Tobias Völk

• Total activity 17
• Last activity
• Member since
• Following 0 users
• Followed by 0 users
• Subscriptions 8

Activity overview

Latest activity by Tobias Völk
• Tobias Völk created a post,

Bug? Numerical Issue? Help! Optimal objective value of relaxation is negative despite being the sum of non-negative variables?

Awaiting user input

So I was using slack variables (indicating how much a constraint is violated for > 0, = 0 means that the constraint is fulfilled) to find any feasible solution as fast as possible (why doesn't Guro...

• Tobias Völk commented,

The alternative form is what I was looking for, thanks :)

• Tobias Völk created a post,

Change objective function during optimization

We cannot use a certain type of cut with Gurobi because it requires the replacement of a part of the objective function in the callback. It would be cool if there was some "on-your-own-risk"-way of...

• Tobias Völk created a post,

Query ruled out values for binary variables in callback

When Gurobi knows, that there is no feasible/optimal solution with (binary variable x_3) x_3 = 1, it would be cool if this could be queried during the callback. Not that Gurobi should try to look f...

• Tobias Völk created a post,

Proper way to access LP relaxation?

When Gurobi has solved a relaxation during it's Branch & Bound - Algorithm, I would like to look at the solution of the relaxation in order to add a type of cut which we found in a paper. What is t...

• Tobias Völk created a post,

Query which binary variables have known values during optimization in order to add additional constraints

If it doesn't exist yet, it would be a cool feature to have. Having binary variables x_1, x_2, ... Gurobi does rule out values for variables during optimization, right? For example, if it has deci...

• Tobias Völk created a post,

Indicator constraints with arbitrary right-hand-side (Python)

model.addGenConstrIndicator(...) As far as I can see (though that does not mean much of course), there is no reason why the right-hand-side has to be a float. Neither Math nor Python should pose a ...

• Tobias Völk created a post,