Xuan Lin

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Gurobi-versary
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  • Total activity 29
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Activity overview

Latest activity by Xuan Lin

  • Xuan Lin commented,

    1. Community
    2. Algorithms
    3. Nodes in MIP logging

    Hi Jaromił,   Thanks for the answer! The column It/Node shows the average number of Simplex iterations performed per node, i.e., the average number of Simplex iteration to solve a problem A to opt...

  • Xuan Lin created a post,

    Nodes in MIP logging

    Answered
    1. Community
    2. Algorithms

    Hi, I have a question regarding the explored nodes after reading the MIP Logging. I will start with my understanding of Branch and Bound: Initialize an empty list of relaxed problems L=[]. Put root...

    • Xuan Lin
    • Edited
    • 2 followers
    • 3 comments
    • 0 votes

  • Xuan Lin commented,

    1. Community
    2. Algorithms
    3. Problem with enlarging the model

    Hi Riley, Thanks for the answer! I think using simplex instead of concurrent solvers helps to reduce memory usage. I also managed to reduce the model size by improving the formulation. I have a mor...

  • Xuan Lin created a post,

    Problem with enlarging the model

    Answered
    1. Community
    2. Algorithms

    Hi, I am solving MILP models and trying to scale them up. When I try a smaller model like below, Gurobi quickly goes to the branch and bound procedure which solves the model very fast. I record one...

    • Xuan Lin
    • Edited
    • 2 followers
    • 3 comments
    • 0 votes

  • Xuan Lin commented,

    1. Community
    2. Programming
    3. Fast constraint rhs modification

    Hi Riley, Yes, what you said is correct, that is why the code I put here is a simplified model for debugging purposes. I have the complete model (~400 lines) that sets lb=ub to various nonzero valu...

  • Xuan Lin commented,

    1. Community
    2. Programming
    3. Fast constraint rhs modification

    Hi Riley, Thanks for the feedback and suggestions! I apologize for the complicated code, as I tried to keep the structure of the model to represent the original one. The x0_new[i_x] is always 0 - t...

  • Xuan Lin commented,

    1. Community
    2. Programming
    3. Fast constraint rhs modification

    Hi Riley, Does this work: https://drive.google.com/file/d/1vSNy0fVahVJsfrReZzjI9lfIXBEe7sUW/view?usp=sharing? I use the following code to read it into list of np.array: import csvfeas_cuts_offline ...

  • Xuan Lin commented,

    1. Community
    2. Programming
    3. Fast constraint rhs modification

    Hi Riley, My apologies for this super late reply. I have condensed my code but unfortunately, it still have ~150 lines. I use the x0=0 initial condition and run for 10 times. This code has 2 models...

  • Xuan Lin commented,

    1. Community
    2. Programming
    3. Fast constraint rhs modification

    Hi Riley, Could you confirm that I should submit the model through uploading port such as https://www.gurobi.com/upload-a-model/? Thank you! - Xuan

  • Xuan Lin commented,

    1. Community
    2. Programming
    3. Fast constraint rhs modification

    Hi Riley, I am unsure how many constraints lead to a highly constrained problem, but my model is relatively small (has like 20 binary variables, hence can solve fast) and has more than 700 constrai...