What methods does Gurobi use to find the optimal solution of the vehicle routing problem?

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Vuttimate Rungseekulawat

2022年04月06日 17:52

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Hello everyone, I am a 4th year student and I'm working on a project and writing code to solve problems about ‘Inventory Routing Problem’

 

I have tried the command "print(m.getParamInfo('Method'))"

 

As a result, it got (-1), which means "automatic".

 

So I'm wondering what is this automatic method? Is it "branch and bound" since my model is MIP or not?

 

Best regards

Vuttimate

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  Simranjit Kaur

  • Gurobi Staff

  2025年11月16日 23:40

  This post is more than three years old. Some information may not be up to date. For current information, please check the Gurobi Documentation or Knowledge Base. If you need more help, please create a new post in the community forum, or try Gurobot, our chatbot interface offering instant, expert-level support.
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  Maliheh Aramon

  • Gurobi Staff

  2022年04月07日 02:44

  Hi Vuttimate, 

  The parameter Method indicates the algorithm used to solve the initial root relaxation of your MIP model. According to the documentation, the default automatic setting (value of -1) for a MIP means:

  In the current release, the default Automatic (-1) setting will typically choose ..., and dual (Method=1) for the MIP root relaxation. If the size of the MIP root relaxation is large, then it will often select deterministic concurrent (Method=4) or deterministic concurrent simplex (Method=5).

  The log shows that your model is a MIP and the Gurobi Optimizer solves it using a linear-programming based branch-and-bound algorithm. To check whether your model is a MIP or not, you can query the value of the model attribute IsMIP. If the value is 1, it means that the model is a MIP.

  Best regards,

  Maliheh

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  Vuttimate Rungseekulawat

  2022年04月08日 08:52

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  Hi Maliheh,

  Thank you so much for your response. 

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