MCP Model Solve Aborted – 92 Errors During Execution (Beginner, Demo Version)

General
1

Hello everyone,

I am a beginner in GAMS and currently working with the demo version of GAMS (v53.5.1). I’m trying to run a CGE model (MCP formulation), and although my code compiles without syntax errors, the execution fails during the solve stage.

Here is the issue I’m facing:

  • The model compiles successfully.

  • During execution, GAMS starts generating the MCP model (BENIN_CGE_AFCFTA).

  • However, the solve is aborted with 92 errors.

Below is an extract of the key messages from the log:

--- Generating MCP model BENIN_CGE_AFCFTA
--- 96 rows 94 columns 876 non-zeroes
--- 2 fixed-and-unmatched column(s) will be treated as constant
...
92 Errors
*** SOLVE aborted
*** Status: Execution error(s)

Additional information:

  • Model type: MCP (Mixed Complementarity Problem)

  • GAMS version: 53.5.1 (Demo license)

  • System: Windows, 16 GB RAM

  • I am using the demo license, so I am aware there may be size or solver limitations.

I would really appreciate your guidance on the following:

  1. What could cause such a large number of errors during the solve phase but not at compilation?

  2. Could this issue be related to:

    • Model formulation (e.g., incorrect complementarity conditions, missing equations/variables)?

    • Scaling or numerical instability?

    • Limitations of the demo version?

  3. How can I effectively identify and debug these 92 errors in the .lst file?

Any advice, suggestions, or debugging strategies would be very helpful.
Thank you in advance for your support!

Best regards,

2

@SENOUMOD Potential errors in the definition of the MCP should be reported in the lst file, after the column listing. This can look for example as follows

**** Unmatched variable not free or fixed
     y(1,2,1)

**** Unmatched variable not free or fixed
     y(1,3,1)
[...]

If you are new to MCP, the following section of the documentation may be useful: Model and Solve Statements

I hope this helps!

Fred

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