Decision Optimization

Decision Optimization

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  • 1.  Can cplex solve nonconvex nonlinear programming?

    Posted 02/23/12 03:55 AM

    Originally posted by: adai


    I face a problem as nonconvex nonlinear programming problem.

    the objective function and all the other constraints is linear except the following inequation:

    -c~ij~ (x~i~-x~j~)^2^+-c~ij~a~i~a~j~(x~i~-x~j~)+c~ij~a~i~a~j~<=0, i,j=1,2,...M

    can this nonconvex nonlinear problem be solved by CPLEX?
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  • 2.  Re: Can cplex solve nonconvex nonlinear programming?

    Posted 02/27/12 05:21 PM

    Originally posted by: SystemAdmin


    No, CPLEX cannot solve non-convex problems with the exception of the integrality condition.

    But sometimes it is possible to model a non-convex MINLP as a MIP. For example, if all of your quadratic terms x*y contain at least one binary variable, say x, then you can model the term as
    
    x = 0 -> q = 0 x = 1 -> q = y
    

    and use q instead of x*y in your model. Note that the code above is using indicator constraints. CPLEX will automatically generate the corresponding big-M formulation, if it thinks that this is better. But of course you can model this with big-M yourself.
    Tobias
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