Model status 13: Error no solution, Solver status 10: Error: Solver Failure

[Merel]

Hi guys,

Could you please help me out.
I receive the following error/warning when running my MIP model in
AIMMS.

Warning: Model Status 13: Error no solution, Solver status 10: Error:
Solver failure (see message window).

Thanks in advance!!

Regards,
Merel

[Guido Diepen]

Hi Merel,

not sure which solver you are using to solve the MIP model. However, as stated in the error window there should be more specific information in the messages window as to why the solver had a problem.

You can open this messages window (which is different from the error window you normally see), either via the windows menu, or via the keyboard shortcut Ctrl-m. 

Guido Diepen

AIMMS Specialist

[Merel]

Hi Guido,

Thanks for the quick reply!
This is my first time working with AIMMS. I wasn´t aware of the
message window.
The error was the following:

There is 17.516 Mb in use.
Requested Memory Unavailable.
Requested Memory Unavailable.
XA tried to allocate 746.409 Mb of memory to load the model and
failed.
You could try to set the Solvers general option 'Solver workspace' to
a value smaller than 746.409 Mb (and higher than 0), and restart your
application.
See the AIMMS help for XA ('Troubleshooting') for more details.
Warning: Model status 13: Error no solution, Solver status 10: Error:
Solver failure.

In the help section it was suggested to in this case, change to CPLEX
11.2. So I did, and it indeed resolved the error and I could add some
additional parameters and variables to my model.

Unfortunately, now I receive the following error:

CPLEX error: Retrieving matrix failed. Not enough memory available.
Warning: Model status 13: Error no solution, Solver status 9: Error:
Setup failure.

I also tried to set the Solver workspace to a value smaller than
746.409 Mb (and higher than 0), unfortunately this had no impact.

Do you have any idea what I could do to resolve the above mentioned
error? I appreciate your help a lot!

Regards,
Merel

[Guido Diepen]

Hi Merel,

it could be that the model you are trying to solve is just too big for the memory you have in your computer. When the solver (XA or CPLEX) wants to request the memory to store the problem, it just gets the message that windows cannot provide that amount of memory.

If you open the progress windows (either via menu windows, or via Ctrl-p), how much memory is shown as still available?

If you have variables and constraints that are defined over multiple indices, you can see if you can limit the generated combinations by using domain conditions. Please see the AIMMS documentation and the AIMMS Blog (http://blog.aimms.com) for more information about domain conditions.

Guido Diepen

AIMMS Specialist

[Merel]

Hi Guido,

I managed to get access to a so-called 'super-computer' with more
memory, hoping this would solve my problem. Unfortunately, now I
receive the following error,

Memory allocation error: Out of memory error while trying to allocate
483844096 bytes from the system.

The message window shows the following,
There is 46.621 Mb in use.
Memory limit exceeded at line 1 in user-defined function section
"MainExecution", column 3.
Memory allocation error: Out of memory error while trying to allocate
870916096 bytes from the system.

Memory limit exceeded at line 1 in user-defined function section
"MainExecution", column 116.
Memory allocation error: Out of memory error while trying to allocate
580616192 bytes from the system.

Memory limit exceeded at line 1 in user-defined function section
"MainExecution", column 3.
Memory allocation error: Out of memory error while trying to allocate
483844096 bytes from the system.

Memory limit exceeded at line 1 in user-defined function section
"MainExecution", column 3.
Memory allocation error: Out of memory error while trying to allocate
483844096 bytes from the system.

Memory limit exceeded at line 1 in user-defined function section
"MainExecution", column 3.
Memory allocation error: Out of memory error while trying to allocate
483844096 bytes from the system.

The progress window indicates that 2865,3 mb memory is used and 4096,0
mb memory is free.

Could you help me out?

Kind regards,
Merel

[Guido Diepen]

Hi Merel,

I think you are running a 32 bit version of AIMMS on this supercomputer. Even though there might be lots of memory available, a 32 bit version of AIMMS will always be limited to maximally 4 GB.

Can you please ensure that you are using the 64 bit version of AIMMS to solve the problems on this supercomputer?

Guido Diepen

AIMMS Specialist

[Merel]

Hi Guido,

Thanks! The 64 bit version solved my problem!

Best regards,
Merel

[Merel]

Hi Guido,

I have another question.
I have parameters that are dependend on multiple indices (sets) and
thereby reflect different scenarios. I would like to assign
probabilities to these scenarios. How can I do so?

Kind regards,
Merel

[Guido Diepen]

Hi Merel,

if you want to work with some simple weighted cost or so, please take a look at our tutorial for professionals. In this tutorial we show how you can optimize the total weighted cost for three possible demand scenarios (pessimistic, expected, and optimistic) each with a given probability.

Or is your question related to the area of Stochastic Programming? In that case, please take a look at the examples about stochastic programming provided with the AIMMS installation.

Guido Diepen

AIMMS Specialist

[Merel]

Hi Guido,

The example in the professionals tutorial suits my purpose.
However, when running the model I receive the following error:

CPLEX: If you want to find out whether the problem is infeasible or
unbounded then try to run it with the CPLEX
option 'Presolve' set to 'no'.
Warning: After zero iterations the preprocessor of CPLEX 12.4
concluded that MaxNPV is infeasible or unbounded.
Warning: After 292 iterations CPLEX 12.4 concluded that an integer
solution to MaxNPV does not exist.

So what does this mean, are my constraints not strict enough?

Best regards,
Merel

[Guido Diepen]

Hi Merel,

this means exactly what it is stated :) 

Either your problem is infeasible, i.e. something like:

min x

s.t.

x + y >= 5

x + y <= 3

(this can never be satisfied at the same time)

Or your problem is unbounded:

min x

s.t. 

x <= 10

(This means that your problem is unbounded towards -infinity).

Please see the thread https://groups.google.com/d/topic/aimms/gRG1VLu6bRE/discussion for some more information about investigating the unbounded/infeasible question.

Guido Diepen

AIMMS Specialist