NEOS Interfaces to Couenne

Sample Submissions


The NEOS Server offers Couenne for the solution of mixed-integer nonlinearly-constrained (MINLP) and global optimization problems. Problems can be submitted to Couenne on the NEOS server in AMPL or GAMS format.

Couenne (Convex Over and Under ENvelopes for Nonlinear Estimation) is a branch-and-bound algorithm to solve mixed integer nonlinear programs (MINLPs) and global optimization problems. Couenne aims to find global optima of nonconvex MINLPs. It implements linearization, bound reduction, and branching methods within a branch-and-bound framework. Its main components are:

Additional details and options are available in the Couenne User's Manual.

Couenne was developed and is currently maintained by Pietro Belotti and others. More details on the solver are available on the Couenne page at COIN-OR.

Using the NEOS Server for Couenne/AMPL

The user must submit a model in AMPL format. Examples are provided in the examples section of the AMPL website.

The problem must be specified in a model file. A data file and commands files may also be provided. If the commands file is specified, it must contain the AMPL solve command; however, it must not contain the model or data commands. The model and data files are renamed internally by NEOS.

The commands file may include option settings for the solver. To specify solver options, add

  option couenne_options 'OPTIONS';
where OPTIONS is a list of one or more of the available solver options for AMPL.

Note: There is a minor bug in Couenne produces the message "infeasible solution" regardless of the solve outcome (e.g., even when a solution is found). Details can be found here.

Web Submission Form
Model File
Enter the location of the AMPL model
Data File
Enter the location of the AMPL data file
Commands File
Enter the location of the AMPL commands file
Options File
Enter the location of the couenne options file (local file)
Additional Settings

E-Mail address:
Please do not click the 'Submit to NEOS' button more than once.