Jaromił Najman
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Latest activity by Jaromił Najman
Jaromił Najman commented,
Hello Abdalrahman, Do I understand correctly that you have a model where a binary variable \(u\) does not impact the optimal objective value but you would still like to have it set to \(1\) in the ...

Jaromił Najman commented,
You can model the following equivalent formulation \[\begin{align*}\min &\,\,z_1 \cdot z_2 \\z_1 & = f_{1}^{pwl}(x_1) \,\, (1)\\z_2 & = f_{2}^{pwl}(x_2) \,\, (2)\end{align*}\] You can use the addGe...

Jaromił Najman commented,
Hi Jan, Is there a special reason, why these bound propagations are not considered as Presolve? In my opinion, it is unnecessarily confusing to the user that sets Presolve=0. Presolve controls wh...

Jaromił Najman commented,
Hi Haoge, I saw in the documentation of the MIPFocus parameter that it only affects MIP problems. Will it also affect the MIQCP problem that I am solving? Yes, it will always affect quadratic mod...

Jaromił Najman commented,
Hi Haoge, I guess that sticking to the trial_911 formulation looks more promising. I cannot explain why the trial_919 formulation performs so much worse. I think that the best way to improve perfor...

Jaromił Najman commented,
Hi Jack, If you can automatically determine additional model knowledge which would result in fixing some binary variables (or tightening the formulation), you should always definitely add this info...

Jaromił Najman commented,
Hi Haoge, 1. I want to check how the BestBound is generated. Since my problem is a minimization problem, the Bestbound is the minimum (not the maximum) of all relaxations at the leaf nodes, right?...

Jaromił Najman commented,
Hi, The behavior you see makes sense. The reason is the constraint I have one quadratic constraint that restricts the continuous variables on a unit ball. which most likely introduces a lot of sy...

Jaromił Najman commented,
In addition to setting Method=2 and NodeMethod=2, you also have to set Crossover=0. This avoids the computation of a basis solution at the end of the root node which automatically leads to the usag...

Jaromił Najman commented,
Hi Jan, I double checked the behavior and what is happening is indeed expected. In any node (and also the root node), Gurobi performs trivial bound propagations irrespective of the Presolve setting...