The NEOS Server offers Bonmin (**B**asic **O**pen-source
**N**onlinear **M**ixed **IN**teger programming) for the solution
of mixed-integer nonlinearly-constrained optimization problems. Bonmin is
also available open source under the Common Public License.
Problems for Bonmin can be submitted on the NEOS server in AMPL or GAMS
format.

Bonmin is an experimental open-source C++ code for solving general mixed-integer nonlinearly constrained problems. Bonmin features several algorithms

- B-BB is a NLP-based branch-and-bound algorithm,
- B-OA is an outer-approximation decomposition algorithm,
- B-QG is an implementation of Quesada and Grossmann's branch-and-cut algorithm,
- B-Hyb is a hybrid outer-approximation based branch-and-cut algorithm.

Bonmin is a hybrid between two classical algorithms for mixed-integer nonlinear programming: an outer-approximation-based branch-and-cut-based algorithm and a pure branch-and-bound algorithm. The user can set options to declare which version of the algorithm should be employed through NEOS.

Bonmin was developed by a large team of researchers at IBM and Carnegie Mellon:

- Pierre Bonami
- Lorenz Biegler
- Andrew Conn
- Gerard Cornuejols
- Ignacio Grossmann
- Carl Laird
- Jon Lee
- Andrea Lodi
- Francois Margot
- Nicolas Sawaya
- Andreas Wächter

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:

- It must be self contained, i.e., no $include or $batinclude statements.
- It may not execute external programs, i.e., no $call or execute statements.
- No file creation, i.e. no put files or $echo except for a file named 'results.txt'. Other files created in the GAMS model file will be deleted.

If you are unfamiliar with GAMS, the GAMS Documentation includes a GAMS Tutorial and User's Guide. 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.

Documentation for GAMS/CoinBonmin is available in PDF format.

Web Submission Form

You can submit an optimization problem specified in the GAMS modeling
language to be solved using the optimization tools on the NEOS Server.
You need to specify the absolute path to a GAMS file on your
system.

The Options file is optional and requires that the statement
exist before the solve
statement in your model file. At this time, only is supported; however, options may also be specified within the
model input file (see the GAMS documentation).

`<modelname>.optfile = 1 ;`

```
optfile =
1
```

Optional GDX file for inputs. This file will be renamed to in.gdx. The
model must include "$GDXIN in.gdx" to load this file.

The solver will return a compressed GDX file which contains all
symbols in the model.

The log file contains information generated by the algorithm
during a solve. Checking the box will cause the log file to be
included in the output returned.

Enter any additional comments here (e.g. to identify the data
for your own information). These comments will be returned
with your results.

E-Mail address: