[Help-glpk] glpk 4.24 release information

[Andrew Makhorin]

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GLPK 4.24 -- Release Information
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Release date: Nov 21, 2007

GLPK (GNU Linear Programming Kit) is intended for solving large-scale
linear programming (LP), mixed integer linear programming (MIP), and
other related problems. It is a set of routines written in ANSI C and
organized as a callable library.

In this release:

A tentative implementation of MIR (mixed integer rounding) cuts was
included in the MIP solver. To enable generating MIR cuts the control
parameter mir_cuts passed to the routine glp_intopt should be set to
GLP_ON. This feature is also available in the stand-alone solver glpsol
via command-line option '--mir'. For more details please see the
reference manual included in the distribution.

The implementation is mainly based on the following two papers:

1. H. Marchand and L. A. Wolsey. Aggregation and mixed integer rounding
   to solve MIPs. CORE Report 9839, CORE, Universite catholique de
   Louvain, June 1998.

2. G. Andreello, A. Caprara, and M. Fischetti. Embedding cuts in a
   Branch&Cut framework. Preliminary draft, October 2003.

MIR cuts can be generated on any level of the search tree that makes
the GLPK MIP solver to be a real branch-and-cut solver.

Using MIR cuts within the branch-and-cut solver allows solving some
hard MIP instances, which are absolutely intractable for an ordinary
branch-and-bound solver. (For example, the instances fiber, gesa2,
gesa2_o, gesa3, gesa3_o, pp08a, pp08acut from MIPLIB, which are known
to be hard, now can be solved by glpsol for less than a minute.)

A bug was fixed in the routine lpx_write_cpxlp. If a variable x has
upper bound and no lower bound, it should appear in the bounds section
as "-inf <= x <= u", not as "x <= u". Thanks to Enric Rodriguez
<address@hidden> for the bug report.

See GLPK web page at <http://www.gnu.org/software/glpk/glpk.html>.

GLPK distribution can be ftp'ed from <ftp://ftp.gnu.org/gnu/glpk/> or
from some mirror ftp sites; see <http://www.gnu.org/order/ftp.html>.

MD5 check-sum is the following:

765dcecc20dc6b80362e65c755f41976 *glpk-4.24.tar.gz

GLPK is also available as a Debian GNU/Linux package. See its web page
at <http://packages.debian.org/etch/glpk>.
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