Decision Optimization

Decision Optimization

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solving multiple small problems vs. one large problem

  • 1.  solving multiple small problems vs. one large problem

    Posted 09/04/13 09:35 PM

    Originally posted by: taidungman


    Hello everyone,

    Recently I did a simulation experiment for a particular LP. In each iteration I need to solve many instances. Say, Max(C_i*X_i| X_1 in A_i), where X_1 is a vector of decision variable and A1 is the feasible set for iteration i, i=1,...,n.

    Instead of solving n small problems, I can obtain the same results by solving a large combined problem

    Max(\sum_i C_i*X_i| X_i in A_i for i=1,...,n)

     

    Then, much to my surprise, I discovered that when "n" is not too large, it's quicker to solve the large problem instead of multiple small problems. Since I know little about how the algorithm in modern software packages actually works (by the way, I used MATLAB for the experiment), I'm wondering if anyone has any explanation for this? 

    I'm guessing the pre-processing steps (just like the idea of fixed costs) slows down the process of solving multiple problems, but I'm totally unsure. Thanks. 


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    #DecisionOptimization


  • 2.  Re: solving multiple small problems vs. one large problem

    Posted 09/09/13 01:31 PM

    Originally posted by: GGR


    Hi

     

    This forum is about constraint programming. For linear Programming issues please post on one of the forums in

     

    IBM ILOG >‎ IBM ILOG Optimization >‎ Mathematical Programming >‎

     

    Hope that helps

     


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  • 3.  Re: solving multiple small problems vs. one large problem

    Posted 09/10/13 10:17 AM

    Originally posted by: taidungman


    Thanks. Will do.


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    #DecisionOptimization