RELAX4 solves linear minimum-cost flow problems and returns to the
user information about the optimization problem, the solution process,
and the solution.
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.
RELAX4 is a solver for minimum cost flow problems that combines the RELAX
code (see two papers by Bertsekas and Tseng (1988)) with an initialization
based on an auction/sequential shortest path algorithm. This initialization
is shown to be extremely helpful in speeding up the solution of difficult
problems, involving for example long augmenting paths, for which the
relaxation method has been known to be slow. On the other hand, this
initialization procedure does not significantly deteriorate the performance
of the relaxation method for the types of problems where it has been known
to be very fast.
The original RELAX4 solver for minimum-cost flow problems was written by
(Massachusetts Institute of Technology) and
Paul Tseng (University of Washington).
The RELAX4 code is publicly available via:
To use RELAX4 to solve a minimum-cost network flow problem, the user
must submit a problem in DIMACS standard format.