Decision Optimization

 View Only
Expand all | Collapse all

CPLEX oplrun says the problem size has exceeded, but then proceeds to solve the problem anyway

  • 1.  CPLEX oplrun says the problem size has exceeded, but then proceeds to solve the problem anyway

    Posted Sun December 05, 2021 08:43 PM
    I have downloaded and installed the CPLEX Studio Community Edition 20.1.0.0 on my Linux machine (KUbuntu). I want to use the oplrun tool directly from the terminal. I can run it just fine. However, at the start of the program, it displays a message that says:

    IBM ILOG CPLEX Optimization Studio Community Edition. The CPLEX Optimizers will solve problems up to 1000 variables and 1000 constraints.
    Problem size limit exceeded.
    CP Optimizer Community Edition solves problems with search spaces up to 2^1000.
    Unrestricted version options (including academia) at https://ibm.co/2s0wqSa

    The message appears whatever input I use, and then, weirdly enough, it proceeds to solve the problem. I've tested with many different OPL examples at <install-dir>/opl/examples/opl. The above message in particular appeared when I used the input files at <install-dir>/opl/examples/opl/knapsack, which is a small example with just a few variables. So I have two questions:

    1. Why does this message appear?
    2. Why it proceeds to solve the problem if the problem is "supposedly" too large? Is the solution returned valid?

    ------------------------------
    Davi Pereira
    ------------------------------


  • 2.  RE: CPLEX oplrun says the problem size has exceeded, but then proceeds to solve the problem anyway

    Posted Mon December 06, 2021 10:39 AM

    Indeed even for models that are small enough like knapsack you get the message

    IBM ILOG CPLEX Optimization Studio Community Edition. The CPLEX Optimizers will solve problems up to 1000 variables and 1000 constraints. Problem size limit exceeded. CP Optimizer Community Edition solves problems with search spaces up to 2^1000. Unrestricted version options (including academia) at https://ibm.co/2s0wqSa

    but you should not see

    Problem size limit exceeded.

    That's a bug. But it is normal to be able to solve this with the FREE CPLEX community edition.



    ------------------------------
    [Alex] [Fleischer]
    [EMEA CPLEX Optimization Technical Sales]
    [IBM]
    ------------------------------