source: releases/2.9.8/README.md

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1# CBC Version 2.9.8 README
2
3Welcome to the README for the COIN Branch and Cut Solver (CBC). CBC is
4distributed under the Eclipse Public License and is freely redistributable.
5All source code and documentation is Copyright IBM and others. This README may
6be redistributed freely.
7
8## Current Testing Status
9
10[![Build Status](https://travis-ci.org/coin-or/Cbc.svg?branch=master)](https://travis-ci.org/coin-or/Cbc)
11
12[![Build status](https://ci.appveyor.com/api/projects/status/l2hwifsxwhswng8y/branch/master?svg=true)](https://ci.appveyor.com/project/tkralphs/cbc/branch/master)
13
14## DOCUMENTATION
15
16For a quick start guide, please see the INSTALL file in this distribution. A
17(somehwat outdated) user's manual is available here:
18
19http://www.coin-or.org/Cbc
20
21More up-to-date automatically generated documentation of the source code can
22be found here:
23
24http://www.coin-or.org/Doxygen/Cbc/
25
26Further information can be found here:
27
28http://projects.coin-or.org/Cbc
29
30## SUPPORT
31
32### List Serve
33
34CBC users should use the Cbc mailing list. To subscribe, go to
35http://list.coin-or.org/mailman/listinfo/cbc
36
37### Bug Reports
38
39Bug reports should be reported on the CBC development web site at
40
41https://projects.coin-or.org/Cbc/newticket
42
43## CHANGELOG
44
45 * Release 2.9.8
46
47   * Update to most current releases of dependencies
48   * Small bug fixes
49   * Add support for automatic build and test with Travis and Appveyor
50
51 * Release 2.9.7
52
53   * Small bug fixes
54   * Option to switch to line buffered output
55
56 * Release 2.9.6
57
58   * Small bug fixes
59
60 * Release 2.9.5
61
62   * Small bug fixes
63
64 * Release 2.9.4
65
66   * Small fixes for stability
67   * Fixes for Doygen documentation generation
68
69 * Release 2.9.3
70
71   * Minor bug fixes
72
73 * Release 2.9.2
74
75   * Fix for proper installation with ```DESTDIR```
76
77 * Release 2.9.1
78
79   * Fix for dependency linking
80   * Minor bug fixes
81
82 * Release 2.9.0
83
84   * Introduced specialized branching methods for dealing with "big Ms".
85   * Introduced new methods for dealing with symmetry (requires installation of [nauty](http://pallini.di.uniroma1.it/))
86   * Introduction of conflict cuts (off by default, turn on with `-constraint conflict`)
87
88 * Release 2.8.13
89
90   * Improved message handling
91   * Miscellaneous bug fixes.
92
93 * Release 2.8.12
94
95   * Update for dependencies.
96
97 * Release 2.8.11
98
99   * Major overhaul of C interface
100   * Fixes to SOS
101   * Miscellaneous bug fixes
102
103 * Release 2.8.10
104
105   * More changes related to thread safety.
106   * Fix bug in build system with Visual Studio compiler.
107   * Miscellaneous bug fixes.
108
109 * Release 2.8.9
110
111   * Attempt to make Cbc thread safe.
112   * Add parallel examples.
113   * Add CbcSolverUsefulInfo.
114   * Bug fixes.
115
116 * Release 2.8.8
117
118   * Added example to show how to use Cbc with installed libraries in MSVC++
119   * Fixed inconsistency in addition of libCbcSolver to dependencies in
120     {{{cbc_addlibs.txt}}}.
121
122 * Release 2.8.7
123
124   * Changed so that Doxygen builds LaTex
125   * Fixes for build system
126
127 * Release 2.8.6
128
129   * Added option to explicitly link dependencies to comply with packaging
130     requirements on Fedora and Debian, as well as allow building of MinGW
131     DLLs.
132
133 * Release 2.8.5
134
135   * Minor fixes to build system
136
137 * Release 2.8.4
138
139   * Small bug fixes
140   * Upgrades to build system
141
142 * Release 2.8.3:
143
144   * Fix for handling SOS.
145
146 * Release 2.8.2:
147
148   * Fixed recognition of Glpk source in main configure.
149   * Minor bug fixes in CoinUtils, Clp, and Cbc.
150
151 * Release 2.8.1:
152
153   * Minor bug fixes
154
155 * Release 2.8.0:
156
157   * Introduced new secondaryStatus 8 to indicate that solving stopped due to
158     an iteration limit.
159   * Solution pool is now accessible via the command line and the CbcMain*
160     interface.
161   * New mipstart option to read an initial feasible solution from a file.
162     Only values for discrete variables need to be provided.
163
164   * Added Proximity Search heuristic by Fischetti and Monaci (off by
165     default): The simplest way to switch it on using stand-alone version is
166     ```-proximity on```.
167
168     Proximity Search is the new "No-Neighborhood Search" 0-1 MIP refinement
169     heuristic recently proposed by Fischetti and Monaci (2012). The idea is
170     to define a sub-MIP without additional constraints but with a modified
171     objective function intended to attract the search in the proximity of the
172     incumbent. The approach works well for 0-1 MIPs whose solution landscape
173     is not too irregular (meaning the there is reasonable probability of
174     finding an improved solution by flipping a small number of binary
175     variables), in particular when it is applied to the first heuristic
176     solutions found at the root node.
177   
178   * An implementation of Zero-Half-Cuts by Alberto Caprara is now available.
179     By default, these cuts are off. To use add to your command line
180     -zerohalfCuts root (or other options) or just -zero. So far, they may
181     help only on a small subset of problems and may need some tuning.
182
183     The implementation of these cuts is described in G. Andreello, A.
184     Caprara, and M. Fischetti "Embedding Cuts in a Branch and Cut Framework:
185     a Computational Study with {0,1/2}-Cuts" INFORMS Journal on Computing
186     19(2), 229-238, 2007 http://dx.doi.org/10.1287/ijoc.1050.0162
187
188   * An alternative implementation of a reduce and split cut generator by
189     Giacomo Nannicini is now available. By default, these cuts are off. To
190     use add to your command line -reduce2AndSplitCuts root (or other
191     options).
192
193     The implementation of these cuts is described in G. Cornuejols and G.
194     Nannicini "Practical strategies for generating rank-1 split cuts in
195     mixed-integer linear programming" Mathematical Programming Computation
196     3(4), 281-318, 2011 http://dx.doi.org/10.1007/s12532-011-0028-6
197
198   * An alternative robust implementation of a Gomory cut generator by Giacomo
199     Nannicini is now available. By default, these cuts are off. To use add to
200     your command line -GMI root (or other options).
201
202     The implementation of these cuts is described in G. Cornuejols, F.
203     Margot, and G. Nannicini "On the safety of Gomory cut generators"
204     http://faculty.sutd.edu.sg/~nannicini/index.php?page=publications
205
206   * To encourage the use of some of the more exotic/expensive cut generators
207     a parameter -slowcutpasses has been added. The idea is that the code does
208     these cuts just a few times - less than the more usual cuts. The default
209     is 10. The cut generators identified by "may be slow" at present are just
210     Lift and project and ReduceAndSplit (both versions).
211   
212   * Allow initialization of random seed by user. Pseudo-random numbers are
213     used in Cbc and Clp. In Clp they are used to break ties in degenerate
214     problems, while in Cbc heuristics such as the Feasibility Pump use them
215     to decide whether to round up or down. So if a different pseudo-random
216     seed is given to Clp then you may get a different continuous optimum and
217     so different cuts and heuristic solutions. This can be switched on by
218     setting randomSeed for Clp and/or randomCbcSeed for Cbc. The special
219     value of 0 tells code to use time of day for initial seed.
220   
221   * Building on this idea, Andrea Lodi, Matteo Fischetti, Michele Monaci,
222     Domenico Salvagnin, Yuji Shinano, and Andrea Tramontani suggest that this
223     idea be improved by running at the root node with multiple copies of
224     solver, each with its own different seed and then passing in the
225     solutions and cuts so that the main solver has a richer set of solutions
226     and possibly stronger cuts. This is switched on by setting
227     -multipleRootPasses. These can also be done in parallel.
228 
229   * Few changes to presolve for special variables and badly scaled problems
230     (in CoinUtils).
231
232   * New option -extraVariables <number> which switches on a trivial
233    re-formulation that introduces extra integer variables to group together
234    variables with same cost.
235
236   * For some problems, cut generators and general branching work better if
237     the problem would be infeasible if the cost is too high. If the new
238     option -constraintFromCutoff is set, the objective function is added as a
239     constraint which rhs is set to the current cutoff value (objective value
240     of best known solution).
241
242 * Release 2.7.8:
243
244   * Change message when LP simplex iteration limit is hit from "Exiting on
245     maximum nodes" to "Exiting on maximum number of iterations"
246   * Fix for using overlapping SOS.
247   * Fixes in buildsystem.
248
249 * Release 2.7.7:
250
251   * Fix to report interruption on user event if SIGINT is received by
252     CbcSolver. model->status() should now be 5 if this event happened. Added
253     method CbcModel::sayEventHappened() to make cbc stop due to an 'user
254     event'.
255
256   * Other minor fixes.
257
258 * Release 2.7.6:
259
260   * Fixes to build system.
261
262   * Other minor fixes.
263
264 * Release 2.7.5:
265
266   * Fixes to get AMPL interface working again.
267
268   * More fixes to MSVC++ files.
269
270 * Release 2.7.4:
271
272   * Minor bugfixes.
273
274 * Release 2.7.3:
275
276   * Minor bugfixes.
277
278   * Fixes to MSVC++ files.
279
280 * Release 2.7.2:
281
282   * Allow row/column names for GMPL models.
283
284   * Added CbcModel::haveMultiThreadSupport() to indicate whether Cbc library
285     has been compiled with multithread support.
286
287   * Added CbcModel::waitingForMiniBranchAndBound() to indicate whether
288     sub-MIP heuristic is currently running.
289
290   * Cbc shell should work with readline if configured with
291     ```--enable-gnu-packages```.
292
293   * Support for compressed input files (.gz, .bz2) is now enabled by default.
294
295   * Fix problems with relative gap tolerance > 100% and further bugs.
296
297   * Fixes for MSVC++ Version 9 files.
298
299   * Minor fixes in buildsystem; update to BuildTools 0.7.1.
300
301 * Release 2.7.1:
302
303   * Fixes to MSVC++ files
304
305 * Release 2.7.0:
306
307   * License has been changed to the EPL.
308
309   * Support for MSVC++ version 10 added.
310
311   * Support for BuildTools version 0.7 to incorporate recent enhancements,
312     including proper library versioning in Linux, prohibiting installation of
313     private headers, etc.
314
315   * Updated externals to new stable versions of dependent projects.
316
317   * Improvements to heuristics.
318
319   * New options for cut generation.
320
321   * Improved reporting of results.
322
323   * Improvements to documentation.
324
325   * Minor bug fixes.
326
327
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