source: stable/2.9/Cbc/README @ 2179

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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11(somehwat outdated) user's manual is available here: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   * Update for dependencies.
70
71 * Release 5.8.11
72
73   * Major overhaul of C interface
74   * Fixes to SOS
75   * Miscellaneous bug fixes
76
77 * Release 2.8.10
78
79   * More changes related to thread safety.
80   * Fix bug in build system with Visual Studio compiler.
81   * Miscellaneous bug fixes.
82
83 * Release 2.8.9
84
85   * Attempt to make Cbc thread safe.
86   * Add parallel examples.
87   * Add CbcSolverUsefulInfo.
88   * Bug fixes.
89
90 * Release 2.8.8
91
92   * Added example to show how to use Cbc with installed libraries in MSVC++
93   * Fixed inconsistency in addition of libCbcSolver to dependencies in
94     {{{cbc_addlibs.txt}}}.
95
96 * Release 2.8.7
97
98   * Changed so that Doxygen builds LaTex
99   * Fixes for build system
100
101 * Release 2.8.6
102
103   * Added option to explicitly link dependencies to comply with packaging
104     requirements on Fedora and Debian, as well as allow building of MinGW
105     DLLs.
106
107 * Release 2.8.5
108
109   * Minor fixes to build system
110
111 * Release 2.8.4
112   * Small bug fixes
113   * Upgrades to build system
114
115 * Release 2.8.3:
116
117   * Fix for handling SOS.
118
119 * Release 2.8.2:
120
121   * Fixed recognition of Glpk source in main configure.
122   * Minor bug fixes in CoinUtils, Clp, and Cbc.
123
124 * Release 2.8.1:
125
126   * Minor bug fixes
127
128 * Release 2.8.0:
129
130   * Introduced new secondaryStatus 8 to indicate that solving stopped due to
131     an iteration limit.
132   * Solution pool is now accessible via the command line and the CbcMain*
133     interface.
134   * New mipstart option to read an initial feasible solution from a file.
135     Only values for discrete variables need to be provided.
136
137   * Added Proximity Search heuristic by Fischetti and Monaci (off by
138     default): The simplest way to switch it on using stand-alone version is
139     ```-proximity on```.
140
141     Proximity Search is the new "No-Neighborhood Search" 0-1 MIP refinement
142     heuristic recently proposed by Fischetti and Monaci (2012). The idea is
143     to define a sub-MIP without additional constraints but with a modified
144     objective function intended to attract the search in the proximity of the
145     incumbent. The approach works well for 0-1 MIPs whose solution landscape
146     is not too irregular (meaning the there is reasonable probability of
147     finding an improved solution by flipping a small number of binary
148     variables), in particular when it is applied to the first heuristic
149     solutions found at the root node.
150   
151   * An implementation of Zero-Half-Cuts by Alberto Caprara is now available.
152     By default, these cuts are off. To use add to your command line
153     -zerohalfCuts root (or other options) or just -zero. So far, they may
154     help only on a small subset of problems and may need some tuning.
155
156     The implementation of these cuts is described in G. Andreello, A.
157     Caprara, and M. Fischetti "Embedding Cuts in a Branch and Cut Framework:
158     a Computational Study with {0,1/2}-Cuts" INFORMS Journal on Computing
159     19(2), 229-238, 2007 http://dx.doi.org/10.1287/ijoc.1050.0162
160
161   * An alternative implementation of a reduce and split cut generator by
162     Giacomo Nannicini is now available. By default, these cuts are off. To
163     use add to your command line -reduce2AndSplitCuts root (or other
164     options).
165
166     The implementation of these cuts is described in G. Cornuejols and G.
167     Nannicini "Practical strategies for generating rank-1 split cuts in
168     mixed-integer linear programming" Mathematical Programming Computation
169     3(4), 281-318, 2011 http://dx.doi.org/10.1007/s12532-011-0028-6
170
171   * An alternative robust implementation of a Gomory cut generator by Giacomo
172     Nannicini is now available. By default, these cuts are off. To use add to
173     your command line -GMI root (or other options).
174
175     The implementation of these cuts is described in G. Cornuejols, F.
176     Margot, and G. Nannicini "On the safety of Gomory cut generators"
177     http://faculty.sutd.edu.sg/~nannicini/index.php?page=publications
178
179   * To encourage the use of some of the more exotic/expensive cut generators
180     a parameter -slowcutpasses has been added. The idea is that the code does
181     these cuts just a few times - less than the more usual cuts. The default
182     is 10. The cut generators identified by "may be slow" at present are just
183     Lift and project and ReduceAndSplit (both versions).
184   
185   * Allow initialization of random seed by user. Pseudo-random numbers are
186     used in Cbc and Clp. In Clp they are used to break ties in degenerate
187     problems, while in Cbc heuristics such as the Feasibility Pump use them
188     to decide whether to round up or down. So if a different pseudo-random
189     seed is given to Clp then you may get a different continuous optimum and
190     so different cuts and heuristic solutions. This can be switched on by
191     setting randomSeed for Clp and/or randomCbcSeed for Cbc. The special
192     value of 0 tells code to use time of day for initial seed.
193   
194   * Building on this idea, Andrea Lodi, Matteo Fischetti, Michele Monaci,
195     Domenico Salvagnin, Yuji Shinano, and Andrea Tramontani suggest that this
196     idea be improved by running at the root node with multiple copies of
197     solver, each with its own different seed and then passing in the
198     solutions and cuts so that the main solver has a richer set of solutions
199     and possibly stronger cuts. This is switched on by setting
200     -multipleRootPasses. These can also be done in parallel.
201 
202   * Few changes to presolve for special variables and badly scaled problems
203     (in CoinUtils).
204
205   * New option -extraVariables <number> which switches on a trivial
206    re-formulation that introduces extra integer variables to group together
207    variables with same cost.
208
209   * For some problems, cut generators and general branching work better if
210     the problem would be infeasible if the cost is too high. If the new
211     option -constraintFromCutoff is set, the objective function is added as a
212     constraint which rhs is set to the current cutoff value (objective value
213     of best known solution).
214
215 * Release 2.7.8:
216
217   * Change message when LP simplex iteration limit is hit from "Exiting on
218     maximum nodes" to "Exiting on maximum number of iterations"
219   * Fix for using overlapping SOS.
220   * Fixes in buildsystem.
221
222 * Release 2.7.7:
223
224   * Fix to report interruption on user event if SIGINT is received by
225     CbcSolver. model->status() should now be 5 if this event happened. Added
226     method CbcModel::sayEventHappened() to make cbc stop due to an 'user
227     event'.
228
229   * Other minor fixes.
230
231 * Release 2.7.6:
232
233   * Fixes to build system.
234
235   * Other minor fixes.
236
237 * Release 2.7.5:
238
239   * Fixes to get AMPL interface working again.
240
241   * More fixes to MSVC++ files.
242
243 * Release 2.7.4:
244
245   * Minor bugfixes.
246
247 * Release 2.7.3:
248
249   * Minor bugfixes.
250
251   * Fixes to MSVC++ files.
252
253 * Release 2.7.2:
254
255   * Allow row/column names for GMPL models.
256
257   * Added CbcModel::haveMultiThreadSupport() to indicate whether Cbc library
258     has been compiled with multithread support.
259
260   * Added CbcModel::waitingForMiniBranchAndBound() to indicate whether
261     sub-MIP heuristic is currently running.
262
263   * Cbc shell should work with readline if configured with
264     ```--enable-gnu-packages```.
265
266   * Support for compressed input files (.gz, .bz2) is now enabled by default.
267
268   * Fix problems with relative gap tolerance > 100% and further bugs.
269
270   * Fixes for MSVC++ Version 9 files.
271
272   * Minor fixes in buildsystem; update to BuildTools 0.7.1.
273
274 * Release 2.7.1:
275
276   * Fixes to MSVC++ files
277
278 * Release 2.7.0:
279
280   * License has been changed to the EPL.
281
282   * Support for MSVC++ version 10 added.
283
284   * Support for BuildTools version 0.7 to incorporate recent enhancements,
285     including proper library versioning in Linux, prohibiting installation of
286     private headers, etc.
287
288   * Updated externals to new stable versions of dependent projects.
289
290   * Improvements to heuristics.
291
292   * New options for cut generation.
293
294   * Improved reporting of results.
295
296   * Improvements to documentation.
297
298   * Minor bug fixes.
299
300
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