Improving solving (gap closing) time

Hi!

I have a task scheduling problem that I'm trying to solve using a MILP model. It closely resembles a VRPTW (Vehicle Routing Problem with Time Windows). I use binary decision variable \(x_{ijk}\), which is 1 if vehicle \(k\) travels from task \(i\) to \(j\), and binary decision variable \(y_{ik}\), which is 1 if vehicle \(k\) performs task \(i\). I have set a TimeLimit of 600, and I'm trying to obtain the best possible solution within those 10 minutes. To speed up the problem-solving process, I have already done several things:

• I only create decision variables that are "feasible." This has reduced the number of ij combinations by more than 90% (from 2,223,081 to 177,454). Additionally, there are many tasks that can only be performed by specific vehicles, which further reduces the number of ijk combinations by more than 95% (from 12,421,780 to 72,850). So, I have tried to make the model as "dense" as possible.

• I have tightly defined the lb and ub values of the continuous variables and the big M values used.

• I have tried to limit the coefficient statistics ranges. I believe these ranges are acceptable. However, the lb of the matrix range and objective range are slightly negative, whereas I expected a lb of 0 everywhere. I haven't been able to determine the cause of this yet. I set the IntegralityFocus parameter to 1 because, in some cases, a binary decision variable approached 0.999..., which didn't affect the objective value in the solution but did affect reading the variables afterward.

• I have written a heuristic to provide Gurobi with an initial feasible solution. It works well because it always produces an initial solution with a gap. However, it takes quite a long time to close that gap.

• I have varied the MIPFocus parameter (1, 2, and 3), but it doesn't make much of a difference. After 10 minutes, it doesn't result in more than a 1% difference in the gap.

Below, I have included the Gurobi log. I was wondering if anyone notices anything in the log that stands out or has suggestions for what I could do to speed up the solving process / gap closing?

During the solving of the root node, my computer is running at approximately 15-20% CPU usage and 20% RAM (6/32 GB). It doesn't seem to be the limiting factor. After solving the root node, CPU usage increases to varying levels between 50% and 100%, and RAM usage increases to 8.0 GB (25%).

Set parameter IntegralityFocus to value 1
Set parameter TimeLimit to value 600
Gurobi Optimizer version 10.0.1 build v10.0.1rc0 (win64)

CPU model: 11th Gen Intel(R) Core(TM) i7-11700 @ 2.50GHz, instruction set [SSE2|AVX|AVX2|AVX512]
Thread count: 8 physical cores, 16 logical processors, using up to 16 threads

Academic license - for non-commercial use only - registered to [...]
Optimize a model with 448041 rows, 165160 columns and 1632757 nonzeros
Model fingerprint: 0x9adce2cd
Variable types: 17940 continuous, 147220 integer (147220 binary)
Coefficient statistics:
  Matrix range     [3e-01, 1e+03]
  Objective range  [4e-01, 2e+02]
  Bounds range     [1e+00, 6e+02]
  RHS range        [1e+00, 2e+03]

Warning: Completing partial solution with 147116 unfixed non-continuous variables out of 147220
User MIP start produced solution with objective 16113.4 (1.28s)
User MIP start produced solution with objective 15976.6 (1.31s)
User MIP start produced solution with objective 15885.4 (1.79s)
User MIP start produced solution with objective 15793.9 (2.03s)
User MIP start produced solution with objective 15520.3 (2.26s)
User MIP start produced solution with objective 15425.7 (2.42s)
User MIP start produced solution with objective 15238.5 (3.01s)
User MIP start produced solution with objective 15010.3 (3.09s)
User MIP start produced solution with objective 14918.8 (3.18s)
User MIP start produced solution with objective 11972.5 (3.22s)
User MIP start produced solution with objective 11926.9 (3.31s)
User MIP start produced solution with objective 11920.5 (3.40s)
User MIP start produced solution with objective 11874.9 (3.91s)
User MIP start produced solution with objective 11869.1 (4.11s)
User MIP start produced solution with objective 11855.8 (4.32s)
User MIP start produced solution with objective 11855.8 (4.43s)
Loaded user MIP start with objective 11855.8
Processed MIP start in 4.43 seconds (4.39 work units)

Presolve removed 314558 rows and 124487 columns (presolve time = 5s) ...
Presolve removed 346168 rows and 137568 columns
Presolve time: 7.73s
Presolved: 101873 rows, 27592 columns, 756795 nonzeros
Variable types: 9980 continuous, 17612 integer (17588 binary)

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

Root barrier log...

Ordering time: 3.74s

Barrier statistics:
 Dense cols : 1
 AA' NZ     : 8.347e+06
 Factor NZ  : 7.953e+07 (roughly 700 MB of memory)
 Factor Ops : 8.681e+10 (roughly 1 second per iteration)
 Threads    : 6

                  Objective                Residual
Iter       Primal          Dual         Primal    Dual     Compl     Time
   0   1.60237074e+06 -9.14336501e+05  1.15e+04 1.11e+00  3.49e+02    19s
   1   9.61125017e+05 -1.58838518e+06  6.94e+03 3.36e+00  1.92e+02    19s
   2   4.74942636e+05 -2.15345397e+06  3.35e+03 3.96e-01  8.86e+01    20s
   3   1.13003525e+05 -1.35985557e+06  6.92e+02 7.12e-13  2.05e+01    21s
   4   2.98269526e+04 -4.08891749e+05  1.06e+02 4.75e-13  3.74e+00    22s
   5   1.06150785e+04 -6.93610387e+04  8.57e+00 4.55e-13  5.60e-01    23s
   6   6.19254334e+03 -1.46660857e+04  1.32e+00 4.55e-13  1.40e-01    24s
   7   5.02695393e+03 -4.63263751e+03  7.35e-01 3.39e-13  6.48e-02    25s
   8   4.53794584e+03 -3.63807528e+02  5.29e-01 2.29e-13  3.28e-02    26s
   9   4.28559121e+03  4.83829777e+02  4.18e-01 3.53e-13  2.54e-02    27s
  10   4.19804627e+03  1.03706008e+03  3.77e-01 3.27e-13  2.11e-02    27s
  11   3.87457855e+03  2.00585246e+03  2.37e-01 3.47e-13  1.25e-02    28s
  12   3.74777556e+03  2.60206837e+03  1.81e-01 2.42e-13  7.63e-03    29s
  13   3.58752064e+03  2.98259375e+03  1.10e-01 2.36e-13  4.02e-03    30s
  14   3.48197452e+03  3.17579897e+03  6.00e-02 3.33e-13  2.04e-03    31s
  15   3.44443566e+03  3.23784357e+03  4.48e-02 2.67e-13  1.37e-03    32s
  16   3.43564158e+03  3.24870029e+03  4.05e-02 2.31e-13  1.24e-03    33s
  17   3.39618455e+03  3.27990990e+03  2.32e-02 2.71e-13  7.73e-04    34s
  18   3.36884508e+03  3.33006412e+03  9.36e-03 4.04e-13  2.58e-04    35s
  19   3.36123905e+03  3.34739752e+03  5.79e-03 3.02e-13  9.18e-05    36s
  20   3.35320374e+03  3.34881649e+03  1.66e-03 3.38e-13  2.91e-05    37s
  21   3.35050757e+03  3.34900661e+03  2.88e-04 3.03e-13  9.98e-06    38s
  22   3.35000302e+03  3.34955246e+03  4.02e-05 3.03e-13  3.00e-06    39s
  23   3.34991944e+03  3.34991594e+03  5.27e-08 3.17e-13  2.33e-08    39s
  24   3.34991931e+03  3.34991912e+03  1.90e-07 3.71e-13  1.24e-09    40s
  25   3.34991920e+03  3.34991920e+03  4.12e-09 3.60e-13  1.44e-12    41s

Barrier solved model in 25 iterations and 41.34 seconds (44.83 work units)
Optimal objective 3.34991920e+03


Root crossover log...

    6855 DPushes remaining with DInf 0.0000000e+00                41s
       0 DPushes remaining with DInf 0.0000000e+00                41s

    2837 PPushes remaining with PInf 1.0845740e-04                41s
       0 PPushes remaining with PInf 0.0000000e+00                42s

  Push phase complete: Pinf 0.0000000e+00, Dinf 2.0740416e-11     42s


Root simplex log...

Iteration    Objective       Primal Inf.    Dual Inf.      Time
    6719    3.3499192e+03   0.000000e+00   0.000000e+00     42s
    6719    3.3499192e+03   0.000000e+00   0.000000e+00     42s
Concurrent spin time: 1.04s

Solved with barrier

Root relaxation: objective 3.349919e+03, 6719 iterations, 29.81 seconds (30.02 work units)
Total elapsed time = 47.96s

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

     0     0 3349.91920    0 1017 11855.7800 3349.91920  71.7%     -   50s
     0     0 3349.91920    0  970 11855.7800 3349.91920  71.7%     -   51s
     0     0 3384.39095    0 1228 11855.7800 3384.39095  71.5%     -   57s
H    0     0                    11816.430000 3384.39095  71.4%     -   57s
     0     0 3409.42576    0 1103 11816.4300 3409.42576  71.1%     -   60s
     0     0 3409.42576    0 1072 11816.4300 3409.42576  71.1%     -   61s
     0     0 3480.47871    0 1222 11816.4300 3480.47871  70.5%     -   72s
     0     0 3483.84085    0 1250 11816.4300 3483.84085  70.5%     -   75s
     0     0 3485.17766    0 1246 11816.4300 3485.17766  70.5%     -   76s
     0     0 3485.26550    0 1228 11816.4300 3485.26550  70.5%     -   77s
     0     0 3485.26857    0 1193 11816.4300 3485.26857  70.5%     -   77s
     0     0 3642.60629    0 1459 11816.4300 3642.60629  69.2%     -   91s
     0     0 3663.25691    0 1419 11816.4300 3663.25691  69.0%     -   94s
     0     0 3666.94703    0 1400 11816.4300 3666.94703  69.0%     -   95s
     0     0 3668.99146    0 1556 11816.4300 3668.99146  69.0%     -   97s
     0     0 3669.09141    0 1510 11816.4300 3669.09141  68.9%     -   97s
     0     0 3669.18538    0 1515 11816.4300 3669.18538  68.9%     -   98s
     0     0 3669.18538    0 1517 11816.4300 3669.18538  68.9%     -   98s
     0     0 3824.27303    0 2215 11816.4300 3824.27303  67.6%     -  110s
     0     0 3835.07681    0 1992 11816.4300 3835.07681  67.5%     -  116s
     0     0 3835.45285    0 2084 11816.4300 3835.45285  67.5%     -  119s
     0     0 3835.49373    0 2085 11816.4300 3835.49373  67.5%     -  120s
     0     0 3878.38964    0 2238 11816.4300 3878.38964  67.2%     -  132s
     0     0 3884.85528    0 2256 11816.4300 3884.85528  67.1%     -  136s
     0     0 3885.01647    0 2246 11816.4300 3885.01647  67.1%     -  138s
     0     0 3885.06370    0 2240 11816.4300 3885.06370  67.1%     -  139s
     0     0 3900.70213    0 2145 11816.4300 3900.70213  67.0%     -  149s
     0     0 3902.33752    0 2273 11816.4300 3902.33752  67.0%     -  153s
     0     0 3902.33752    0 2239 11816.4300 3902.33752  67.0%     -  155s
     0     0 3913.71840    0 1606 11816.4300 3913.71840  66.9%     -  163s
     0     0 3915.68971    0 1643 11816.4300 3915.68971  66.9%     -  166s
     0     0 3916.32175    0 1531 11816.4300 3916.32175  66.9%     -  168s
     0     0 3916.32447    0 1634 11816.4300 3916.32447  66.9%     -  170s
     0     0 3927.46489    0 1920 11816.4300 3927.46489  66.8%     -  176s
     0     0 3927.57449    0 1942 11816.4300 3927.57449  66.8%     -  178s
     0     0 3927.91886    0 1979 11816.4300 3927.91886  66.8%     -  179s
     0     0 3927.92061    0 1955 11816.4300 3927.92061  66.8%     -  180s
     0     0 3931.71526    0 1990 11816.4300 3931.71526  66.7%     -  184s
     0     0 3932.06141    0 2032 11816.4300 3932.06141  66.7%     -  186s
     0     0 3932.06449    0 1983 11816.4300 3932.06449  66.7%     -  186s
     0     0 3948.79076    0 2031 11816.4300 3948.79076  66.6%     -  192s
     0     0 3948.89053    0 2052 11816.4300 3948.89053  66.6%     -  194s
     0     0 3948.92035    0 1989 11816.4300 3948.92035  66.6%     -  194s
     0     0 3972.75435    0 2012 11816.4300 3972.75435  66.4%     -  208s
     0     0 3973.37801    0 2014 11816.4300 3973.37801  66.4%     -  209s
     0     0 3974.50630    0 1980 11816.4300 3974.50630  66.4%     -  211s
     0     0 3974.50630    0 1960 11816.4300 3974.50630  66.4%     -  211s
     0     0 3983.27270    0 1947 11816.4300 3983.27270  66.3%     -  217s
     0     0 3983.64854    0 1989 11816.4300 3983.64854  66.3%     -  218s
     0     0 3983.73473    0 2034 11816.4300 3983.73473  66.3%     -  219s
     0     0 3991.39333    0 2712 11816.4300 3991.39333  66.2%     -  226s
     0     0 3991.95135    0 2765 11816.4300 3991.95135  66.2%     -  227s
     0     0 3992.37994    0 2757 11816.4300 3992.37994  66.2%     -  228s
     0     0 3992.37994    0 2728 11816.4300 3992.37994  66.2%     -  229s
     0     0 4000.07004    0 2155 11816.4300 4000.07004  66.1%     -  238s
     0     0 4000.27381    0 2598 11816.4300 4000.27381  66.1%     -  241s
     0     0 4000.29300    0 2638 11816.4300 4000.29300  66.1%     -  242s
     0     0 4003.18420    0 2758 11816.4300 4003.18420  66.1%     -  246s
     0     0 4003.37361    0 2785 11816.4300 4003.37361  66.1%     -  248s
     0     0 4003.41716    0 2741 11816.4300 4003.41716  66.1%     -  248s
     0     0 4004.34756    0 2692 11816.4300 4004.34756  66.1%     -  253s
     0     0 4004.93848    0 2716 11816.4300 4004.93848  66.1%     -  255s
     0     0 4004.94413    0 2709 11816.4300 4004.94413  66.1%     -  255s
     0     0 4006.41173    0 2104 11816.4300 4006.41173  66.1%     -  258s
     0     0 4007.24054    0 2228 11816.4300 4007.24054  66.1%     -  260s
     0     0 4007.44081    0 2215 11816.4300 4007.44081  66.1%     -  260s
     0     0 4007.45814    0 2185 11816.4300 4007.45814  66.1%     -  261s
     0     0 4013.01266    0 2306 11816.4300 4013.01266  66.0%     -  264s
H    0     0                    11815.930000 4013.01266  66.0%     -  264s
     0     0 4013.40464    0 2349 11815.9300 4013.40464  66.0%     -  265s
     0     0 4013.92785    0 2353 11815.9300 4013.92785  66.0%     -  266s
     0     0 4013.93213    0 2326 11815.9300 4013.93213  66.0%     -  266s
     0     0 4018.26654    0 2171 11815.9300 4018.26654  66.0%     -  268s
     0     0 4018.58875    0 2210 11815.9300 4018.58875  66.0%     -  269s
     0     0 4018.61983    0 2268 11815.9300 4018.61983  66.0%     -  270s
     0     0 4021.59136    0 2234 11815.9300 4021.59136  66.0%     -  272s
H    0     0                    11815.430000 4021.59136  66.0%     -  273s
     0     0 4022.04188    0 2196 11815.4300 4022.04188  66.0%     -  274s
     0     0 4022.11895    0 2281 11815.4300 4022.11895  66.0%     -  274s
     0     0 4024.04822    0 2241 11815.4300 4024.04822  65.9%     -  277s
H    0     0                    11801.950000 4024.04822  65.9%     -  277s
     0     0 4024.18060    0 2269 11801.9500 4024.18060  65.9%     -  278s
     0     0 4024.20050    0 2251 11801.9500 4024.20050  65.9%     -  278s
     0     0 4027.28261    0 2288 11801.9500 4027.28261  65.9%     -  280s
H    0     0                    11777.970000 4027.28261  65.8%     -  280s
     0     0 4027.38849    0 2583 11777.9700 4027.38849  65.8%     -  281s
     0     0 4031.41317    0 2263 11777.9700 4031.41317  65.8%     -  284s
     0     0 4032.46909    0 2308 11777.9700 4032.46909  65.8%     -  286s
     0     0 4032.83604    0 2264 11777.9700 4032.83604  65.8%     -  286s
     0     0 4032.89606    0 2242 11777.9700 4032.89606  65.8%     -  287s
     0     0 4038.92042    0 2172 11777.9700 4038.92042  65.7%     -  290s
     0     0 4039.83008    0 2225 11777.9700 4039.83008  65.7%     -  291s
     0     0 4039.99123    0 2279 11777.9700 4039.99123  65.7%     -  292s
     0     0 4040.10993    0 2284 11777.9700 4040.10993  65.7%     -  293s
     0     0 4040.11864    0 2268 11777.9700 4040.11864  65.7%     -  293s
     0     0 4065.48065    0 2231 11777.9700 4065.48065  65.5%     -  296s
     0     0 4065.84000    0 2306 11777.9700 4065.84000  65.5%     -  298s
     0     0 4065.85824    0 2306 11777.9700 4065.85824  65.5%     -  298s
     0     0 4070.13335    0 2283 11777.9700 4070.13335  65.4%     -  300s
     0     0 4071.25093    0 2357 11777.9700 4071.25093  65.4%     -  302s
     0     0 4071.46472    0 2300 11777.9700 4071.46472  65.4%     -  302s
     0     0 4071.49297    0 2329 11777.9700 4071.49297  65.4%     -  303s
     0     0 4072.01566    0 2270 11777.9700 4072.01566  65.4%     -  304s
     0     0 4073.06035    0 2252 11777.9700 4073.06035  65.4%     -  305s
     0     0 4073.10779    0 2274 11777.9700 4073.10779  65.4%     -  305s
     0     0 4077.98432    0 2240 11777.9700 4077.98432  65.4%     -  309s
     0     0 4078.47063    0 2189 11777.9700 4078.47063  65.4%     -  310s
     0     0 4078.49405    0 2186 11777.9700 4078.49405  65.4%     -  310s
     0     0 4081.33991    0 2356 11777.9700 4081.33991  65.3%     -  312s
     0     0 4082.75297    0 2576 11777.9700 4082.75297  65.3%     -  314s
     0     0 4082.89689    0 2347 11777.9700 4082.89689  65.3%     -  314s
     0     0 4082.90448    0 2334 11777.9700 4082.90448  65.3%     -  315s
     0     0 4083.82721    0 2318 11777.9700 4083.82721  65.3%     -  317s
     0     0 4083.90174    0 2419 11777.9700 4083.90174  65.3%     -  317s
     0     0 4085.48991    0 2067 11777.9700 4085.48991  65.3%     -  320s
     0     0 4087.07295    0 2137 11777.9700 4087.07295  65.3%     -  321s
     0     0 4087.11329    0 2296 11777.9700 4087.11329  65.3%     -  321s
     0     0 4090.25529    0 2158 11777.9700 4090.25529  65.3%     -  323s
H    0     0                    11757.110000 4090.25529  65.2%     -  323s
     0     0 4091.62976    0 2216 11757.1100 4091.62976  65.2%     -  324s
     0     0 4091.67086    0 2232 11757.1100 4091.67086  65.2%     -  324s
     0     0 4093.59627    0 2358 11757.1100 4093.59627  65.2%     -  326s
H    0     0                    11752.870000 4093.59627  65.2%     -  326s
     0     0 4097.68856    0 2278 11752.8700 4097.68856  65.1%     -  328s
     0     0 4098.03550    0 2315 11752.8700 4098.03550  65.1%     -  329s
     0     0 4098.07384    0 2343 11752.8700 4098.07384  65.1%     -  329s
     0     0 4098.27109    0 2303 11752.8700 4098.27109  65.1%     -  330s
     0     0 4098.28860    0 2332 11752.8700 4098.28860  65.1%     -  331s
     0     0 4103.75986    0 2371 11752.8700 4103.75986  65.1%     -  333s
     0     0 4104.10535    0 2394 11752.8700 4104.10535  65.1%     -  334s
     0     0 4104.28249    0 2338 11752.8700 4104.28249  65.1%     -  335s
     0     0 4104.31421    0 2363 11752.8700 4104.31421  65.1%     -  335s
     0     0 4104.88139    0 2385 11752.8700 4104.88139  65.1%     -  336s
H    0     0                    11752.370000 4104.88139  65.1%     -  337s
     0     0 4104.88850    0 2326 11752.3700 4104.88850  65.1%     -  337s
     0     0 4105.07649    0 2271 11752.3700 4105.07649  65.1%     -  338s
     0     0 4109.59719    0 2089 11752.3700 4109.59719  65.0%     -  341s
H    0     0                    11751.450000 4109.59719  65.0%     -  347s
     0     2 4109.59719    0 2089 11751.4500 4109.59719  65.0%     -  349s
     3     8 4110.39519    2 2213 11751.4500 4110.39519  65.0%  1041  351s
     7    14 4129.67543    3 2239 11751.4500 4110.39519  65.0%  1188  355s
    15    22 4129.73274    4 2315 11751.4500 4119.55452  64.9%  1514  360s
    23    28 4144.22713    5 2235 11751.4500 4119.55452  64.9%  2071  369s
    31    36 4156.97963    6 1752 11751.4500 4119.60759  64.9%  2324  375s
H   33    36                    11731.970000 4119.60759  64.9%  2307  375s
    47    58 4156.97963    7 1753 11731.9700 4121.75337  64.9%  2003  389s
    61    72 4157.28885    8 2214 11731.9700 4121.75337  64.9%  1658  392s
H   75    82                    11658.350000 4121.75337  64.6%  1475  395s
H   79    82                    11635.130000 4121.75337  64.6%  1408  395s
   103   112 4178.87069   13 2069 11635.1300 4121.75337  64.6%  1288  402s
   118   119 4178.91771   14 2065 11635.1300 4121.75337  64.6%  1195  407s
H  120   119                    11525.730000 4121.75337  64.2%  1221  407s
H  121   119                    11463.710000 4121.75337  64.0%  1211  407s
   130   133 4230.63895   15 1132 11463.7100 4121.75337  64.0%  1262  414s
   144   142 4208.63576   16 1220 11463.7100 4121.75337  64.0%  1258  421s
H  157   150                    11461.570000 4121.75337  64.0%  1294  432s
H  159   150                    11278.640000 4121.75337  63.5%  1299  432s
   165   167 4216.71559   17 1212 11278.6400 4121.75337  63.5%  1367  437s
   182   189 4225.72752   19 1176 11278.6400 4121.75337  63.5%  1381  445s
H  204   197                    11233.340000 4121.75337  63.3%  1374  461s
H  205   197                    11221.300000 4121.75337  63.3%  1376  461s
H  206   197                    11207.780000 4121.75337  63.2%  1383  461s
   212   215 4243.70736   20 1208 11207.7800 4121.75337  63.2%  1437  467s
   232   237 4252.48667   22 1182 11207.7800 4121.75337  63.2%  1448  493s
H  255   237                    11187.660000 4121.75337  63.2%  1433  493s
   258   267 4260.98090   24 1171 11187.6600 4121.75337  63.2%  1436  501s
H  288   275                    11167.640000 4121.75337  63.1%  1442  531s
   296   301 4306.85184   28 1187 11167.6400 4121.75337  63.1%  1472  538s
   326   333 infeasible   29      11167.6400 4121.75337  63.1%  1425  544s
   366   378 4329.13243   33 1122 11167.6400 4121.75337  63.1%  1336  550s
   421   413 4372.67693   40 1103 11167.6400 4121.75337  63.1%  1228  556s
   460   445 4383.68745   44 1078 11167.6400 4121.75337  63.1%  1178  563s
   504   465 4404.76867   46 1035 11167.6400 4121.75337  63.1%  1141  572s
   524   515 4426.30743   49 1112 11167.6400 4121.75337  63.1%  1125  579s
   575   547 4470.73100   52 1080 11167.6400 4121.75337  63.1%  1082  587s
   611   566 infeasible   54      11167.6400 4122.26422  63.1%  1072  595s
   640   577 4150.30582    6 1675 11167.6400 4122.26422  63.1%  1085  600s

Cutting planes:
  Learned: 15
  Gomory: 4
  Cover: 120
  Implied bound: 985
  Clique: 248
  MIR: 3014
  StrongCG: 174
  Flow cover: 653
  GUB cover: 5
  Zero half: 34
  Mod-K: 3
  Network: 1
  RLT: 450
  Relax-and-lift: 333

Explored 657 nodes (1050347 simplex iterations) in 600.22 seconds (1541.77 work units)
Thread count was 16 (of 16 available processors)

Solution count 10: 11167.6 11187.7 11207.8 ... 11635.1

Time limit reached
Best objective 1.116764000000e+04, best bound 4.122264217516e+03, gap 63.0874%

Thanks in advance!

Best regards,

Koen Timmermans