Skip to main content

Large MIP Model Stops Progressing - Many Equivalent Solutions?

Answered
RALPH ASHER
  • Edited
Gurobi-versary
First Comment
First Question

I have a MIP model for a manufacturing plant production optimization.  The objective function is to maximize production (in pounds of product) out of the plant, limited by a demand input per modeled SKU (the plant does not have enough capacity to produce all demand for all modeled SKUs)

 Due to some unique operational constraints in the plant, the model is very heavy on binary decision variables.  My MIP makes reasonable progress for several hours then makes almost no progress (<1% improvement) at all.  I suspect this may be because since the objective function is just to maximize pounds out of the plant, there are potentially a lot of different manufacturing sequences that enable that same volume, and Gurobi is getting hung up on that.

Any help is appreciated, log is below.  I stopped the model after 36 hours, when it was making no progress.

 

`Gurobi 9.5.1 (win64, R) logging started Tue Jun 21 09:22:21 2022

Set parameter MIPGap to value 0.05
Set parameter LogFile to value "mylogfile.log"
Set parameter Threads to value 8
Gurobi Optimizer version 9.5.1 build v9.5.1rc2 (win64)
Thread count: 8 physical cores, 8 logical processors, using up to 8 threads
Optimize a model with 5068276 rows, 2798040 columns and 17245353 nonzeros
Model fingerprint: 0x3a663bea
Variable types: 265596 continuous, 2532444 integer (2532444 binary)
Coefficient statistics:
  Matrix range     [3e-03, 9e+02]
  Objective range  [3e-03, 4e-02]
  Bounds range     [1e+00, 8e+02]
  RHS range        [6e-02, 2e+03]
Presolve removed 666123 rows and 1329490 columns (presolve time = 6s) ...
Presolve removed 2584648 rows and 1766089 columns (presolve time = 10s) ...
Presolve removed 3063017 rows and 1766089 columns (presolve time = 15s) ...
Presolve removed 3063017 rows and 1766089 columns (presolve time = 20s) ...
Presolve removed 3118938 rows and 1766089 columns (presolve time = 25s) ...
Presolve removed 3118938 rows and 1766089 columns (presolve time = 30s) ...
Presolve removed 3118938 rows and 1766089 columns (presolve time = 35s) ...
Presolve removed 3118938 rows and 1766089 columns (presolve time = 40s) ...
Presolve removed 3118938 rows and 1766089 columns (presolve time = 45s) ...
Presolve removed 3118938 rows and 1766089 columns (presolve time = 50s) ...
Presolve removed 3118938 rows and 1766089 columns (presolve time = 55s) ...
Presolve removed 3118938 rows and 1766089 columns (presolve time = 61s) ...
Presolve removed 3118938 rows and 1766089 columns (presolve time = 65s) ...
Presolve removed 3118938 rows and 1766089 columns (presolve time = 75s) ...
Presolve removed 3118938 rows and 1769337 columns (presolve time = 75s) ...
Presolve removed 3119859 rows and 1769337 columns (presolve time = 80s) ...
Presolve removed 3119859 rows and 1769337 columns (presolve time = 85s) ...
Presolve removed 3119859 rows and 1769337 columns (presolve time = 90s) ...
Presolve removed 3119859 rows and 1769337 columns
Presolve time: 91.45s
Presolved: 1948417 rows, 1028703 columns, 7023541 nonzeros
Variable types: 14016 continuous, 1014687 integer (1014687 binary)
Found heuristic solution: objective -0.0000000

Deterministic concurrent LP optimizer: primal simplex, dual simplex, and barrier
Showing barrier log only...

Root barrier log...

Ordering time: 0.43s

Barrier statistics:
 Dense cols : 2256
 AA' NZ     : 7.880e+06
 Factor NZ  : 1.951e+07 (roughly 1.4 GB of memory)
 Factor Ops : 3.060e+09 (less than 1 second per iteration)
 Threads    : 6

                  Objective                Residual
Iter       Primal          Dual         Primal    Dual     Compl     Time
   0   8.83031470e+04  3.67801562e+06  3.24e+05 1.39e-02  1.81e+02   137s
   1   4.99851529e+04  3.90858020e+06  2.16e+05 8.80e-02  1.33e+02   138s
   2   2.01812644e+04  6.20770784e+06  7.93e+04 2.32e-01  7.63e+01   139s
   3   9.91361265e+02  5.59178647e+06  3.02e+03 3.63e+00  4.38e+00   141s
   4   5.09305893e+02  2.86821727e+06  1.30e+03 1.29e+00  1.56e+00   142s
   5   3.51463911e+02  1.19388252e+06  6.99e+02 4.98e-01  5.41e-01   143s
   6   2.37097220e+02  7.03622810e+05  3.08e+02 2.86e-01  2.55e-01   144s
   7   1.89082066e+02  1.77169119e+05  1.52e+02 3.83e-01  5.97e-02   146s
   8   1.50065109e+02  8.05079515e+04  3.07e+01 1.70e-01  2.32e-02   147s
   9   1.41449087e+02  4.39698447e+04  1.29e+01 1.24e-01  1.21e-02   148s
  10   1.36003646e+02  1.96039211e+04  6.43e+00 1.14e-01  5.21e-03   150s
  11   1.34204601e+02  5.93054215e+03  4.55e+00 1.01e-02  1.53e-03   151s
  12   1.30760828e+02  1.88586491e+03  1.24e+00 1.82e-03  4.51e-04   152s
  13   1.30543654e+02  1.36042339e+03  1.06e+00 1.45e-03  3.16e-04   153s
  14   1.30577492e+02  4.88248470e+02  7.92e-01 8.10e-04  9.22e-05   155s
  15   1.29899016e+02  1.81907069e+02  1.69e-03 1.86e-04  1.31e-05   156s
  16   1.29972281e+02  1.30029701e+02  1.20e-10 3.05e-07  1.45e-08   158s
  17   1.29973998e+02  1.29974056e+02  1.88e-11 1.64e-11  1.45e-11   159s
  18   1.29973999e+02  1.29974048e+02  1.56e-11 1.03e-08  1.23e-11   160s
  19   1.29973999e+02  1.29974043e+02  1.42e-11 2.93e-08  1.15e-11   161s
  20   1.29973999e+02  1.29974033e+02  1.24e-11 3.50e-08  8.93e-12   163s
  21   1.29974000e+02  1.29974023e+02  4.45e-12 3.23e-08  6.13e-12   164s
  22   1.29974000e+02  1.29974018e+02  2.07e-12 2.38e-08  4.81e-12   166s
  23   1.29974000e+02  1.29974017e+02  2.03e-12 3.62e-08  4.76e-12   168s
  24   1.29974000e+02  1.29974009e+02  1.94e-12 2.86e-07  4.69e-12   170s
  25   1.29974000e+02  1.29974001e+02  1.54e-12 1.66e-07  3.19e-12   171s
  26   1.29974000e+02  1.29974001e+02  1.43e-12 1.66e-07  3.19e-12   173s
  27   1.29974000e+02  1.29974001e+02  1.43e-12 2.23e-07  3.19e-12   174s

Barrier solved model in 27 iterations and 174.30 seconds (84.40 work units)
Optimal objective 1.29974000e+02


Root crossover log...

      13 DPushes remaining with DInf 0.0000000e+00               176s
       0 DPushes remaining with DInf 0.0000000e+00               177s

   50617 PPushes remaining with PInf 0.0000000e+00               177s
    4277 PPushes remaining with PInf 0.0000000e+00               207s
     208 PPushes remaining with PInf 0.0000000e+00               212s
       0 PPushes remaining with PInf 0.0000000e+00               214s

  Push phase complete: Pinf 0.0000000e+00, Dinf 0.0000000e+00    214s


Root simplex log...

Iteration    Objective       Primal Inf.    Dual Inf.      Time
   50633    1.2997400e+02   0.000000e+00   0.000000e+00    215s
   50633    1.2997400e+02   0.000000e+00   0.000000e+00    217s
Concurrent spin time: 9.63s

Solved with barrier

Root relaxation: objective 1.299740e+02, 50633 iterations, 103.47 seconds (57.67 work units)

    Nodes    |    Current Node    |     Objective Bounds      |     Work
 Expl Unexpl |  Obj  Depth IntInf | Incumbent    BestBd   Gap | It/Node Time

     0     0  129.97400    0 27370   -0.00000  129.97400      -     -  414s
     0     0  129.97400    0 17515   -0.00000  129.97400      -     - 2077s
H    0     0                       0.1275600  129.97400      -     - 2184s
     0     0  129.97400    0 17078    0.12756  129.97400      -     - 2349s
     0     0  129.97400    0 15964    0.12756  129.97400      -     - 3359s
H    0     0                       1.5930012  129.97400  8059%     - 3444s
H    0     0                       2.6202159  129.97400  4860%     - 3795s
     0     0  129.97400    0 15524    2.62022  129.97400  4860%     - 4146s
     0     0  129.97400    0 14692    2.62022  129.97400  4860%     - 5509s
H    0     0                      18.8285484  129.97400   590%     - 9206s
     0     0  129.97400    0 14525   18.82855  129.97400   590%     - 9665s
     0     0  129.97400    0 14136   18.82855  129.97400   590%     - 10953s
H    0     0                      19.1400019  129.97400   579%     - 11593s
     0     0  129.97400    0 12206   19.14000  129.97400   579%     - 11972s
     0     0  129.97400    0 11578   19.14000  129.97400   579%     - 12918s
     0     0  129.97400    0 10253   19.14000  129.97400   579%     - 13706s
     0     0  129.97400    0 10349   19.14000  129.97400   579%     - 14381s
H    0     0                      19.8170780  129.97400   556%     - 14434s
     0     0  129.97400    0 10228   19.81708  129.97400   556%     - 14651s
     0     0  129.97400    0 9674   19.81708  129.97400   556%     - 15343s
     0     0  129.97400    0 9631   19.81708  129.97400   556%     - 15680s
     0     0  129.97400    0 9512   19.81708  129.97400   556%     - 16421s
H    0     0                      21.1930857  129.97400   513%     - 16506s
     0     0  129.97400    0 9506   21.19309  129.97400   513%     - 16761s
     0     0  129.97400    0 9549   21.19309  129.97400   513%     - 17474s
     0     0  129.97400    0 9543   21.19309  129.97400   513%     - 17675s
     0     2  129.97400    0 9543   21.19309  129.97400   513%     - 20927s
     1     4  129.97400    1 9513   21.19309  129.97400   513%  7738 21545s
     3     8  129.97400    2 8865   21.19309  129.97400   513% 33000 22231s
     7    16  129.97400    3 8850   21.19309  129.97400   513% 40261 23026s
    15    24  129.97400    4 21920   21.19309  129.97400   513% 88916 23658s
    23    32  129.97400    4 8917   21.19309  129.97400   513% 122640 23724s
H   31    40                      25.0682481  129.97400   418% 97024 25664s
H   34    40                      25.3197620  129.97400   413% 89389 25665s
    39    48  129.97400    6 8888   25.31976  129.97400   413% 81524 25707s
    47    62  129.97400    7 8897   25.31976  129.97400   413% 71222 25783s
    61   120  129.97400    9 8873   25.31976  129.97400   413% 59510 26176s
   119   208  129.97400   19 8807   25.31976  129.97400   413% 39977 26959s
   130   208  129.97400   18 13196   25.31976  129.97400   413% 36862 26960s
H  207   292                      25.9871002  129.97400   400% 33492 27599s
H  218   292                      26.5375709  129.97400   390% 31949 27599s
H  240   292                      26.8791831  129.97400   384% 30791 27599s
H  271   292                      27.1791068  129.97400   378% 29246 27600s
   293   377  129.97400   40 8694   27.17911  129.97400   378% 30154 28262s
H  379   446                      28.3338817  129.97400   359% 27983 28749s
H  401   446                      29.1991904  129.97400   345% 26736 28749s
H  420   446                      30.8235564  129.97400   322% 26229 28749s
H  431   446                      32.7079464  129.97400   297% 25639 28750s
   452   526  129.97400   62 8634   32.70795  129.97400   297% 25660 29308s
H  537   607                      37.7409700  129.97400   244% 24137 29946s
H  543   607                      39.1001977  129.97400   232% 23918 29946s
H  554   607                      39.6870579  129.97400   227% 23608 29947s
H  565   607                      40.8413506  129.97400   218% 23162 29947s
   618   688  129.97400   79 8648   40.84135  129.97400   218% 22646 30687s
H  700   769                      47.3679727  129.97400   174% 21529 31412s
H  705   769                      47.5429806  129.97400   173% 21404 31413s
H  716   769                      47.7433208  129.97400   172% 21201 31413s
H  738   769                      50.9449877  129.97400   155% 20617 31413s
   781   846  129.97400   90 8683   50.94499  129.97400   155% 20099 31978s
H  859   854                      59.9018729  129.97400   117% 18998 33009s
H  861   854                      65.5923304  129.97400  98.2% 18969 33009s
   867   934  129.97400   95 8533   65.59233  129.97400  98.2% 18891 33447s
H  950   942                      67.9987166  129.97400  91.1% 17894 37492s
H  951   942                      69.6329037  129.97400  86.7% 17879 37492s
H  953   942                      70.6750281  129.97400  83.9% 17850 37492s
H  954   942                      73.7105384  129.97400  76.3% 17834 37493s
   958  1013  129.97400  105 8549   73.71054  129.97400  76.3% 17803 42225s
H 1032  1021                      74.2800689  129.97400  75.0% 17098 45513s
H 1033  1021                      76.6349958  129.97400  69.6% 17085 45513s
  1040  1109  129.97400  117 8551   76.63500  129.97400  69.6% 16989 45768s
  1128  1194  129.97400  128 8486   76.63500  129.97400  69.6% 15877 46067s
  1213  1281  129.97400  136 8474   76.63500  129.97400  69.6% 14951 46271s
  1301  1369  129.97400  146 8481   76.63500  129.97400  69.6% 14116 46460s
  1389  1457  129.97400  155 8542   76.63500  129.97400  69.6% 13381 46666s
  1477  1543  129.97400  166 8590   76.63500  129.97400  69.6% 12736 46862s
  1565  1630  129.97400  176 8559   76.63500  129.97400  69.6% 12168 47098s
  1652  1718  129.97400  187 8469   76.63500  129.97400  69.6% 11663 47297s
  1740  1799  129.97400  198 8435   76.63500  129.97400  69.6% 11202 47527s
  1822  1876  129.97400  208 8408   76.63500  129.97400  69.6% 10808 47763s
  1900  1963  129.97400  218 8476   76.63500  129.97400  69.6% 10463 47997s
  1988  2045  129.97400  227 8449   76.63500  129.97400  69.6% 10126 48132s
H 2076  2129                      76.8255641  129.97400  69.2%  9807 48370s
H 2107  2129                      77.4513932  129.97400  67.8%  9726 48371s
H 2129  2129                      79.4249210  129.97400  63.6%  9650 48371s
  2162  2208  129.97400  247 8532   79.42492  129.97400  63.6%  9527 48571s
  2244  2291  129.97400  252 8500   79.42492  129.97400  63.6%  9275 48744s
  2329  2378  129.97400  260 8520   79.42492  129.97400  63.6%  9032 48940s
  2416  2462  129.97400  270 8524   79.42492  129.97400  63.6%  8805 49123s
  2502  2544  129.97400  279 8511   79.42492  129.97400  63.6%  8599 49305s
  2584  2625  129.97400  286 8510   79.42492  129.97400  63.6%  8410 49505s
  2665  2707  129.97400  296 8465   79.42492  129.97400  63.6%  8243 49688s
  2747  2790  129.97400  301 8523   79.42492  129.97400  63.6%  8085 49869s
  2830  2874  129.97400  306 8414   79.42492  129.97400  63.6%  7928 50022s
  2917  2952  129.97400  317 8430   79.42492  129.97400  63.6%  7778 50214s
  2997  3031  129.97400  324 8464   79.42492  129.97400  63.6%  7644 50405s
  3076  3112  129.97400  333 8437   79.42492  129.97400  63.6%  7521 50598s
H 3157  3187                      81.5603216  129.97400  59.4%  7403 50827s
  3233  3256  129.97400  340 8396   81.56032  129.97400  59.4%  7311 51003s
  3303  3327  129.97400  345 8380   81.56032  129.97400  59.4%  7209 51194s
  3378  3390  129.97400  354 8367   81.56032  129.97400  59.4%  7102 51343s
  3441  3466  129.97400  357 8390   81.56032  129.97400  59.4%  7017 51557s
  3518  3547  129.97400  363 8380   81.56032  129.97400  59.4%  6929 51722s
  3599  3631  129.97400  372 8345   81.56032  129.97400  59.4%  6842 51893s
  3683  3699  129.97400  381 8370   81.56032  129.97400  59.4%  6757 52057s
  3751  3769  129.97400  384 8392   81.56032  129.97400  59.4%  6679 52233s
  3822  3839  129.97400  387 8404   81.56032  129.97400  59.4%  6605 52405s
  3892  3909  129.97400  391 8422   81.56032  129.97400  59.4%  6534 52576s
  3962  3988  129.97400  394 8440   81.56032  129.97400  59.4%  6462 52748s
  4042  4062  129.97400  397 8446   81.56032  129.97400  59.4%  6395 52918s
  4116  4132  129.97400  400 8590   81.56032  129.97400  59.4%  6335 53077s
H 4190  4211                      81.5648705  129.97400  59.4%  6274 53306s
H 4193  4211                      81.5986210  129.97400  59.3%  6273 53306s
H 4204  4211                      82.4750700  129.97400  57.6%  6279 53306s
  4270  4291  129.97400  404 8430   82.47507  129.97400  57.6%  6213 53503s
  4350  4362  129.97400  407 8731   82.47507  129.97400  57.6%  6155 53651s
  4422  4440  129.97400  409 8560   82.47507  129.97400  57.6%  6108 53817s
  4500  4520  129.97400  413 8582   82.47507  129.97400  57.6%  6058 53977s
  4580  4599  129.97400  419 8584   82.47507  129.97400  57.6%  6007 54127s
  4660  4672  129.97400  422 8526   82.47507  129.97400  57.6%  5958 54304s
  4736  4743  129.97400  426 8506   82.47507  129.97400  57.6%  5909 54535s
  4807  4808  129.97400  430 8464   82.47507  129.97400  57.6%  5865 54703s
  4872  4875  129.97400  432 8445   82.47507  129.97400  57.6%  5823 54857s
  4939  4945  129.97400  434 8435   82.47507  129.97400  57.6%  5781 55050s
  5011  5015  129.97400  437 8432   82.47507  129.97400  57.6%  5741 55261s
  5084  5087  129.97400  440 8433   82.47507  129.97400  57.6%  5701 55450s
  5164  5159  129.97400  443 8441   82.47507  129.97400  57.6%  5659 55629s
H 5236  5235                      82.7529905  129.97400  57.1%  5621 55809s
H 5238  5235                      83.1894097  129.97400  56.2%  5621 55809s
  5312  5305  129.97400  447 8443   83.18941  129.97400  56.2%  5584 55985s
  5382  5376  129.97400  449 8441   83.18941  129.97400  56.2%  5550 56148s
  5453  5453  129.97400  451 8493   83.18941  129.97400  56.2%  5517 56301s
  5531  5524  129.97400  453 8496   83.18941  129.97400  56.2%  5483 56463s
  5603  5592  129.97400  455 8487   83.18941  129.97400  56.2%  5453 56669s
  5671  5665  129.97400  458 8487   83.18941  129.97400  56.2%  5425 56808s
  5744  5731  129.97400  460 8480   83.18941  129.97400  56.2%  5396 57333s
  5810  5805  129.97400  461 8487   83.18941  129.97400  56.2%  5379 57539s
  5885  5878  129.97400  464 8498   83.18941  129.97400  56.2%  5347 57729s
  5962  5948  129.97400  466 8493   83.18941  129.97400  56.2%  5316 57927s
  6034  6017  129.97400  469 8594   83.18941  129.97400  56.2%  5288 58099s
  6104  6086  129.97400  471 8516   83.18941  129.97400  56.2%  5259 58311s
H 6177  6094                      84.8087342  129.97400  53.3%  5231 60544s
H 6184  6094                      84.8262992  129.97400  53.2%  5230 60545s
  6185  6161  129.97400  475 8502   84.82630  129.97400  53.2%  5229 60712s
  6253  6229  129.97400  477 8528   84.82630  129.97400  53.2%  5205 60921s
  6323  6299  129.97400  480 8431   84.82630  129.97400  53.2%  5177 61167s
  6394  6369  129.97400  483 8514   84.82630  129.97400  53.2%  5151 61339s
  6465  6432  129.97400  484 8513   84.82630  129.97400  53.2%  5128 61516s
  6528  6495  129.97400  486 8551   84.82630  129.97400  53.2%  5103 61725s
  6591  6562  129.97400  487 8542   84.82630  129.97400  53.2%  5080 61895s
  6662  6629  129.97400  489 8550   84.82630  129.97400  53.2%  5057 62090s
  6731  6699  129.97400  491 9349   84.82630  129.97400  53.2%  5033 62254s
  6802  6773  129.97400  492 9246   84.82630  129.97400  53.2%  5013 62412s
  6876  6847  129.97400  494 9275   84.82630  129.97400  53.2%  4986 62603s
  6950  6913  129.97400  496 9257   84.82630  129.97400  53.2%  4961 62764s
  7016  6984  129.97400  498 9211   84.82630  129.97400  53.2%  4935 62932s
  7088  7050  129.97400  499 9208   84.82630  129.97400  53.2%  4909 63122s
  7156  7124  129.97400  501 9152   84.82630  129.97400  53.2%  4882 63294s
H 7231  7124                      84.9191978  129.97400  53.1%  4857 65262s
  7232  7125  128.04629  963 9543   84.91920  129.97400  53.1%  4856 68579s
  7234  7126  129.97400  480 1107   84.91920  129.97400  53.1%  4855 73670s
  7235  7127  129.97400  363  807   84.91920  129.97400  53.1%  4854 83467s
H 7235  6770                      84.9894059  129.97400  52.9%  4854 85582s
  7236  6771  127.97447  456  990   84.98941  129.97400  52.9%  4853 85652s
  7237  6771  118.15762  986  834   84.98941  129.97400  52.9%  4853 95654s
  7238  6772  129.97400  791 1231   84.98941  129.97400  52.9%  4852 96001s
H 7238  6433                      85.0532161  129.97400  52.8%  4852 104326s
H 7238  6112                      85.0920524  129.97400  52.7%  4852 104327s
  7239  6113  129.97400  726  799   85.09205  129.97400  52.7%  4851 105124s
  7240  6113  129.97400  411 1575   85.09205  129.97400  52.7%  4851 105906s
  7241  6114  128.04629  968  584   85.09205  129.97400  52.7%  4850 130104s
  7242  6115  124.61704  444 1130   85.09205  129.97400  52.7%  4849 130270s`

0

Comments

3 comments

Date Votes
  • Maliheh Aramon
    Gurobi Staff Gurobi Staff

    Hi Ralph,

    You might want to experiment with the following:

    • The model is big. It has 2.5 million binary variables. It might be a good idea to ensure the presolved model is as small and as tight as possible. You can experiment with more aggressive settings for the parameters Presolve (2), Symmetry (2), and PreSparsify (1).
    • The log shows that the Gurobi Optimizer is struggling in finding a good incumbent quickly. You can consider experimenting with the parameter NoRelHeurTime which enforces the Gurobi Optimizer to run the NoRel (no relaxation) heuristic before the root relaxation. 
    • Bumping up the default value of the Heuristics parameter and turning off the Cuts (Cuts=0) are other ideas that you can experiment with. Setting Cuts=0 makes sense because the log shows that the bound does not move from the value obtained from the root relaxation.

    Best regards,

    Maliheh

    0
  • RALPH ASHER
    Gurobi-versary
    First Comment
    First Question

    Thank you Maliheh.  I'm running it now with Presolve=2, PreSparsify=1, Symmetry = 2,
    NoRelHeurTime=700,Cuts=0,Heuristics=0.3 in the parameters.  Aggressive Presolve took much longer, but it's exploring many more nodes in the same approximate time as before.

     

        Nodes    |    Current Node    |     Objective Bounds      |     Work
     Expl Unexpl |  Obj  Depth IntInf | Incumbent    BestBd   Gap | It/Node Time

         0     0  129.97400    0  753   -0.00000  129.97400      -     - 7988s
    H    0     0                       7.2810187  129.97400  1685%     - 7998s
    H    0     0                      16.4615871  129.97400   690%     - 8052s
         0     0  129.97400    0  567   16.46159  129.97400   690%     - 9777s
    H    0     0                      17.7285534  129.97400   633%     - 20042s
    H    0     0                      24.7837486  129.97400   424%     - 20243s
         0     2  129.97400    0  474   24.78375  129.97400   424%     - 20940s
         1     4  129.97400    1 1009   24.78375  129.97400   424% 60713 21161s
         3     8  129.97400    2  790   24.78375  129.97400   424% 45273 21217s
         7    16  129.97400    3  813   24.78375  129.97400   424% 21157 21419s
        15    24  129.97400    4  811   24.78375  129.97400   424% 17315 21503s
        23    32  129.97400    5  723   24.78375  129.97400   424% 12226 21534s
    H   31    40                      33.1828600  129.97400   292%  9387 22750s
    H   35    40                      39.8238175  129.97400   226%  8682 22750s
        39    48  129.97400    7  772   39.82382  129.97400   226%  8147 22774s
        47    60  129.97400    8  970   39.82382  129.97400   226%  7092 22880s
        59    88  129.97400    9  961   39.82382  129.97400   226%  6248 24440s
    H   64    88                      41.2301039  129.97400   215%  5847 24440s
    H   87   113                      41.7123821  129.97400   212% 11735 27186s
    H   98   113                      45.9968559  129.97400   183% 11101 27186s
    H  112   185                      47.0023530  129.97400   177% 12421 30039s
    H  120   185                      48.1180504  129.97400   170% 13344 30039s
       175   185  129.97400   12 3056   48.11805  129.97400   170% 12562 30040s
       184   272  129.97400   30 1094   48.11805  129.97400   170% 12877 32011s
    H  271   347                      49.3286311  129.97400   163% 11005 33184s
       346   411  129.97400   40  529   49.32863  129.97400   163%  9780 34932s
    H  410   471                      50.1459907  129.97400   159%  8770 38480s
    H  424   471                      52.5408294  129.97400   147%  8801 38480s
       470   559  129.97400   42  525   52.54083  129.97400   147%  8235 39051s
    H  558   647                      52.8061270  129.97400   146%  7268 39874s
    H  580   647                      52.8507362  129.97400   146%  7007 39874s

    0
  • Maliheh Aramon
    Gurobi Staff Gurobi Staff

    Hi Ralph, 

    I think you mean you used NoRelHeurTime=7000. It apparently did not help at all and could not find an incumbent better than the one found by a heuristic immediately after presolve. You might want to discard this parameter. 

    • The log again shows that the Gurobi is struggling to find a high quality incumbent. How hard is it  to construct a feasible solution for this problem using a local search type heuristic? If it is relatively easy, you might want to consider providing that as an initial solution to give Gurobi a good start for proving optimality.
    • You might also consider experimenting with parameters such as ImproveStartTime, ImproveStartGap, or ImproveStartNode to completely change the strategy of Gurobi and give up on proving optimality and see what the best feasible solution you might be able to get.

    Best regards,

    Maliheh

     

    0

Please sign in to leave a comment.

Didn't find what you were looking for?

New post