Optimal solution

[Mauro Rozenberg]

Hi. I'm experimenting some difficulties with the result that Aimms is
returning.
I'm running a project that used to work perfectly but now returns an
optimal solution, such called by Aimms, while the Progess Window shows
me a LP Bound lower than the solution (I'm minimizing). It says GAP:
12,58%.
I've checked the Execution tolerances in the Aimms Option menu:
Equality absolute tolerance = 0
Equality relative tolerance = 1e-013
GUI non zero tolerance = 0

Thanks.
Mauro.

[Marcel Hunting]

Hi Mauro,

Is one of the options ‘Iteration Limit’, ‘Time Limit’, ‘Maximal Number
of Integer Solutions’ or ‘MIP Relative Optimality Tolerance’ (in the
category Solvers General) set to a non-default value? Also a solver
option limiting the number of nodes might be set. If one of these
options is set then the solver might terminate before finding the
optimal solution (and a gap of 0%).

The three options that you mentioned are not used by the solvers.

Best regards,

Marcel Hunting
AIMMS Software Developer

[Mauro Rozenberg]

Marcel,
Here's how the project is configurated:
Iteration time = 2147483647
Time limit = 30 (this is not why it finishes 'cos it says that te
solution is optimal)
Maximal number of integer solutions = 2100000000
MIP relative optimality tolerance = 1e-013
Maximal number of nodes (XA15) = 2100000000

Mauro.

[Mauro Rozenberg]

One more thing. I've checked the "Options with non default values"
menu. Here's whst it looks like:
Project title = Sugerencia de dotación
Warning duplicate column = Strict warning default
Warning duplicate row = Strict warning default
External procedure error handling = Raise warning when not checked
Intrinsic procedure error handling = Raise warning when not checked
Rounding compability = Aimms 3 7
Time limit = 30

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[Guido Diepen]

Hi Mauro,

from the description alone we cannot see what exactly is happening in
your case. If possible, I would like to ask you to send the project to
us via email ( sup...@aimms.com ). We can then take a detailed look
into what is causing the behavior.

Guido Diepen
AIMMS Specialist

[Mauro Rozenberg]

Guido,
I've sent the project with a case so that you can take a look at it.

Mauro.

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