source: stable/2.9/Cbc/README @ 2160

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1# CBC Version 2.9.3 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11(somehwat outdated) user's manual is available here: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 2.9.3
40
41   * Minor bug fixes
42
43 * Release 2.9.2
44
45   * Fix for proper installation with ```DESTDIR```
46
47 * Release 2.9.1
48
49   * Fix for dependency linking
50   * Minor bug fixes
51
52 * Release 2.9.0
53
54   * Introduced specialized branching methods for dealing with "big Ms".
55   * Introduced new methods for dealing with symmetry (requires installation of [nauty](http://pallini.di.uniroma1.it/))
56   * Introduction of conflict cuts (off by default, turn on with `-constraint conflict`)
57
58 * Release 2.8.13
59
60   * Improved message handling
61   * Miscellaneous bug fixes.
62
63 * Release 2.8.12
64   * Update for dependencies.
65
66 * Release 5.8.11
67
68   * Major overhaul of C interface
69   * Fixes to SOS
70   * Miscellaneous bug fixes
71
72 * Release 2.8.10
73
74   * More changes related to thread safety.
75   * Fix bug in build system with Visual Studio compiler.
76   * Miscellaneous bug fixes.
77
78 * Release 2.8.9
79
80   * Attempt to make Cbc thread safe.
81   * Add parallel examples.
82   * Add CbcSolverUsefulInfo.
83   * Bug fixes.
84
85 * Release 2.8.8
86
87   * Added example to show how to use Cbc with installed libraries in MSVC++
88   * Fixed inconsistency in addition of libCbcSolver to dependencies in
89     {{{cbc_addlibs.txt}}}.
90
91 * Release 2.8.7
92
93   * Changed so that Doxygen builds LaTex
94   * Fixes for build system
95
96 * Release 2.8.6
97
98   * Added option to explicitly link dependencies to comply with packaging
99     requirements on Fedora and Debian, as well as allow building of MinGW
100     DLLs.
101
102 * Release 2.8.5
103
104   * Minor fixes to build system
105
106 * Release 2.8.4
107   * Small bug fixes
108   * Upgrades to build system
109
110 * Release 2.8.3:
111
112   * Fix for handling SOS.
113
114 * Release 2.8.2:
115
116   * Fixed recognition of Glpk source in main configure.
117   * Minor bug fixes in CoinUtils, Clp, and Cbc.
118
119 * Release 2.8.1:
120
121   * Minor bug fixes
122
123 * Release 2.8.0:
124
125   * Introduced new secondaryStatus 8 to indicate that solving stopped due to
126     an iteration limit.
127   * Solution pool is now accessible via the command line and the CbcMain*
128     interface.
129   * New mipstart option to read an initial feasible solution from a file.
130     Only values for discrete variables need to be provided.
131
132   * Added Proximity Search heuristic by Fischetti and Monaci (off by
133     default): The simplest way to switch it on using stand-alone version is
134     ```-proximity on```.
135
136     Proximity Search is the new "No-Neighborhood Search" 0-1 MIP refinement
137     heuristic recently proposed by Fischetti and Monaci (2012). The idea is
138     to define a sub-MIP without additional constraints but with a modified
139     objective function intended to attract the search in the proximity of the
140     incumbent. The approach works well for 0-1 MIPs whose solution landscape
141     is not too irregular (meaning the there is reasonable probability of
142     finding an improved solution by flipping a small number of binary
143     variables), in particular when it is applied to the first heuristic
144     solutions found at the root node.
145   
146   * An implementation of Zero-Half-Cuts by Alberto Caprara is now available.
147     By default, these cuts are off. To use add to your command line
148     -zerohalfCuts root (or other options) or just -zero. So far, they may
149     help only on a small subset of problems and may need some tuning.
150
151     The implementation of these cuts is described in G. Andreello, A.
152     Caprara, and M. Fischetti "Embedding Cuts in a Branch and Cut Framework:
153     a Computational Study with {0,1/2}-Cuts" INFORMS Journal on Computing
154     19(2), 229-238, 2007 http://dx.doi.org/10.1287/ijoc.1050.0162
155
156   * An alternative implementation of a reduce and split cut generator by
157     Giacomo Nannicini is now available. By default, these cuts are off. To
158     use add to your command line -reduce2AndSplitCuts root (or other
159     options).
160
161     The implementation of these cuts is described in G. Cornuejols and G.
162     Nannicini "Practical strategies for generating rank-1 split cuts in
163     mixed-integer linear programming" Mathematical Programming Computation
164     3(4), 281-318, 2011 http://dx.doi.org/10.1007/s12532-011-0028-6
165
166   * An alternative robust implementation of a Gomory cut generator by Giacomo
167     Nannicini is now available. By default, these cuts are off. To use add to
168     your command line -GMI root (or other options).
169
170     The implementation of these cuts is described in G. Cornuejols, F.
171     Margot, and G. Nannicini "On the safety of Gomory cut generators"
172     http://faculty.sutd.edu.sg/~nannicini/index.php?page=publications
173
174   * To encourage the use of some of the more exotic/expensive cut generators
175     a parameter -slowcutpasses has been added. The idea is that the code does
176     these cuts just a few times - less than the more usual cuts. The default
177     is 10. The cut generators identified by "may be slow" at present are just
178     Lift and project and ReduceAndSplit (both versions).
179   
180   * Allow initialization of random seed by user. Pseudo-random numbers are
181     used in Cbc and Clp. In Clp they are used to break ties in degenerate
182     problems, while in Cbc heuristics such as the Feasibility Pump use them
183     to decide whether to round up or down. So if a different pseudo-random
184     seed is given to Clp then you may get a different continuous optimum and
185     so different cuts and heuristic solutions. This can be switched on by
186     setting randomSeed for Clp and/or randomCbcSeed for Cbc. The special
187     value of 0 tells code to use time of day for initial seed.
188   
189   * Building on this idea, Andrea Lodi, Matteo Fischetti, Michele Monaci,
190     Domenico Salvagnin, Yuji Shinano, and Andrea Tramontani suggest that this
191     idea be improved by running at the root node with multiple copies of
192     solver, each with its own different seed and then passing in the
193     solutions and cuts so that the main solver has a richer set of solutions
194     and possibly stronger cuts. This is switched on by setting
195     -multipleRootPasses. These can also be done in parallel.
196 
197   * Few changes to presolve for special variables and badly scaled problems
198     (in CoinUtils).
199
200   * New option -extraVariables <number> which switches on a trivial
201    re-formulation that introduces extra integer variables to group together
202    variables with same cost.
203
204   * For some problems, cut generators and general branching work better if
205     the problem would be infeasible if the cost is too high. If the new
206     option -constraintFromCutoff is set, the objective function is added as a
207     constraint which rhs is set to the current cutoff value (objective value
208     of best known solution).
209
210 * Release 2.7.8:
211
212   * Change message when LP simplex iteration limit is hit from "Exiting on
213     maximum nodes" to "Exiting on maximum number of iterations"
214   * Fix for using overlapping SOS.
215   * Fixes in buildsystem.
216
217 * Release 2.7.7:
218
219   * Fix to report interruption on user event if SIGINT is received by
220     CbcSolver. model->status() should now be 5 if this event happened. Added
221     method CbcModel::sayEventHappened() to make cbc stop due to an 'user
222     event'.
223
224   * Other minor fixes.
225
226 * Release 2.7.6:
227
228   * Fixes to build system.
229
230   * Other minor fixes.
231
232 * Release 2.7.5:
233
234   * Fixes to get AMPL interface working again.
235
236   * More fixes to MSVC++ files.
237
238 * Release 2.7.4:
239
240   * Minor bugfixes.
241
242 * Release 2.7.3:
243
244   * Minor bugfixes.
245
246   * Fixes to MSVC++ files.
247
248 * Release 2.7.2:
249
250   * Allow row/column names for GMPL models.
251
252   * Added CbcModel::haveMultiThreadSupport() to indicate whether Cbc library
253     has been compiled with multithread support.
254
255   * Added CbcModel::waitingForMiniBranchAndBound() to indicate whether
256     sub-MIP heuristic is currently running.
257
258   * Cbc shell should work with readline if configured with
259     ```--enable-gnu-packages```.
260
261   * Support for compressed input files (.gz, .bz2) is now enabled by default.
262
263   * Fix problems with relative gap tolerance > 100% and further bugs.
264
265   * Fixes for MSVC++ Version 9 files.
266
267   * Minor fixes in buildsystem; update to BuildTools 0.7.1.
268
269 * Release 2.7.1:
270
271   * Fixes to MSVC++ files
272
273 * Release 2.7.0:
274
275   * License has been changed to the EPL.
276
277   * Support for MSVC++ version 10 added.
278
279   * Support for BuildTools version 0.7 to incorporate recent enhancements,
280     including proper library versioning in Linux, prohibiting installation of
281     private headers, etc.
282
283   * Updated externals to new stable versions of dependent projects.
284
285   * Improvements to heuristics.
286
287   * New options for cut generation.
288
289   * Improved reporting of results.
290
291   * Improvements to documentation.
292
293   * Minor bug fixes.
294
295
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