source: releases/2.10.0/README.md

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1# CBC Version 2.10.0 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 BUILD 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## DOWNLOAD
15
16[ ![Download](https://api.bintray.com/packages/coin-or/download/Cbc/images/download.svg) ](https://bintray.com/coin-or/download/Cbc/2.10)
17
18Binaries for most platforms are available for download from [Bintray](https://bintray.com/coin-or/download/Cbc)
19
20## CITE
21
22[![DOI](https://zenodo.org/badge/30382416.svg)](https://zenodo.org/badge/latestdoi/30382416)
23
24## DOCUMENTATION
25
26For a quick start guide, please see the INSTALL file in this distribution. A
27(somehwat outdated) user's manual is available here:
28
29http://www.coin-or.org/Cbc
30
31More up-to-date automatically generated documentation of the source code can
32be found here:
33
34http://www.coin-or.org/Doxygen/Cbc/
35
36Further information can be found here:
37
38http://projects.coin-or.org/Cbc
39
40## SUPPORT
41
42### List Serve
43
44CBC users should use the Cbc mailing list. To subscribe, go to
45http://list.coin-or.org/mailman/listinfo/cbc
46
47### Bug Reports
48
49Bug reports should be reported on the CBC development web site at
50
51https://projects.coin-or.org/Cbc/newticket
52
53## CHANGELOG
54
55 * Release 2.10.0
56   * Improved handling of SOS, starting point, and symmetries
57   * Improved performance of primal heuristics regarding the handling of
58     implicit integer variables
59   * Mini-B&B is now disabled when solving with multiple threads
60   * Changed default value for zero half cuts parameter from off to ifmove
61   * Added CbcModel::postProcessedSolver() to obtained LP after presolve
62   * New option "PrepNames" to indicate whether column names should be
63     kept in the pre-processed model
64   * New option "sosPrioritize" to determine how to prioritize SOS
65   * Added new event "generatedCuts"
66   * CbcSolver can now read compressed .lp files (GZIP, BZIP2)
67   * New functions in the C interface: Cbc_readLp, Cbc_writeLp,
68     Cbc_addCol, Cbc_addRow, Cbc_getNumIntegers, Cbc_bestSolution,
69     Cbc_getObjValue, Cbc_getRowNz, Cbc_getRowIndices, Cbc_getRowCoeffs,
70     Cbc_getRowRHS, Cbc_getRowSense, Cbc_getColNz, Cbc_getColIndices,
71     Cbc_getColCoeffs, Cbc_getReducedCost, Cbc_numberSavedSolutions,
72     Cbc_savedSolution, Cbc_savedSolutionObj, Cbc_setMIPStart,
73     Cbc_setMIPStartI, Cbc_addCutCallback, Osi_getNumCols, Osi_getColName,
74     Osi_getColLower, Osi_getColUpper, Osi_isInteger, Osi_getNumRows,
75     Osi_getRowNz, Osi_getRowIndices, Osi_getRowCoeffs, Osi_getRowRHS,
76     Osi_getRowSense, Osi_getColSolution, OsiCuts_addRowCut,
77     Cbc_getAllowableGap, Cbc_setAllowableGap, Cbc_getAllowableFractionGap,
78     Cbc_setAllowableFractionGap, Cbc_getAllowablePercentageGap,
79     Cbc_setAllowablePercentageGap, Cbc_getCutoff, Cbc_setCutoff,
80     Cbc_getMaximumNodes, Cbc_setMaximumNodes, Cbc_getMaximumSolutions,
81     Cbc_setMaximumSolutions, Cbc_getLogLevel, Cbc_setLogLevel,
82     Cbc_getMaximumSeconds, Cbc_setMaximumSeconds
83   * New example inc.cpp to illustrate solution callback
84   * New example driver5.cpp to illustrate user-defined branching rule
85   * New example clpdriver.cpp to illustrate use of ClpEventHandler
86   * Added support for using OsiHiGHS with CbcGeneric
87   * Added MSVC 14 project files
88   * Bugfixes
89   
90 * Release 2.9.10
91   * Fix a numerical issue
92   * Fix some memory leaks
93   * Fix issue when root node is obviously infeasible
94   * Performance improvements for mini-B&B
95   * Fix name of bound in final message
96   * Fix names in preprocessed problem
97
98 * Release 2.9.9
99
100   * Fixes for SOS2
101   * Updates to mipstart
102   * Switching to new build system
103   * Updates for CI
104
105 * Release 2.9.8
106
107   * Update to most current releases of dependencies
108   * Small bug fixes
109   * Add support for automatic build and test with Travis and Appveyor
110
111 * Release 2.9.7
112
113   * Small bug fixes
114   * Option to switch to line buffered output
115
116 * Release 2.9.6
117
118   * Small bug fixes
119
120 * Release 2.9.5
121
122   * Small bug fixes
123
124 * Release 2.9.4
125
126   * Small fixes for stability
127   * Fixes for Doygen documentation generation
128
129 * Release 2.9.3
130
131   * Minor bug fixes
132
133 * Release 2.9.2
134
135   * Fix for proper installation with ```DESTDIR```
136
137 * Release 2.9.1
138
139   * Fix for dependency linking
140   * Minor bug fixes
141
142 * Release 2.9.0
143
144   * Introduced specialized branching methods for dealing with "big Ms".
145   * Introduced new methods for dealing with symmetry (requires installation of [nauty](http://pallini.di.uniroma1.it/))
146   * Introduction of conflict cuts (off by default, turn on with `-constraint conflict`)
147
148 * Release 2.8.13
149
150   * Improved message handling
151   * Miscellaneous bug fixes.
152
153 * Release 2.8.12
154
155   * Update for dependencies.
156
157 * Release 2.8.11
158
159   * Major overhaul of C interface
160   * Fixes to SOS
161   * Miscellaneous bug fixes
162
163 * Release 2.8.10
164
165   * More changes related to thread safety.
166   * Fix bug in build system with Visual Studio compiler.
167   * Miscellaneous bug fixes.
168
169 * Release 2.8.9
170
171   * Attempt to make Cbc thread safe.
172   * Add parallel examples.
173   * Add CbcSolverUsefulInfo.
174   * Bug fixes.
175
176 * Release 2.8.8
177
178   * Added example to show how to use Cbc with installed libraries in MSVC++
179   * Fixed inconsistency in addition of libCbcSolver to dependencies in
180     {{{cbc_addlibs.txt}}}.
181
182 * Release 2.8.7
183
184   * Changed so that Doxygen builds LaTex
185   * Fixes for build system
186
187 * Release 2.8.6
188
189   * Added option to explicitly link dependencies to comply with packaging
190     requirements on Fedora and Debian, as well as allow building of MinGW
191     DLLs.
192
193 * Release 2.8.5
194
195   * Minor fixes to build system
196
197 * Release 2.8.4
198
199   * Small bug fixes
200   * Upgrades to build system
201
202 * Release 2.8.3:
203
204   * Fix for handling SOS.
205
206 * Release 2.8.2:
207
208   * Fixed recognition of Glpk source in main configure.
209   * Minor bug fixes in CoinUtils, Clp, and Cbc.
210
211 * Release 2.8.1:
212
213   * Minor bug fixes
214
215 * Release 2.8.0:
216
217   * Introduced new secondaryStatus 8 to indicate that solving stopped due to
218     an iteration limit.
219   * Solution pool is now accessible via the command line and the CbcMain*
220     interface.
221   * New mipstart option to read an initial feasible solution from a file.
222     Only values for discrete variables need to be provided.
223
224   * Added Proximity Search heuristic by Fischetti and Monaci (off by
225     default): The simplest way to switch it on using stand-alone version is
226     ```-proximity on```.
227
228     Proximity Search is the new "No-Neighborhood Search" 0-1 MIP refinement
229     heuristic recently proposed by Fischetti and Monaci (2012). The idea is
230     to define a sub-MIP without additional constraints but with a modified
231     objective function intended to attract the search in the proximity of the
232     incumbent. The approach works well for 0-1 MIPs whose solution landscape
233     is not too irregular (meaning the there is reasonable probability of
234     finding an improved solution by flipping a small number of binary
235     variables), in particular when it is applied to the first heuristic
236     solutions found at the root node.
237   
238   * An implementation of Zero-Half-Cuts by Alberto Caprara is now available.
239     By default, these cuts are off. To use add to your command line
240     -zerohalfCuts root (or other options) or just -zero. So far, they may
241     help only on a small subset of problems and may need some tuning.
242
243     The implementation of these cuts is described in G. Andreello, A.
244     Caprara, and M. Fischetti "Embedding Cuts in a Branch and Cut Framework:
245     a Computational Study with {0,1/2}-Cuts" INFORMS Journal on Computing
246     19(2), 229-238, 2007 http://dx.doi.org/10.1287/ijoc.1050.0162
247
248   * An alternative implementation of a reduce and split cut generator by
249     Giacomo Nannicini is now available. By default, these cuts are off. To
250     use add to your command line -reduce2AndSplitCuts root (or other
251     options).
252
253     The implementation of these cuts is described in G. Cornuejols and G.
254     Nannicini "Practical strategies for generating rank-1 split cuts in
255     mixed-integer linear programming" Mathematical Programming Computation
256     3(4), 281-318, 2011 http://dx.doi.org/10.1007/s12532-011-0028-6
257
258   * An alternative robust implementation of a Gomory cut generator by Giacomo
259     Nannicini is now available. By default, these cuts are off. To use add to
260     your command line -GMI root (or other options).
261
262     The implementation of these cuts is described in G. Cornuejols, F.
263     Margot, and G. Nannicini "On the safety of Gomory cut generators"
264     http://faculty.sutd.edu.sg/~nannicini/index.php?page=publications
265
266   * To encourage the use of some of the more exotic/expensive cut generators
267     a parameter -slowcutpasses has been added. The idea is that the code does
268     these cuts just a few times - less than the more usual cuts. The default
269     is 10. The cut generators identified by "may be slow" at present are just
270     Lift and project and ReduceAndSplit (both versions).
271   
272   * Allow initialization of random seed by user. Pseudo-random numbers are
273     used in Cbc and Clp. In Clp they are used to break ties in degenerate
274     problems, while in Cbc heuristics such as the Feasibility Pump use them
275     to decide whether to round up or down. So if a different pseudo-random
276     seed is given to Clp then you may get a different continuous optimum and
277     so different cuts and heuristic solutions. This can be switched on by
278     setting randomSeed for Clp and/or randomCbcSeed for Cbc. The special
279     value of 0 tells code to use time of day for initial seed.
280   
281   * Building on this idea, Andrea Lodi, Matteo Fischetti, Michele Monaci,
282     Domenico Salvagnin, Yuji Shinano, and Andrea Tramontani suggest that this
283     idea be improved by running at the root node with multiple copies of
284     solver, each with its own different seed and then passing in the
285     solutions and cuts so that the main solver has a richer set of solutions
286     and possibly stronger cuts. This is switched on by setting
287     -multipleRootPasses. These can also be done in parallel.
288 
289   * Few changes to presolve for special variables and badly scaled problems
290     (in CoinUtils).
291
292   * New option -extraVariables <number> which switches on a trivial
293    re-formulation that introduces extra integer variables to group together
294    variables with same cost.
295
296   * For some problems, cut generators and general branching work better if
297     the problem would be infeasible if the cost is too high. If the new
298     option -constraintFromCutoff is set, the objective function is added as a
299     constraint which rhs is set to the current cutoff value (objective value
300     of best known solution).
301
302 * Release 2.7.8:
303
304   * Change message when LP simplex iteration limit is hit from "Exiting on
305     maximum nodes" to "Exiting on maximum number of iterations"
306   * Fix for using overlapping SOS.
307   * Fixes in buildsystem.
308
309 * Release 2.7.7:
310
311   * Fix to report interruption on user event if SIGINT is received by
312     CbcSolver. model->status() should now be 5 if this event happened. Added
313     method CbcModel::sayEventHappened() to make cbc stop due to an 'user
314     event'.
315
316   * Other minor fixes.
317
318 * Release 2.7.6:
319
320   * Fixes to build system.
321
322   * Other minor fixes.
323
324 * Release 2.7.5:
325
326   * Fixes to get AMPL interface working again.
327
328   * More fixes to MSVC++ files.
329
330 * Release 2.7.4:
331
332   * Minor bugfixes.
333
334 * Release 2.7.3:
335
336   * Minor bugfixes.
337
338   * Fixes to MSVC++ files.
339
340 * Release 2.7.2:
341
342   * Allow row/column names for GMPL models.
343
344   * Added CbcModel::haveMultiThreadSupport() to indicate whether Cbc library
345     has been compiled with multithread support.
346
347   * Added CbcModel::waitingForMiniBranchAndBound() to indicate whether
348     sub-MIP heuristic is currently running.
349
350   * Cbc shell should work with readline if configured with
351     ```--enable-gnu-packages```.
352
353   * Support for compressed input files (.gz, .bz2) is now enabled by default.
354
355   * Fix problems with relative gap tolerance > 100% and further bugs.
356
357   * Fixes for MSVC++ Version 9 files.
358
359   * Minor fixes in buildsystem; update to BuildTools 0.7.1.
360
361 * Release 2.7.1:
362
363   * Fixes to MSVC++ files
364
365 * Release 2.7.0:
366
367   * License has been changed to the EPL.
368
369   * Support for MSVC++ version 10 added.
370
371   * Support for BuildTools version 0.7 to incorporate recent enhancements,
372     including proper library versioning in Linux, prohibiting installation of
373     private headers, etc.
374
375   * Updated externals to new stable versions of dependent projects.
376
377   * Improvements to heuristics.
378
379   * New options for cut generation.
380
381   * Improved reporting of results.
382
383   * Improvements to documentation.
384
385   * Minor bug fixes.
386
387
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