How to fix variables of the presolved model

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liu heng

2023年10月30日 07:13

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How to fix some variables of model m after m is presolved, and obtain a solution of the corresponding sub-MIP.

I tried to fix some variables of model p  = m.presolve() and solve it, however, p may introduces new variables and the mapping u: p →m is unaccessible so i can't obtain a solution of m.

 

関連

• Presolve

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  Silke Horn

  • Gurobi Staff

  2023年10月30日 07:23

  We do not recommend modifying the presolved model (since, as you noticed yourself, you cannot access the mapping back to the original model).

  Why can't you fix the variables in the original model?

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  liu heng

  2023年10月31日 02:52

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  Because I need to try many kinds of fixations and solve the sub-MIP, but i wish to presolve the original model m only once (to save time). In fact i don't need the mapping itself, i just need the solution of m, is there any method to achieve this?

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  Silke Horn

  • Gurobi Staff

  2023年11月09日 10:37

  This is not possible. You should fix the variables in the original model.

  How long does presolve take in your models?

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