Warm start of Gurobi

Ongoing

Jun Ling

• May 09, 2023 15:25

hello！

I use the warm start  of Gurobi when solving MILP problems.  I don't really understand what the output of the solution means. The following is the log of my optimization problem:

Optimize a model with 193613 rows, 219648 columns and 1727393 nonzeros
Model fingerprint: 0xb9d828e5
Variable types: 137280 continuous, 82368 integer (82368 binary)
Coefficient statistics:
  Matrix range     [1e-01, 1e+03]
  Objective range  [4e+00, 1e+05]
  Bounds range     [3e-02, 4e+02]
  RHS range        [3e-01, 5e+04]

User MIP start did not produce a new incumbent solution

Presolve removed 112027 rows and 113508 columns
Presolve time: 3.82s
Presolved: 81586 rows, 106140 columns, 488233 nonzeros
Variable types: 98753 continuous, 7387 integer (7387 binary)
Deterministic concurrent LP optimizer: primal and dual simplex
Showing first log only...
Root simplex log...
Iteration    Objective       Primal Inf.    Dual Inf.      Time
       0    2.0250830e+07   3.928851e+04   2.536149e+10      6s
   14855    5.2477739e+07   0.000000e+00   1.128216e+06      6s
Concurrent spin time: 0.01s
Solved with dual simplex
Root relaxation: objective 5.042488e+07, 53296 iterations, 3.65 seconds (3.38 work units)

Another try with MIP start

 

The following is my problem.

1. What does "User MIP start did not produce a new incumbent solution” mean?
2. What does "Another try with MIP start" mean? 
3. Why does "Another try with MIP start" appear after "user MIP startup does not produce new existing solution"? How can I understand that the initial point I gave did not produce a feasible solution, but the solution found another good feasible solution based on the information I gave?

 

Thanks in advance!

 

Related to

• MIPStart

0

• 

  David Torres Sanchez

  Gurobi Staff

  • May 09, 2023 21:07

  Hi Jiajie,
  
  Please see the following similar community post.
  
  Cheers, 
  David

  1
• 

  Jun Ling

  • May 10, 2023 02:55

  

  

  

  Hi，
  
  Thank you for the quick reply.  

  This Line

  Another try with MIP start
  

  Did Gurobi try again with MIP start based on the information I gave?

  Thanks in advance!

   

  0

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