[Cbc] Fwd: CoinMP / CBC error

[Sean MacDermant]

CBC team:
Attached is the MPS file and below is a description of the issue.
CoinMP and CPLEX give very different results.
I know you are all probably heading to the INFORMS conference -- have a 
good conference!
Regards,
Sean


-------- Original Message --------
Subject:     CoinMP / CBC error
Date:     Fri, 12 Oct 2012 10:45:25 -0500
From:     Sean
To:     ted@

  I apologize for contacting you this way, but I tried to go on the CBC 
project page to log a ticket but upon trying to register I got the error 
at the bottom of this email from the TRAC system.  I did try.
Anyway, I use CoinMP, and I sent a problem to Bjarni Kristjansson and he 
suggested I send it to the CBC team as Maximal is convinced the problem 
lies in CBC.

Would you like me to send you the MPS file or to someone else?

Regards,
Sean



here is the email exchange on the problem:

Hi Sean,

Thanks for sending the model. We ran it with CPLEX and few other solvers 
and we come to the conclusion CoinMP is not returning the correct 
solution. The problem is most likely caused in CBC which is a mixed 
solver used by CoinMP. We will suggest that you report this to the 
project manager of CBC along with the MPS file.

Regards,

Farida Abou Draa


On Thu, Oct 11, 2012 at 10:50 AM, Sean MacDermant <seanmac> wrote:
Bjarni,
You must be finalizing plans for the INFORMS conference, but I
wanted to share this problem with you.

It is a problem where, when Using the 64-bit version of MPL,
you get different results for CPLEX from what you get with CoinMP.
This is a MIP with 968 BV variables.

All the default solver parameters were set for both.

I did notice a 'NONLINEAR' LINE that MPL put in the MPS file, right
before the BOUNDS section, but this is a linear MIP.

Can you tell what is going on?
Have a great time at INFORMS.


Regards,
Sean



CPLEX 12.3:




COIN MP 1.6:





  TRAC ERROR

==================================================


  Oops...

*Trac detected an internal error:*

IOError: [Errno 2] No such file or directory: ''

There was an internal error in Trac. It is recommended that you notify 
your local Trac administrator with the information needed to reproduce 
the issue.

To that end, you could a ticket.

The action that triggered the error was:

POST: /register

TracGuide <https://projects.coin-or.org/Cbc/wiki/TracGuide> --- The Trac 
User and Administration Guide




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