Lorenz Wagner
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Recent activity by Lorenz Wagner-
Solve scheduling model using a greedy heurisitc
AnsweredI have the following scheduling problem. Relatively simple and not very complex (only serves as an example). The indexes are \(I\) worker, \(T\) days and \(J\) shift. The decision variable is \(x_{...
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Technical questions regarding binary variables
AnsweredHello, I have a purely technical question about Gurobi. Suppose I have the variable \(y_{ijk} \in [0;1]\) . Now I want to define a binary variable \(x_{ijk}\) that takes the value 1 if \(y_{ijk}=1...
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Weird incumbent behavior
AnsweredHello, I have the following problem. I am trying to evaluate the lowe bound and the incumbent via the log of my model and use the glt.get_dataframe() command to create a DataFrame. Unfortunately I ...
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How to implement an optimality gap plot?
AnsweredHi, I came across this plot earlier and was wondering what exactly it says and how to implement it with Gurobi?I think with a callback function (as seen here), but I don't know which values I have ...
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Deal with quadratic constraints
OngoingHello, I have the following problem. I am setting up a linear programme (or so I thought), but my model output shows something like this. Model has xxxx quadratic constraints Is there any way I can...
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Help with implementing an LP
OngoingHello folks, I need your help. I'm currently trying to implement an old LP (which I set up as part of my research at university) in a new programming language for nostalgic reasons. The old model w...
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Help implementing a weird model notation
AnsweredHey guys, I recently came across this model notation and I am having a hard time understanding and implementing it in Gurobi. [\\sum_{i,t:i.GG=1\wedge i.O=b}^{}x_{jit}\ge5 \forall j,b\] How do I "...
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MILP Model Comparison
Awaiting user inputHello, I have a question. I am currently setting up two shift schedule optimization models. One of them constrains the number of worker shift changes using the 'changes' parameter. In the second mo...
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Complete different solution for nearly identical paramters
AnsweredHello, I have the following question. I have a model ("m") for planning shifts and in it a parameter that I can vary. Now, even if I change this now marginally, then completely different plans come...
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Save runtime in a list
AnsweredHi, I would like to run my model through different loops, always storing the runtime of each pass in a list. I have managed to do this, but there are two things I would like to adjust to make it mo...