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cplex save cplex mip and continue later

  • 12 June 2019
  • 4 replies
  • 217 views

Userlevel 1
Hi,

Is it possible to stop a cplex milp solver, save to disk and resume later?
How to do that?

Thanks!


EDIT:
Does this work...
  1. Start cplex milp solver and wait for incumbent solution
  2. Save a case file with an incumbent solution to a case file.
  3. Restart AIMMS, open model and load case file.
  4. Set Advanced start -> Use advanced basis.
  5. Start cplex milp solver again.
Is there another method?
Is this similar to just letting the solver continue?
Is it possible to save and load the tree? Is that required?

Thanks.
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Best answer by Marcel Hunting 17 June 2019, 12:25

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4 replies

Userlevel 4
Badge +1
The steps you described will work, but from what my understanding, it is a new solve, so the previous information of the tree or cut is not stored. I do not know other possibilities.
Userlevel 1
OK, thanks.
Maybe the CPLEX user community has an answer to this. I will search there.
Userlevel 4
Badge +1
AIMMS can only continue a CPLEX solve in the same AIMMS session, so not if you restart AIMMS. (To be precise, the CPLEX solve can only be continued if the corresponding generated math program in AIMMS is not deleted.)

Continuing a CPLEX solve after restarting AIMMS would require that you can save and load the branch-and-bound tree in/from a file but CPLEX no longer offers that functionality (old versions of CPLEX did support the .tre file).

With the Advanced Start option you can pass the incumbent solution as a MIP start to CPLEX, but the effect of using a MIP start is usually limited.
Userlevel 1
OK, clear now. Thanks for your answer.

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