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Change solution strategy to standard (ImproveStartGap,ImproveStartNodes,ImproveStartTime)




  • Maliheh Aramon
    Gurobi Staff Gurobi Staff

    Hi Ilya, 

    The parameters ImproveStartGap, ImproveStartNodes, and ImproveStartTime trigger solution improvement strategies where the Gurobi Optimizer only focuses on improving the incumbent to find a better feasible solution and essentially gives up on improving the best bound. For example, with the setting ImproveStartTime = 500, the Gurobi Optimizer starts with the default setting and after 500 seconds, it then just focuses on improving the incumbent. 

    I guess you would like to start with a parameter setting that does focus on improving the best bound (MIPFocus=3, for example) and then after reaching a certain gap, node counts, and/or time, switch back to the default setting. To do so, you can start the optimization with setting MIPFocus=3 and check the gap, node count, and/or time in the MIP callback. You can then terminate the optimization in the callback as soon as reaching the specified limits, reset the parameters to their default values, and continue the optimization. Please check out our article on How do I change parameters in a callback?.

     Best regards,


  • Ilya Tyuryukanov
    First Comment
    First Question

    Thanks, this has worked. Very much appreciated.


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