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11(somehwat outdated) user's manual is available here: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