Cutoff
Awaiting user input
Hello!
I am working on a problem related to minimizing the number of edges in a network that need to be turned off for the flow of a network to be 0.
I know that turning certain edges off should be 0 but Gurobi does not find the solution; I would expect it to raise an infeasible flag. Instead, I receive a cutoff flag because I am limiting the number of nodes to one.
My question goes more into how I can debug the modeling not finding the correct solution.
When I try to compute the IIS, it tells me the model is feasible.
-
You can fix the variables to the solution values if you know a specific solution. To do this, set the variable's lower and upper bound to its value in the known solution.
If the resulting model is infeasible, you can use computeIIS.I know that turning certain edges off should be 0 but Gurobi does not find the solution; I would expect it to raise an infeasible flag. Instead, I receive a cutoff flag because I am limiting the number of nodes to one.
I am not sure what you mean by this. Could you give more details? Do you use a callback function?
0 -
Hey Marika! Thank you very much for your response.
What I meant is that I am using the cutoff parameter:
https://www.gurobi.com/documentation/9.5/refman/cutoff.html
Otherwise when I fix the value of that variable, the problem gives me that 2 nodes should be turned off when in reality only one should be off.0 -
Ok, but I still think you should try to force the solution you have in mind to see why it is not possible or found.
Couldn't you fix the flow to 0, only allow one node to be turned off, and then check why this is not valid?0
Please sign in to leave a comment.
Comments
3 comments