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Strange behavior - Optimal solutions with different values, depend on whether StartSol is included

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7 comments

  • Jaromił Najman
    Gurobi Staff Gurobi Staff

    Hi Quan,

    Note that uploading files in the Community Forum is not possible but we discuss an alternative in Posting to the Community Forum.

    Best regards, 
    Jaromił

    0
  • Quan Hoang
    Gurobi-versary
    First Question
    First Comment

    Dear Jaromił,

    thank you for the instruction.

    Here is the Google Drive link to the two files I mentioned in the previous post. https://drive.google.com/drive/folders/1SqJGWgwyW8znC0RCoBkg6-nLHdhTl-G_?usp=sharing

    Hope it helps.

    Best regards,

    Quan.

    0
  • Jaromił Najman
    Gurobi Staff Gurobi Staff

    Hi Quan,

    Thank you for sharing the model and the solution file. I can reproduce the behavior and will investigate. I will update you on my findings.

    Best regards, 
    Jaromił

    0
  • Jaromił Najman
    Gurobi Staff Gurobi Staff

    Hi Quan,

    Thank you for reporting the issue.

    We have found the source of the issue and a fix will be available with the upcoming technical release.

    Best regards, 
    Jaromił

    0
  • Quan Hoang
    Gurobi-versary
    First Question
    First Comment

    Hi Jaromił,

    Thank you for updating me on the issue. I'll make sure to use the next release once it's available.

    In the meantime, is there any workaround to obtain the correct solution with the current Gurobi release (11.0.2)? I'm thinking of some (tricky) parameter settings but not entirely sure.

    Best regards,

    Quan.

    0
  • Jaromił Najman
    Gurobi Staff Gurobi Staff

    Hi Quan,

    Unfortunately, the only official parameter to currently avoid this issue is to set Presolve=0.

    Best regards, 
    Jaromił

    0
  • Quan Hoang
    Gurobi-versary
    First Question
    First Comment

    Thanks for letting me know. That is indeed unfortunate.

    0

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