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Status SUBOPTIMAL

Ongoing

Comments

2 comments

  • Lennart Lahrs
    Gurobi Staff Gurobi Staff

    Hi Gabriel,

    Sequentially solving your model for different objectives rather than solving your model for one combined objective can have a strong influence on model performance and solving behavior. Note that for each objective, a new optimization is run, for which you can specify solver parameters, such as a time limit, which could result in early termination and, thereby, a sub-optimal solution.
    Feel free to share a log file from one of these runs, which might contain enough information to spot the issue.

    Best regards,
    Lennart

    0
  • Gabriel Pimenta
    First Comment
    First Question

    Thank you, Lennart.

    However, I have a question. When running the model with a short 'TimeLimit', the result is worse than running the model with a long 'TimeLimit', but both runs return an 'optimal' status. How is the status calculated, and why does it sometimes identify it as suboptimal and other times not?

    Also, here is the log of the executed run:

    Optimize a model with 49196 rows, 88668 columns and 6146061 nonzeros
    Model fingerprint: 0x8f08c33c
    Variable types: 6468 continuous, 82200 integer (82200 binary)
    Coefficient statistics:
      Matrix range     [2e-03, 7e+06]
      Objective range  [1e+00, 2e+07]
      Bounds range     [1e+00, 1e+00]
      RHS range        [2e-03, 2e+08]

    ---------------------------------------------------------------------------
    Multi-objectives: starting optimization with 3 objectives ...
    ---------------------------------------------------------------------------

    Multi-objectives: applying initial presolve ...
    ---------------------------------------------------------------------------

    Presolve removed 40168 rows and 74801 columns
    Presolve time: 4.64s
    Presolved: 9028 rows and 13867 columns
    ---------------------------------------------------------------------------

    Multi-objectives: optimize objective 1  ...
    ---------------------------------------------------------------------------

    Presolve removed 303 rows and 1332 columns
    Presolve time: 0.58s
    Presolved: 8725 rows, 12535 columns, 284114 nonzeros
    Variable types: 2580 continuous, 9955 integer (9865 binary)
    Deterministic concurrent LP optimizer: primal and dual simplex
    Showing first log only...


    Root simplex log...

    Iteration    Objective       Primal Inf.    Dual Inf.      Time
           0    1.2821345e+11   1.042746e+04   3.052648e+10      6s
    Concurrent spin time: 0.00s

    Solved with dual simplex

    Root simplex log...

    Iteration    Objective       Primal Inf.    Dual Inf.      Time
        2787    4.0407948e+08   0.000000e+00   0.000000e+00      6s

    Use crossover to convert LP symmetric solution to basic solution...

    Root crossover log...

           0 DPushes remaining with DInf 0.0000000e+00                 6s

         412 PPushes remaining with PInf 0.0000000e+00                 6s
           0 PPushes remaining with PInf 0.0000000e+00                 6s

      Push phase complete: Pinf 0.0000000e+00, Dinf 2.4965473e+06      6s


    Root simplex log...

    Iteration    Objective       Primal Inf.    Dual Inf.      Time
        3645    4.0407948e+08   0.000000e+00   2.496547e+06      6s
        3667    4.0407948e+08   0.000000e+00   0.000000e+00      6s
        3667    4.0407948e+08   0.000000e+00   0.000000e+00      6s

    Root relaxation: objective 4.040795e+08, 3667 iterations, 0.30 seconds (0.32 work units)

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

         0     0 4.0408e+08    0  149          - 4.0408e+08      -     -    5s
         0     0 4.0545e+08    0  180          - 4.0545e+08      -     -    7s
         0     0 4.0545e+08    0  203          - 4.0545e+08      -     -    8s
         0     0 4.0545e+08    0  209          - 4.0545e+08      -     -    9s
         0     0 4.0545e+08    0  194          - 4.0545e+08      -     -   10s
         0     0 4.0989e+08    0  103          - 4.0989e+08      -     -   12s
         0     0 4.0989e+08    0  140          - 4.0989e+08      -     -   12s
         0     0 4.0989e+08    0   88          - 4.0989e+08      -     -   13s
         0     0 4.0989e+08    0  156          - 4.0989e+08      -     -   13s
         0     0 4.0989e+08    0   73          - 4.0989e+08      -     -   13s
         0     0 4.0989e+08    0  118          - 4.0989e+08      -     -   14s
         0     0 4.0989e+08    0   68          - 4.0989e+08      -     -   14s
         0     0 4.0989e+08    0  155          - 4.0989e+08      -     -   14s
         0     0 4.0989e+08    0   79          - 4.0989e+08      -     -   15s
         0     0 4.0989e+08    0   55          - 4.0989e+08      -     -   15s
         0     2 4.0989e+08    0   55          - 4.0989e+08      -     -   17s
        72    81 4.1881e+08    9  177          - 4.0994e+08      -  48.9   26s
       508   562 4.3091e+08   59  128          - 4.0994e+08      -  64.3   30s
      2181  2278 4.9509e+08  254   27          - 4.0994e+08      -  35.5   40s
    * 2197  1566             227    4.403017e+08 4.0994e+08  6.90%  35.8   40s
    H 2341  1425                    4.402616e+08 4.0998e+08  6.88%  35.6   41s
    H 2447  1495                    4.402216e+08 4.0998e+08  6.87%  35.9   42s
      2450  1497 4.1233e+08  101  181 4.4022e+08 4.0998e+08  6.87%  35.8   45s
      2468  1518 4.1860e+08   15  345 4.4022e+08 4.0998e+08  6.87%   3.1   50s
      2565  1576 4.2288e+08   21  401 4.4022e+08 4.0998e+08  6.87%   4.8   55s
      2701  1672 4.2636e+08   30  412 4.4022e+08 4.0998e+08  6.87%   7.9   60s
      2952  1830 4.2681e+08   51  475 4.4022e+08 4.0998e+08  6.87%  13.6   65s
    H 3216  1694                    4.218624e+08 4.0998e+08  2.82%  18.1   69s
      3250  1651     cutoff   61      4.2186e+08 4.0998e+08  2.82%  18.2   73s
    H 3255  1572                    4.196034e+08 4.0998e+08  2.29%  18.1   73s
    H 3256  1503                    4.195633e+08 4.0998e+08  2.28%  18.1   73s
      3345  1572 4.1073e+08   25  172 4.1956e+08 4.0998e+08  2.28%  19.6   75s
      3966  1937 4.1241e+08  106  110 4.1956e+08 4.0998e+08  2.28%  21.6   80s
    H 4034  1850                    4.195185e+08 4.0998e+08  2.27%  22.6   80s
    H 4356  1975                    4.195175e+08 4.0998e+08  2.27%  23.6   83s
      4573  2138 4.1919e+08  194   27 4.1952e+08 4.0998e+08  2.27%  24.3   85s
      5099  2383 4.1069e+08   55  157 4.1952e+08 4.0998e+08  2.27%  32.3   90s
    H 5606  2554                    4.193171e+08 4.0998e+08  2.23%  35.1   94s
      5746  2721 4.1244e+08  136  103 4.1932e+08 4.0998e+08  2.23%  34.9   95s
      6350  3182 4.1517e+08  239   37 4.1932e+08 4.0998e+08  2.23%  35.5  100s
      6911  3521 4.1897e+08   42  118 4.1932e+08 4.0998e+08  2.23%  41.8  106s
    H 6926  3488                    4.192771e+08 4.0998e+08  2.22%  41.7  106s
    H 6936  3488                    4.192771e+08 4.0998e+08  2.22%  41.7  106s
      7265  3880 4.1042e+08   50  221 4.1928e+08 4.0998e+08  2.22%  45.2  110s
      7903  4355 4.1013e+08   33  219 4.1928e+08 4.0998e+08  2.22%  46.7  116s
      8415  4716 4.1307e+08   87  220 4.1928e+08 4.0998e+08  2.22%  47.3  121s
      8895  5280 4.1113e+08   55  140 4.1928e+08 4.0998e+08  2.22%  45.9  126s
      9233  5446     cutoff  101      4.1928e+08 4.0998e+08  2.22%  45.6  146s
      9768  5871 4.1713e+08   86  127 4.1928e+08 4.1000e+08  2.21%  46.5  152s
     10049  6124 4.1151e+08   37   96 4.1928e+08 4.1000e+08  2.21%  46.9  155s
     10797  6601 4.1043e+08   53  191 4.1928e+08 4.1000e+08  2.21%  50.3  165s
     11005  7024 4.1160e+08   66  154 4.1928e+08 4.1000e+08  2.21%  51.8  170s
     12141  8089 4.1172e+08   85  182 4.1928e+08 4.1000e+08  2.21%  52.5  180s
     12881  8496     cutoff  187      4.1928e+08 4.1000e+08  2.21%  51.9  310s
     13408  8726 4.1202e+08   64  234 4.1928e+08 4.1000e+08  2.21%  52.2  329s
    H13428  8726                    4.192771e+08 4.1000e+08  2.21%  52.1  329s
     13694  9501 4.1352e+08   84  187 4.1928e+08 4.1000e+08  2.21%  52.3  335s
     14593 10282 4.1021e+08   29  236 4.1928e+08 4.1000e+08  2.21%  50.1  343s

    Cutting planes:
      Gomory: 2
      Clique: 3

    Explored 15691 nodes (851881 simplex iterations) in 344.77 seconds (468.22 work units)
    Thread count was 16 (of 16 available processors)

    Solution count 10: 4.19277e+08 4.19277e+08 4.19317e+08 ... 4.40262e+08

    Time limit reached
    Best objective 4.192770688823e+08, best bound 4.100029548488e+08, gap 2.2119%
    ---------------------------------------------------------------------------

    Multi-objectives: optimize objective 2  ...
    ---------------------------------------------------------------------------


    Loaded user MIP start with objective 1

    Presolve removed 111 rows and 1323 columns
    Presolve time: 0.60s
    Presolved: 8918 rows, 12544 columns, 292718 nonzeros
    Variable types: 2568 continuous, 9976 integer (9880 binary)
    Root relaxation presolved: 8727 rows, 12686 columns, 284147 nonzeros

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


    Root simplex log...

    Iteration    Objective       Primal Inf.    Dual Inf.      Time
           0    0.0000000e+00   1.085131e+05   4.913600e+11    346s

    Solved with dual simplex

    Root simplex log...

    Iteration    Objective       Primal Inf.    Dual Inf.      Time
        4613    3.6803195e-01   0.000000e+00   0.000000e+00    346s

    Root relaxation: objective 3.680319e-01, 4613 iterations, 0.52 seconds (0.55 work units)

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

         0     0    0.36803    0  223    1.00000    0.36803  63.2%     -  346s
         0     0    0.37521    0  248    1.00000    0.37521  62.5%     -  348s
         0     0    0.37521    0  253    1.00000    0.37521  62.5%     -  348s
    H    0     0                       0.6485719    0.37521  42.1%     -  349s
         0     0    0.37521    0  204    0.64857    0.37521  42.1%     -  349s
         0     0    0.37535    0  210    0.64857    0.37535  42.1%     -  350s
         0     0    0.37535    0  256    0.64857    0.37535  42.1%     -  351s
         0     0    0.37546    0  249    0.64857    0.37546  42.1%     -  351s
         0     0    0.37546    0  304    0.64857    0.37546  42.1%     -  351s
         0     0    0.37574    0  288    0.64857    0.37574  42.1%     -  352s
         0     0    0.37574    0  314    0.64857    0.37574  42.1%     -  352s
         0     0    0.37598    0  294    0.64857    0.37598  42.0%     -  352s
         0     0    0.37598    0  239    0.64857    0.37598  42.0%     -  353s
         0     0    0.37599    0  259    0.64857    0.37599  42.0%     -  353s
         0     0    0.37599    0  319    0.64857    0.37599  42.0%     -  354s
         0     0    0.37599    0  312    0.64857    0.37599  42.0%     -  354s
         0     0    0.37599    0  310    0.64857    0.37599  42.0%     -  354s
         0     0    0.37604    0  317    0.64857    0.37604  42.0%     -  355s
         0     0    0.37624    0  252    0.64857    0.37624  42.0%     -  355s
         0     0    0.37628    0  284    0.64857    0.37628  42.0%     -  355s
         0     0    0.37647    0  311    0.64857    0.37647  42.0%     -  356s
         0     0    0.37659    0  316    0.64857    0.37659  41.9%     -  356s
         0     0    0.37663    0  343    0.64857    0.37663  41.9%     -  357s
         0     0    0.37668    0  345    0.64857    0.37668  41.9%     -  357s
         0     0    0.37717    0  318    0.64857    0.37717  41.8%     -  358s
         0     0    0.37717    0  326    0.64857    0.37717  41.8%     -  358s
         0     0    0.37731    0  285    0.64857    0.37731  41.8%     -  358s
         0     0    0.37731    0  330    0.64857    0.37731  41.8%     -  359s
         0     0    0.37741    0  358    0.64857    0.37741  41.8%     -  359s
         0     0    0.37748    0  357    0.64857    0.37748  41.8%     -  360s
         0     0    0.37748    0  368    0.64857    0.37748  41.8%     -  360s
         0     0    0.37761    0  363    0.64857    0.37761  41.8%     -  361s
         0     0    0.37761    0  339    0.64857    0.37761  41.8%     -  361s
         0     0    0.37761    0  376    0.64857    0.37761  41.8%     -  361s
         0     0    0.37761    0  379    0.64857    0.37761  41.8%     -  362s
    H    0     0                       0.5927748    0.37761  36.3%     -  362s
         0     0    0.37761    0  323    0.59277    0.37761  36.3%     -  363s
    H    0     0                       0.5496654    0.37761  31.3%     -  364s
         0     0    0.37778    0  292    0.54967    0.37778  31.3%     -  364s
         0     0    0.37778    0  291    0.54967    0.37778  31.3%     -  364s
         0     0    0.37778    0  311    0.54967    0.37778  31.3%     -  365s
         0     0    0.37778    0  361    0.54967    0.37778  31.3%     -  365s
         0     0    0.37778    0  271    0.54967    0.37778  31.3%     -  366s
         0     0    0.37778    0  271    0.54967    0.37778  31.3%     -  366s
    H    0     0                       0.5418974    0.37778  30.3%     -  370s
    H    0     0                       0.5406800    0.37778  30.1%     -  370s
         0     2    0.37778    0  271    0.54068    0.37778  30.1%     -  370s
        47    34 infeasible    6         0.54068    0.38315  29.1%  1195  375s
       109    86    0.42576    7  318    0.54068    0.38492  28.8%  1035  381s
       203   177    0.52836   11  220    0.54068    0.38492  28.8%   864  386s
       230   179 infeasible   11         0.54068    0.38492  28.8%   838  392s
    H  234   179                       0.5389522    0.38492  28.6%   835  392s
       240   181 infeasible   12         0.53895    0.38492  28.6%   851  395s
    H  252   181                       0.5324405    0.38492  27.7%   845  395s
       364   250    0.52836   18  272    0.53244    0.38492  27.7%   911  400s
       392   259 infeasible   20         0.53244    0.38796  27.1%   903  405s
       493   310 infeasible   55         0.53244    0.42005  21.1%   881  410s
       600   384    0.46651   92  112    0.53244    0.42005  21.1%   891  415s
       838   508    0.47263   13  239    0.53244    0.42426  20.3%   859  421s
       933   558    0.47263   17  239    0.53244    0.42426  20.3%   869  425s
      1056   666    0.47263   22  265    0.53244    0.42426  20.3%   907  430s
      1267   778    0.51024   13  215    0.53244    0.42643  19.9%   879  437s
      1429   869 infeasible   15         0.53244    0.42643  19.9%   871  440s
      1497   870    0.47263   15  271    0.53244    0.42643  19.9%   871  455s
      1506   876    0.51984   25  558    0.53244    0.42643  19.9%   866  463s
      1509   883    0.42643   11  416    0.53244    0.42643  19.9%  18.0  465s
      1553   900    0.42643   16  564    0.53244    0.42643  19.9%  48.2  470s
      1586   918    0.44554   18  273    0.53244    0.42643  19.9%  75.3  475s
      1602   929    0.44554   20  297    0.53244    0.42643  19.9%  90.6  481s
    H 1609   883                       0.5255392    0.42643  18.9%  93.8  481s
      1619   890 infeasible   19         0.52554    0.42643  18.9%   114  487s
      1631   893    0.44554   22  326    0.52554    0.42643  18.9%   138  491s
      1653   897    0.44554   24  304    0.52554    0.42643  18.9%   145  495s
      1682   907    0.44554   28  327    0.52554    0.42643  18.9%   153  502s
      1697   909    0.44554   30  306    0.52554    0.42643  18.9%   156  515s
      1706   915    0.44554   31  329    0.52554    0.42643  18.9%   158  520s
      1734   927    0.44554   36  341    0.52554    0.42643  18.9%   164  525s
      1775   929 infeasible   38         0.52554    0.42643  18.9%   175  530s
      1810   923    0.44765   42  500    0.52554    0.42643  18.9%   194  536s
      1825   925 infeasible   41         0.52554    0.42643  18.9%   203  541s

    Cutting planes:
      Gomory: 9
      Clique: 120
      MIR: 19
      StrongCG: 1
      Flow cover: 2
      GUB cover: 1
      Zero half: 4
      RLT: 11

    Explored 1867 nodes (1770273 simplex iterations) in 544.80 seconds (813.46 work units)
    Thread count was 16 (of 16 available processors)

    Solution count 9: 0.525539 0.532441 0.538952 ... 1

    Time limit reached
    Best objective 5.255391962461e-01, best bound 4.264330265154e-01, gap 18.8580%
    ---------------------------------------------------------------------------

    Multi-objectives: optimize objective 3  ...
    ---------------------------------------------------------------------------


    Loaded user MIP start with objective 1.50428e+06

    Presolve removed 111 rows and 1323 columns
    Presolve time: 0.71s
    Presolved: 8919 rows, 12544 columns, 296952 nonzeros
    Variable types: 2568 continuous, 9976 integer (9880 binary)
    Root relaxation presolved: 8777 rows, 12686 columns, 296468 nonzeros

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


    Root simplex log...

    Iteration    Objective       Primal Inf.    Dual Inf.      Time
           0    2.4482834e+04   8.219405e+04   7.363612e+10    546s

    Solved with dual simplex

    Root simplex log...

    Iteration    Objective       Primal Inf.    Dual Inf.      Time
        6863    1.0062257e+06   0.000000e+00   0.000000e+00    547s
    Extra simplex iterations after uncrush: 5

    Root relaxation: objective 1.006226e+06, 6863 iterations, 1.00 seconds (1.14 work units)

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

         0     0 1006225.67    0  462 1504280.83 1006225.67  33.1%     -  546s
    H    0     0                    1486968.4340 1006225.67  32.3%     -  548s
         0     0 1013066.20    0  617 1486968.43 1013066.20  31.9%     -  548s
         0     0 1013066.20    0  706 1486968.43 1013066.20  31.9%     -  548s
         0     0 1013066.20    0  713 1486968.43 1013066.20  31.9%     -  548s
         0     0 1015789.21    0  814 1486968.43 1015789.21  31.7%     -  550s
         0     0 1016155.77    0  823 1486968.43 1016155.77  31.7%     -  550s
         0     0 1018770.70    0  924 1486968.43 1018770.70  31.5%     -  551s
         0     0 1018770.70    0  551 1486968.43 1018770.70  31.5%     -  552s
    H    0     0                    1446572.8340 1018770.70  29.6%     -  553s
         0     2 1018770.70    0  524 1446572.83 1018770.70  29.6%     -  554s
        15    24 1018770.70    4  875 1446572.83 1018770.70  29.6%   483  555s
        39    42 1028866.23    6  824 1446572.83 1018770.70  29.6%   831  560s
    H   72    67                    1440802.0340 1018770.70  29.3%   959  563s
       101   100 1030857.57   15  811 1440802.03 1018770.70  29.3%   754  565s
    H  121   104                    1435031.2340 1018770.70  29.0%   659  569s
    H  129   110                    1388864.8340 1018770.70  26.6%   642  577s
       137   134 infeasible   18      1388864.83 1018770.70  26.6%   737  580s
       216   211 1043063.50   22  826 1388864.83 1018770.70  26.6%   568  590s
       246   228 infeasible   25      1388864.83 1018770.70  26.6%   677  595s
       312   292 infeasible   27      1388864.83 1018770.70  26.6%   683  600s

    Cutting planes:
      Gomory: 35
      Cover: 946
      Implied bound: 9
      Clique: 492
      MIR: 145
      StrongCG: 33
      GUB cover: 68
      Zero half: 23
      RLT: 21
      Relax-and-lift: 1

    Explored 422 nodes (240496 simplex iterations) in 604.83 seconds (899.60 work units)
    Thread count was 16 (of 16 available processors)

    Solution count 6: 1.38886e+06 1.43503e+06 1.4408e+06 ... 1.50428e+06

    Time limit reached
    Best objective 1.388864834000e+06, best bound 1.019533634000e+06, gap 26.5923%

    ---------------------------------------------------------------------------
    Multi-objectives: stopped in 604.92 seconds (899.60 work units), solution count 10
    Sub-optimal termination for some objective, not solved to optimality
    0

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