The NEOS Server offers
(Extended Mathematical Programming), an (experimental) framework for
automated mathematical programming reformulations through the solver
Models that cannot be solved reliably are reformulated into models of
established mathematical programming classes in order to use advanced
EMP supports the modeling of Bilevel Programs, Variational Inequalities,
Disjunctive Programs, Extended Nonlinear Programs and Embedded
Complementarity Systems. The reformulation is done by the solver JAMS,
which is currently the only solver that is capable of handling EMP
The GAMS EMP Library, which is included in the GAMS Distribution, includes
examples demonstrating how to use the EMP framework and the solver JAMS.
JAMS is included free of charge with any licensed GAMS system but needs a
subsolver to solve the generated models. Additional information on EMP can be
EMP has been developed jointly by
Michael Ferris of UW-Madison,
of Carnegie Mellon University, and GAMS Development Corporation.
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