how much does solution pool completion proceeds
Answered
Dear Gurobi Community members,
I am using the pool solution to find all feasible solutions of my milp model (setting the PoolSolutions parameter to its max). But, when Gurobi starts to complete the solution pool, I cannot find out how much does it proceed.
How can I understand that how much does solution pool completion proceeds?
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Hi Akram,
To find more feasible solutions, in addition to setting the PoolSolutions parameter, you should also set the PoolSearchMode parameter to one of the non-default values.
You can find more information on this topic in the Finding Multiple Solutions documentation section.
Best regards,
Elisabeth
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Dear Elisabeth,
Thanks for your reply. I have read those parts and set the corresponding parameters. It seems that is working correct. However, I cannot find that how much has it proceeded (by the Gurobi log)!
Regards,
Akram
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Hi Akram,
The documentation page Solution Pool and Multi-Scenario Logging explains what you should see in the Gurobi log in the second phase (once attention has shifted towards finding solutions beyond that one optimal solution).
If this doesn't answer your question, could you share the logfile that you are analyzing?
Best regards,
Elisabeth
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Hi Elisabeth,
I heve set the parameters as follows:
PoolSolutions=2000000000 (max possible value)
PoolSearchMode=2
and here is some part of the gurobi log (if it helps):
Root relaxation: objective 3.000000e+00, 1 iterations, 0.00 seconds
Nodes | Current Node | Objective Bounds | Work
Expl Unexpl | Obj Depth IntInf | Incumbent BestBd Gap | It/Node Time* 0 0 0 3.0000000 3.00000 0.00% - 0s
Optimal solution found at node 0 - now completing solution pool...
Nodes | Current Node | Pool Obj. Bounds | Work
| | Worst |
Expl Unexpl | Obj Depth IntInf | Incumbent BestBd Gap | It/Node Time0 0 - 0 - 3.00000 - - 0s
0 0 - 0 - 3.00000 - - 0s
0 2 - 0 - 3.00000 - - 0s
72883 5972 cutoff 138 - 3.00000 - 0.0 7s
88899 6362 - 135 - 3.00000 - 0.0 10s
120931 6886 cutoff 138 - 3.00000 - 0.0 19s
136947 7186 - 137 - 3.00000 - 0.0 26s
152963 7400 - 137 - 3.00000 - 0.0 33s
168979 7656 cutoff 138 - 3.00000 - 0.0 41s
184995 7956 cutoff 138 - 3.00000 - 0.0 52s
201011 8202 cutoff 138 - 3.00000 - 0.0 63s
217027 8380 - 134 - 3.00000 - 0.0 76s
233043 8886 - 137 - 3.00000 - 0.0 90s
249059 9038 cutoff 138 - 3.00000 - 0.0 106s
265075 9290 - 137 - 3.00000 - 0.0 123s
281091 9454 - 136 - 3.00000 - 0.0 141s
297107 9622 cutoff 138 - 3.00000 - 0.0 160s
313123 9760 - 135 - 3.00000 - 0.0 181s
329139 9936 - 131 - 3.00000 - 0.0 203s
345155 10170 - 136 - 3.00000 - 0.0 227s
361171 10288 - 137 - 3.00000 - 0.0 252s
377187 10356 cutoff 138 - 3.00000 - 0.0 279s
393203 10472 cutoff 138 - 3.00000 - 0.0 308s
409219 10626 cutoff 138 - 3.00000 - 0.0 338s
425235 10718 cutoff 138 - 3.00000 - 0.0 370s
441251 10796 - 136 - 3.00000 - 0.0 403s
457267 10868 cutoff 138 - 3.00000 - 0.0 437s
473283 10940 cutoff 138 - 3.00000 - 0.0 474s
489299 11024 cutoff 138 - 3.00000 - 0.0 510s
505315 11082 cutoff 138 - 3.00000 - 0.0 548s
521331 11116 cutoff 138 - 3.00000 - 0.0 587s
537347 11118 cutoff 138 - 3.00000 - 0.0 627s
553363 11138 cutoff 138 - 3.00000 - 0.0 669s
569379 11176 cutoff 138 - 3.00000 - 0.0 712s
585395 11236 cutoff 138 - 3.00000 - 0.0 757s
601411 11312 - 137 - 3.00000 - 0.0 803s
617427 11302 - 137 - 3.00000 - 0.0 852s
633443 11336 cutoff 138 - 3.00000 - 0.0 902s
649459 11354 - 136 - 3.00000 - 0.0 955s
665475 11354 - 137 - 3.00000 - 0.0 1009s
681491 11376 cutoff 138 - 3.00000 - 0.0 1064s
697507 11402 cutoff 138 - 3.00000 - 0.0 1122s
713523 11436 - 137 - 3.00000 - 0.0 1180s
729539 11480 cutoff 138 - 3.00000 - 0.0 1239s
745555 11448 - 137 - 3.00000 - 0.0 1299s
761571 11446 - 137 - 3.00000 - 0.0 1361s
777587 11412 - 137 - 3.00000 - 0.0 1424s
793603 11338 - 136 - 3.00000 - 0.0 1490s
809619 11324 - 133 - 3.00000 - 0.0 1562s
825635 11294 cutoff 138 - 3.00000 - 0.0 1634s
841651 11294 cutoff 138 - 3.00000 - 0.0 1708s
857667 11264 - 136 - 3.00000 - 0.0 1783s
873683 11292 cutoff 138 - 3.00000 - 0.0 1860s
889699 11282 cutoff 138 - 3.00000 - 0.0 1937s
905715 11278 - 137 - 3.00000 - 0.0 2017s
921731 11260 cutoff 138 - 3.00000 - 0.0 2098s
937747 11274 cutoff 138 - 3.00000 - 0.0 2180s
953763 11238 - 135 - 3.00000 - 0.0 2263s
969779 11252 - 136 - 3.00000 - 0.0 2347s
985795 11294 cutoff 138 - 3.00000 - 0.0 2433s
1001811 11294 - 130 - 3.00000 - 0.0 2521s
1017827 11284 - 137 - 3.00000 - 0.0 2610s
1033843 11250 cutoff 138 - 3.00000 - 0.0 2700s
1049859 11226 - 137 - 3.00000 - 0.0 2790s
1065875 11244 cutoff 138 - 3.00000 - 0.0 2882s
1081891 11200 - 132 - 3.00000 - 0.0 2975s
1097907 11188 cutoff 138 - 3.00000 - 0.0 3070s
1113923 11130 cutoff 138 - 3.00000 - 0.0 3166s
1129939 11128 - 137 - 3.00000 - 0.0 3264s
1145955 11104 cutoff 138 - 3.00000 - 0.0 3363s
1161971 11082 cutoff 138 - 3.00000 - 0.0 3464s
1177987 11098 - 137 - 3.00000 - 0.0 3566s
1194003 11076 - 134 - 3.00000 - 0.0 3673s
1210019 11060 cutoff 138 - 3.00000 - 0.0 3782s
1226035 11052 cutoff 138 - 3.00000 - 0.0 3892s
1242051 11078 - 134 - 3.00000 - 0.0 4001s
1258067 11052 cutoff 138 - 3.00000 - 0.0 4112s
1274083 11006 - 136 - 3.00000 - 0.0 4230s
1290099 11064 - 137 - 3.00000 - 0.0 4350s
1306115 11108 - 137 - 3.00000 - 0.0 4471s
1322131 11122 cutoff 138 - 3.00000 - 0.0 4591s
1338147 11176 - 137 - 3.00000 - 0.0 4713s
1354163 11174 - 136 - 3.00000 - 0.0 4835s
1370179 11262 cutoff 138 - 3.00000 - 0.0 4956s
1386195 11254 cutoff 138 - 3.00000 - 0.0 5079s
1402211 11218 - 134 - 3.00000 - 0.0 5204s
1418227 11256 cutoff 138 - 3.00000 - 0.0 5330s.
.
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Do you know how can I understand how is the solution pool completion proceeding?
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Seeing the progress is not so easy when completing the solution pool. Obviously, the gap doesn't give you any indication anymore. The only relevant statistics that you can look at are the number of open nodes. In your case, this grew up to about 11400 nodes and seems to stay in this range. So, there is not yet any sign of getting done.
You could install a callback and query the MIP_SOLCNT value to know how many solutions are already in the pool. But if you don't know how many solutions exist for your model, this value won't be very useful either in assessing the progress.
Regards,
Tobias
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Dear Tobias,
Thanks for your reply. That was a great guide for me!
Best regards,
Akram
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