• Gurobi Staff

Hi Bobak,

There is a detailed section named Logging in Gurobi Reference Manual that explains the information contained in the log in detail. You should be able to find the answers to your questions in:

Please have a look at the sections referenced above and then let us know of any remaining questions you might have.

Best regards,

Maliheh

Hi Maliheh,

Thank you for the response. The links cleared up most things. I still however have one question. In the "Objective Bounds" section in the second image, does the incumbent value represent the value of the best feasible solution to the original MIP obtained? Or does it means the objective value of a relaxation of the original MIP that has been obtained? Furthermore, does any node in the region the branch-and-cut algorithm has cut the solution space down to have an objective value between the Incumbent and Best Bound values?

Thank you!

• Gurobi Staff

Hi Bobak,

The incumbent is the best feasible solution found so far for the original MIP problem. In a minimization problem, the incumbent and the best bound at any time during the search represent, in respective terms, the upper bound and the lower bound on the optimal objective value. For example, if the incumbent is $$y$$ and the best bound is $$x$$, this implies that the optimal objective value cannot be greater than $$y$$ and cannot be lower than $$x$$.

Best regards,

Maliheh

Thank you Maliheh! I have one further question. In the output of the second image, we see that there is sometimes an H on the left-hand side. From the links you sent me, I gather that means a heuristic was applied in that step. Is it possible to program it so that Gurobi tells me what heuristic it used? It could be quite helpful.

Thanks,

Bobak

Hi Maliheh,

I don't know if you saw my latest question, but if you could answer it that would be very helpful! Thanks :)

-Bobak

• Gurobi Staff

Hi  Bobak,

Sorry, I missed this.

No, Gurobi does not provide information in the log on which heuristic is used with one exception. If you set the parameter NoRelHeurTime to a non-zero value, the Gurobi Optimizer utilizes a heuristic named NoRel (no relaxation) before solving the root node. This heuristic is effective in finding high-quality feasible solutions especially on large MIPs where the root relaxation is computationally expensive.

Best regards,

Maliheh