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NEOS Interfaces to Cbc

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Cbc

The COIN-OR Branch and Cut (Cbc) solver is an open-source mixed-integer linear programming solver written in C++. Problems for Cbc can be submitted on the NEOS server in AMPL, GAMS, or MPS format.

Cbc is intended to be used primarily as a callable library to create customized branch-and-cut solvers, however, a basic stand-alone executable is used to solve problems submitted to the NEOS Server. Cbc utilizes other COIN-OR projects Cgl (Cut Generation Library) to generate cutting planes and Cpl to solve the linear programs at each node of the tree.

Cbc was developed by John Forrest, now retired from IBM Research. The project is currently managed by John Forrest and Ted Ralphs. For more information on Cbc and the COIN-OR initiative, please visit the Cbc COIN-OR website.


Using the NEOS Server for Cbc/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 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.

Web Submission Form
Model File
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.
Options File
The Options file is optional and requires that the statement <modelname>.optfile = 1 ; exist before the solve statement in your model file. At this time, only optfile = 1 is supported; however, options may also be specified within the model input file (see the GAMS documentation).
GDX File
Optional GDX file for inputs. This file will be renamed to in.gdx. The model must include "$GDXIN in.gdx" to load this file.
Return GDX output
The solver will return a compressed GDX file which contains all symbols in the model.
Return log file
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.
Comments
Enter any additional comments here (e.g. to identify the data for your own information). These comments will be returned with your results.
Additional Settings
Dry run: generate job XML instead of submitting it to NEOS
Short Priority: submit to higher priority queue with maximum CPU time of 5 minutes
E-Mail address:
Please do not click the 'Submit to NEOS' button more than once.