Larger values generally lead to presolved models with fewer rows and columns, but with more nonzeros.
Controls the presolve dependent row reduction, which eliminates linearly dependent constraints from the constraint matrix.
| Conitnous Models (-1) | Applies to LPs not MIPs models. |
| Turn Off (0) | No Reduction. |
| All Models (1) | Reduction for all model types. |
Controls whether presolve forms the dual fo a continuous model. Depending on the structure of the model, solving th edual can reduce solution time.
| Hueristic (-1) | Uses Heuristic to decide. |
| Primal (0) | No Dual formed. |
| Dual (1) | Uses Dual. |
| Both (2) | Uses expensive hueristic to form both dual and primal models. |
Enables the presolve sparsify reduction for MIP models. This reduction can somethimes significantly reduce the number of nonzer values in the presolved model.
Determines whether dual reductions are performed.
Controls presolve Q matrix linearization for Quadratic models.
| Automatic (-1) | Automatically determined. |
| Do not transform (0) | No transformation attempted. |
| Transform into MILP (1) | Attempts to linearize MIQP/MIQCP to MILP. |
Controls the transformation presolve performs on MIQP models.
| Automatic (-1) | Uses Heuristic to decide. |
| Do not transform (0) | Leaves model as MIQP. |
| Transform into MILP (1) | Transforms MIQP to MILP. |