Provide Variable Hints from AMPL

John Cox

• June 26, 2020 13:34

I have a MIQCP defined as an AMPL model. I would like to provide the solver variable hints to see if solution times can be improved. These hints are developed using a MIP relaxation of the same model.

I have tried the following in AMPL (as well as other variations on the suffix name like hintval, hint, etc.)

suffix varhintval IN;

let y[1].varhintval := 1;

...

The solver seems to be ignoring these suffixes as there is no change in the log output with or without them. If there is not a straightforward way to provide these from AMPL, I'm open to switching to the Python API but would prefer to avoid rewriting the problem if at all possible.

Any advice is greatly appreciated!

I'd also be curious how to query the Kappa value from the solver from AMPL, to check the numeric quality of the solution. I've seen examples of how to query this value from the other Gurobi APIs, but nothing on AMPL.

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• Official comment

  

  Simranjit Kaur

  Gurobi Staff

  • December 06, 2024 00:44

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