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1CBC README
2==========
3
4Welcome to the README for the COIN Branch and Cut Solver (CBC). CBC is
5distributed under the Eclipse Public License and is freely redistributable.
6All source code and documentation is Copyright IBM and others. This README may
7be redistributed freely.
8
9DOCUMENTATION
10=============
11
12For a quick start guide, please see the INSTALL file in this distribution. A (somehwat outdated) user's manual is available here:
13
14http://www.coin-or.org/Cbc
15
16More up-to-date automatically generated documentation of the source code can
17be found here:
18
19http://www.coin-or.org/Doxygen/Cbc/
20
21Further information can be found here:
22
23http://projects.coin-or.org/Cbc
24
25WHAT'S NEW
26==========
27
28Release 2.8:
29
301. Introduced new secondaryStatus 8 to indicate that solving stopped due to an iteration limit.
31
322. Solution pool is now accessible via the command line and the CbcMain* interface.
33
343. New mipstart option to read an initial feasible solution from a file. Only values for discrete
35   variables need to be provided.
36
374. Added Proximity Search heuristic by Fischetti and Monaci (off by default):
38   The simplest way to switch it on using stand-alone version is "-proximity on".
39
40   Proximity Search is the new "No-Neighborhood Search" 0-1 MIP refinement heuristic recently proposed by
41   Fischetti and Monaci (2012). The idea is to define a sub-MIP without additional constraints but with a
42   modified objective function intended to attract the search in the proximity of the incumbent. The approach
43   works well for 0-1 MIPs whose solution landscape is not too irregular (meaning the there is reasonable
44   probability of finding an improved solution by flipping a small number of binary variables), in particular
45   when it is applied to the first heuristic solutions found at the root node.
465. An implementation of Zero-Half-Cuts by Alberto Caprara is now available.
47   By default, these cuts are off.  To use add to your command line -zerohalfCuts root (or other options) or just -zero.
48   So far, they may help only on a small subset of problems and may need some tuning.
49
50   The implementation of these cuts is described in
51   G. Andreello, A. Caprara, M. Fischetti
52   â€œEmbedding Cuts in a Branch and Cut Framework: a Computational Study with {0,1/2}-Cuts”
53   INFORMS Journal on Computing 19(2), 229-238, 2007
546.  Allow initialization of random seed by user.  Pseudo-random numbers are used in Cbc and Clp.  In Clp they
55   are used to break ties in degenerate problems, while in Cbc heuristics such as the Feasibility Pump use them   
56   to decide whether to round up or down.  So if a different pseudo-random seed is given to Clp then you may get
57   a different continuous optimum and so different cuts and heuristic solutions. This can be switched on by
58   setting randomSeed for Clp and/or randomCbcSeed for Cbc.  The special value of 0 tells code to use time of day
59   for initial seed.
607.  Building on this idea Andrea Lodi , Matteo Fischetti , Michele Monaci , Domenico Salvagnin and Andrea Tramontani
61   suggest that this idea be be improved by running at the root node with multiple copies of solver, each
62   with its own different seed and then passing in the solutions and cuts so that the main solver has a richer
63   set of solutions and possibly stronger cuts.  This is switched on by setting multipleRootPasses.  These can also
64   be done in parallel.
65
66
67
68Release 2.7.8:
69   Look at https://projects.coin-or.org/Cbc/changeset?old_path=%2Freleases%2F2.7.7&new_path=%2Freleases%2F2.7.8 to see all changes.
70
711. Change message when LP simplex iteration limit is hit from "Exiting on maximum nodes"
72   to "Exiting on maximum number of iterations"
73
742. Fix for using overlapping SOS.
75
763. Fixes in buildsystem.
77
78Release 2.7.7:
79   Look at https://projects.coin-or.org/Cbc/changeset?old_path=%2Freleases%2F2.7.6&new_path=%2Freleases%2F2.7.7 to see all changes.
80
811. Fix to report interruption on user event if SIGINT is received by CbcSolver.
82   model->status() should now be 5 if this event happened.
83   Added method CbcModel::sayEventHappened() to make cbc stop due to an 'user event'.
84
852. Other minor fixes.
86
87Release 2.7.6:
88   Look at https://projects.coin-or.org/Cbc/changeset?old_path=%2Freleases%2F2.7.5&new_path=%2Freleases%2F2.7.6 to see all changes.
89
901. Fixes to build system.
91
922. Other minor fixes.
93
94Release 2.7.5:
95   Look at https://projects.coin-or.org/Cbc/changeset?old_path=%2Freleases%2F2.7.4&new_path=%2Freleases%2F2.7.5 to see all changes.
96
971. Fixes to get AMPL interface working again.
98
992. More fixes to MSVC++ files.
100
101Release 2.7.4:
102   Look at https://projects.coin-or.org/Cbc/changeset?old_path=%2Freleases%2F2.7.3&new_path=%2Freleases%2F2.7.4 to see all changes.
103
1041. Minor bugfixes.
105
106Release 2.7.3:
107   Look at https://projects.coin-or.org/Cbc/changeset?old_path=%2Freleases%2F2.7.2&new_path=%2Freleases%2F2.7.3 to see all changes.
108
1091. Minor bugfixes.
110
1112. Fixes to MSVC++ files.
112
113Release 2.7.2:
114   Look at https://projects.coin-or.org/Cbc/changeset?old_path=%2Freleases%2F2.7.1&new_path=%2Freleases%2F2.7.2 to see all changes.
115
1161. Allow row/column names for GMPL models.
117
1182. Added CbcModel::haveMultiThreadSupport() to indicate whether Cbc library has been compiled with multithread support.
119
1203. Added CbcModel::waitingForMiniBranchAndBound() to indicate whether sub-MIP heuristic is currently running.
121
1224. Cbc shell should work with readline if configured with --enable-gnu-packages.
123
1245. Support for compressed input files (.gz, .bz2) is now enabled by default.
125
1266. Fix problems with relative gap tolerance > 100% and further bugs.
127
1287. Fixes for MSVC++ Version 9 files.
129
1308. Minor fixes in buildsystem; update to BuildTools 0.7.1.
131
132Release 2.7.1:
133   Look at https://projects.coin-or.org/Cbc/changeset?old_path=%2Freleases%2F2.7.0&new_path=%2Freleases%2F2.7.1 to see all changes.
134
1351. Fixes to MSVC++ files
136
137Release 2.7.0:
138
1391. License has been changed to the EPL.
140
1412. Support for MSVC++ version 10 added.
142
1433. Support for BuildTools version 0.7 to incorporate recent enhancements,
144including proper library versioning in Linux, prohibiting installation of
145private headers, etc.
146
1474. Updated externals to new stable versions of dependent projects.
148
1495. Improvements to heuristics.
150
1516. New options for cut generation.
152
1537. Improved reporting of results.
154
1558. Improvements to documentation.
156
1579. Minor bug fixes.
158
159SUPPORT
160=======
161
1621. List Serve
163
164CBC users should use the Cbc mailing list. To subscribe, go to
165http://list.coin-or.org/mailman/listinfo/cbc
166
1673. Bug Reports
168
169Bug reports should be reported on the CBC development web site at
170
171https://projects.coin-or.org/Cbc/newticket
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