Decision Optimization

Decision Optimization

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  • 1.  Setting MIP start effort level for all solutions in solution pool

    Posted 03/28/12 12:38 AM

    Originally posted by: Washout


    I am using the Java api for CPLEX 12.3 and I first solve my MIP, and have a number of solutions, the best of which is the incumbent. I then add some extra constraints and try to solve the new (modified) model using the previous solutions.

    I dont explicitly write the solutions to a .mst or .sol file - but the solutions are there in memory as the program is still running.

    Currently, when solving the new problem, the solver has an effort level of 4 on the best previous solution, and level 1 effort (which just checks feasibility, doesnt attempt to repair) on all the other solutions. How to I have the solver make a "level 4" effort on ALL of the solutions in the solution pool?
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  • 2.  Re: Setting MIP start effort level for all solutions in solution pool

    Posted 03/28/12 01:38 AM

    Originally posted by: Washout


    ...to clarify - adding the extra constraints could potentially render previously feasible solutions , infeasible under the new constraints
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  • 3.  Re: Setting MIP start effort level for all solutions in solution pool

    Posted 03/28/12 04:01 AM

    Originally posted by: SystemAdmin


    Is IloCplex.changeMIPStart(int mipstartindex, IloCplex.MIPStartEffort effort) what you are looking for (see also the reference documentation here).
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  • 4.  Re: Setting MIP start effort level for all solutions in solution pool

    Posted 03/29/12 05:51 PM

    Originally posted by: Washout


    Hi Daniel,

    Thanks for your reply - I was able to iterate through each of the solutions in my solution pool (I skipped the first solution as it is the incumbent) and set the effort level to repair. But then when I call the solve() method again it simply only tries to repair the incumbent solution only. Am I doing something wrong here?
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  • 5.  Re: Setting MIP start effort level for all solutions in solution pool

    Posted 03/30/12 06:46 AM

    Originally posted by: SystemAdmin


    Hm, could you please attach the full log output here? That would make it a little easier to figure out what is going on.
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  • 6.  Re: Setting MIP start effort level for all solutions in solution pool

    Posted 04/01/12 10:14 PM

    Originally posted by: Washout


    My error was in adding the constraints before changing the MIPStartEffort level it seems. When I changed the effort levels before adding the additional constraints it seems to work fine. Thanks for your reply.
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