Dual infeasible due to empty column

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farzaneh.pourahmadi
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Dual infeasible due to empty column

Postby farzaneh.pourahmadi » 3 months ago

Hi,

I am trying to solve a model using CPLEX solver and I am getting "Dual infeasible due to empty column 'zu1'". Since I am sure that the model is correct, the column may be empty after presolve. How can I disable presolve setting to solve the problem?

Many thanks.







IBM ILOG CPLEX 24.1.3 r41464 Released Jul 26, 2013 WEI x86_64/MS Windows
--- GAMS/Cplex licensed for continuous and discrete problems.
Cplex 12.5.1.0

Reading data...
Starting Cplex...
Found incumbent of value 0.000000 after 0.08 sec. (25.34 ticks)
Dual infeasible due to empty column 'zu1'.
Presolve time = 1.16 sec. (318.28 ticks)

Root node processing (before b&c):
Real time = 1.25 sec. (355.12 ticks)
Sequential b&c:
Real time = 0.00 sec. (0.00 ticks)
------------
Total (root+branch&cut) = 1.25 sec. (355.12 ticks)
MIP status(118): integer unbounded
Cplex Time: 1.25sec (det. 355.12 ticks)
Problem is unbounded.
--- Restarting execution
--- dual2_linear2_slack_C&CG2.gms(426) 146 Mb
--- Reading solution for model dcopf73_s_1
--- Executing after solve: elapsed 0:02:30.712
--- dual2_linear2_slack_C&CG2.gms(409) 147 Mb
GDX2XLS 24.1.3 r41464 Released Jul 26, 2013 VS8 x86/MS Windows
Shell Execute 24.1.3 r41464 Released Jul 26, 2013 VS8 x86/MS Windows
The system cannot find the file specified
*** Status: Normal completion
--- Job dual2_linear2_slack_C&CG2.gms Stop 07/03/17 18:48:19 elapsed 0:02:31.753

cladelpino
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Re: Dual infeasible due to empty column

Postby cladelpino » 3 months ago

Hi, you have a real problem, not just an artifact generated by presolve. You can see that the primal problem is unbounded. This means the objective function can get "as low as possible" if minimizing or the opposite if maximizing.


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