The NEOS Server offers AlphaECP for the solution of mixed-integer nonlinear
optimization problems. Problems for AlphaECP can be submitted on NEOS
Server in GAMS format.
AlphaECP is based on the extended cutting plane (ECP) method, an extension
of Kelley's cutting plane method, which was originally given for convex NLP
problems. The method requires only the solution of a MIP subproblem in each
iteration. The MIP subproblems can be solved to optimality, to feasibility
or to only an integer-relaxed solution in intermediate iterations. This
makes the ECP algorithm efficient and easy to implement.
AlphaECP was developed by Tapio Westerlund and Toni Lastusilta of Abo
Akademi University in Finland.
For further information on AlphaECP and GAMS, please visit the AlphaECP/GAMS
The user must submit a model in GAMS
format to solve an optimization problem. For security purposes, the model
submitted must adhere to the following conventions:
If you are unfamiliar with GAMS, the
GAMS Documentation includes a
GAMS Tutorial and
Examples of models in GAMS format can be found in the
GAMS model library.
By default, the NEOS Server limits the amount of output generated in the listing
file by turning off the symbol and unique element list, symbol cross references,
and restricting the rows and columns listed to zero. This behavior can be changed
by specifying the appropriate options in the model file. See the
documentation on GAMS output
for further information.
You may optionally submit an options file if you wish to override the default parameter settings for the solver.
Currently, the NEOS Server can only use optfile=1 with GAMS input. Therefore, any model that specifies a different options file will not work as intended.
<modelname>.optfile = 1 ;
optfile = 1