| Name | stp3d |
| Download | stp3d.mps.gz |
| Solution | stp3d.sol.gz |
| Set Membership | Challenge Reoptimize |
| Problem Status | Hard |
| Problem Feasibility | Feasible |
| Originator/Contributor | T. Koch |
| Rows | 159488 |
| Cols | 204880 |
| Num. non-zeros in A | 662128 |
| Num. non-zeros in c | 75648 |
| Rows/Cols | 0.778445919563 |
| Integers | |
| Binaries | 204880 |
| Continuous | |
| min nonzero |Aij| | 1 |
| max |Aij| | 1 |
| min nonzero |cj| | 1.00001 |
| max |cj| | 1.00303 |
| Integer Objective | 493.71965 |
| LP Objective | 481.877786 |
| Aggregation | |
| Variable Bound | 129232 |
| Set partitioning | 82 |
| Set packing | 2171 |
| Set covering | |
| Cardinality | 28003 |
| Equality Knapsacks | |
| Bin packing | |
| Invariant Knapsack | |
| Knapsacks | |
| Integer Knapsack | |
| Mixed 0/1 | |
| General Cons. | |
| References | Koch2004 |
Steiner tree packing instance in a 3 dimensional grid-graph, LP relaxation is highly degenerate. Alkis Vazacopoulos reports finding the first feasible solution of this instance using XPRESS 2006B. This instance was solved by a first implementation of ParaSCIP using up to 2048 cores of HLRN-II(http://www.hlrn.de). ParaSCIP, mainly developed by Yuji Shinano, is an extension of SCIP and realizes a parallelization on a distributed memory computing environment. For being able to interrupt and warmstart the computations, ParaSCIP has a checkpoint mechanism. Therefore, selected subproblems are stored as warm start information, which allows to virtually run ParaSCIP, although the HLRN-II environment imposes a time limit of 48 hours per run. The problem was presolved several times with SCIP presolving techniques. After that, it took approximately 114 hours to solve this instance.