source: releases/2.9.6/README.md

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11(somehwat outdated) user's manual is available here: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