does the timelimit parameter influences the quality of solution found by gurobi ?

lahlou aziz

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Nov 26, 2017, 11:58:33 AM11/26/17

to Gurobi Optimization

Hi,

I want to limit the timelimit parameter in Gurobi and I would like to know how much this parameter can limit and influences the quality of solutions found by gurobi in the lexicographical approach for multi objective optimization model where I have three functions.

I put a timelimit of 5*60 seconds and sometime for some inputs the Gap fields shows 0 all the time. What does this mean and how should one interpret it ?

Nodes | Current Node | Objective Bounds | Work

Expl Unexpl | Obj Depth IntInf | Incumbent BestBd Gap | It/Node Time

0 0 0.00000 0 40 - 0.00000 - - 3s

0 0 0.00000 0 72 - 0.00000 - - 4s

0 0 0.00000 0 56 - 0.00000 - - 5s

0 0 0.00000 0 56 - 0.00000 - - 6s

0 0 0.00000 0 64 - 0.00000 - - 6s

0 0 0.00000 0 40 - 0.00000 - - 7s

0 0 0.00000 0 40 - 0.00000 - - 8s

0 2 0.00000 0 40 - 0.00000 - - 295s

Could any one explain and clarify me how internally Gurobi works for such situations ? Knowing that I am preparing a paper to be submitted, how should I comment this part and give some clarifications ?

Regards,

Aziz

Daniel Espinoza

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Nov 30, 2017, 9:33:14 AM11/30/17

to Gurobi Optimization

Hi Aziz,

Time Limit is not a deterministic stopping criteria... it would depend on the load of your computer, so it might happen that for some times Gurobi will be able to finish... and sometimes it will not; this is independent of multiobjective optimization.

Now, the long delay between

```

0 0 0.00000 0 40 - 0.00000 - - 8s

0 2 0.00000 0 40 - 0.00000 - - 295s

```

Has to do with with processing the root node and deciding first branch decisions... that might take some times in some models

I hope that helps.

Best,

Daniel

lahlou aziz

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Nov 30, 2017, 2:03:03 PM11/30/17

to Gurobi Optimization

Hi Daniel,

I understand better now, thank you so much.

Regads,

Aziz

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