NEOS Server Home

NEOS Interfaces to RELAX4

WWW Form & Sample Submissions


RELAX4 solves linear minimum-cost flow problems and returns to the user information about the optimization problem, the solution process, and the solution. The original RELAX4 solver for minimum-cost flow problems was written by Dimitri Bertsekas (Massachusetts Institute of Technology) and Paul Tseng (University of Washington).

The RELAX4 code is publicly available via:

The NEOS Server interface to RELAX4 will accept inputs in either the DIMACS minimum-cost flow format or the RELAX4 format. The code can be used for any non-commercial research purposes and for comparative test purposes but cannot be used to satisfy commercial deliverables to government or industry without prior agreement with the authors.

Using the NEOS Server with RELAX4

To use RELAX4 to solve a minimum-cost network flow problem, the user must submit a problem in either the DIMACS standard format or the RELAX4 native format.

Web Submission Form
Enter the location of the RELAX4 input file
Enter the location of the DIMACS input file
Select the method for the initial solution. Relax-IV is the default initialization. The auction/shortest path subroutine, which is used for getting the initial price-flow pair, is recommended for difficult problems where the default initialization yields long solution times.
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.