Decision Optimization

Decision Optimization

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  • 1.  Which algorithm is used during cuts in the root node?

    Posted 09/30/11 11:03 AM

    Originally posted by: CPXfanatic


    I would like to know if the algorithm applied for the relaxations generated at root node is governed by parameter CPX_PARAM_STARTALG or CPX_PARAM_SUBALG in a MIP optimization. That is:
    Parallel mode: deterministic, using up to 4 threads.
Root relaxation solution time =    1.17 sec.                                    <--- STARTALG
 
        Nodes                                         Cuts/ 
   Node  Left     Objective  IInf  Best Integer     Best Node    ItCnt     Gap
 
      0     0       21.0428   205                     21.0428     2608
      0     0       21.7914   263                   Cuts: 222     3724
      0     0       22.3287   307                   Cuts: 102     5213
      0     0       22.4167   321                    Cuts: 98     5759
      0     0       22.5411   329                    Cuts: 60     7060
      0     0       22.6010   360                    Cuts: 54     8091          <--- ¿¿¿ Which one ???
      0     0       22.6274   369                    Cuts: 41     8890
      0     0       22.6457   366                    Cuts: 30     9527
      0     0       22.6694   387                    Cuts: 38    10466
      0     0       22.6906   366                    Cuts: 42    11277
      0     2       22.6906   366                     22.6906    11277
Elapsed real time =  16.61 sec. (tree size =  0.01 MB, solutions = 0)
      3     5       22.7140   283                     22.6931    12938
     13    15       22.7402   243                     22.6936    16662          <--- SUBALG
     27    29       22.7337   282                     22.6936    21306

    #CPLEXOptimizers
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  • 2.  Re: Which algorithm is used during cuts in the root node?

    Posted 09/30/11 01:36 PM

    Originally posted by: SystemAdmin


    It is the SUBALG. Basically, whenever there is a feasible starting basis at hand we use SUBALG. If not, we use STARTALG. Typically, the only time where there is no starting basis available is the initial root LP solve, so STARTALG is only used once.
    #CPLEXOptimizers
    #DecisionOptimization


  • 3.  Re: Which algorithm is used during cuts in the root node?

    Posted 09/30/11 01:53 PM

    Originally posted by: CPXfanatic


    Thanks!!
    #CPLEXOptimizers
    #DecisionOptimization


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