[Coin-discuss] Controlling printing for CbcStrategyDefault

[Kish Shen]

John,

I have now generated the logged calls to COIN libraries, which does produce 
the error messages. These logged calls is in the form of a C program, and can 
be compiled and then run to reproduce the problem.

I did it with cap6000, which unfortunately is quite large -- the logged calls 
file is about 6M in size, but it should be reduced in size significantly if  
gzipped. So if you would like to look at this, please let me know and I can 
send it to you. 

I have the RedSplit cut generator turned on, and for cap6000, I seem to get an 
extra warning message about an empty problem:

Clp6002E 1 bad bound pairs or bad objectives were found - first at C1987
Clp6002E 1 bad bound pairs or bad objectives were found - first at C2078
Clp6002E 2 bad bound pairs or bad objectives were found - first at C4008
Clp6002E 1 bad bound pairs or bad objectives were found - first at C4008
Clp3002W Empty problem - 0 rows, 1 columns and 0 elements
Clp6002E 1 bad bound pairs or bad objectives were found - first at C2982
Clp6002E 2 bad bound pairs or bad objectives were found - first at C2888
Clp6002E 2 bad bound pairs or bad objectives were found - first at C4679
Clp6002E 1 bad bound pairs or bad objectives were found - first at C4287

Cheers,

Kish

> On Sunday 09 July 2006 21:48, John J Forrest wrote:
> > Kish,
> >
> > I can not reproduce error messages.
> >
> >
> >
> >
> >
> >              Kish Shen
> >              <kish.shen at crossc
> >              oreop.com>                                                
> > To Sent by:                  Discussions about open source
> > coin-discuss-boun         software for Operations Research
> > ces at list.coin-or.         <coin-discuss at list.coin-or.org> org            
> >                                            cc
> >
> >                                                                   
> > Subject 07/09/06 02:17 AM         Re: [Coin-discuss] Controlling printing
> > for CbcStrategyDefault
> >
> >              Please respond to
> >              Discussions about
> >                 open source
> >                software for
> >                 Operations
> >                  Research
> >              <coin-discuss at lis
> >               t.coin-or.org>
> >
> >
> >
> >
> >
> >
> > Hi,
> >
> > On Saturday 08 July 2006 07:31, Kish Shen wrote:
> > > One question about this preprocessing: do you expect it to improve the
> > > performance? In my case, I have already called CglPreprocess on the
> >
> > problem
> >
> > > when it was first copied from the OsiClpSolver to the CbcModel, and in
> >
> > the
> >
> > > rather limited test examples I have been running (mainly used to test
> > > if
> >
> > my
> >
> > > changes are working, rather than for measuring performances), where
> > > some MIPLIB problems are solved (but they are modelled in our ECLiPSe
> > > programming language, rather than read in from an MPS file), doing this
> > > second preprocessing in CbcStrategy does not improve the solving times,
> >
> > and
> >
> > > in fact for one problem (noswot), it slows the solving time time from
> > > 33s to 54s.
> >
> > I decided to try out some more tests with my code. With the
> > CbcStrategyDefault
> > set for the CbcModel  (model is a CbcModel*):
> >
> >    (code taken and modified from sample2.cpp in Cbc Samples directory)
> >     // Set up pre-processing to find sos if wanted
> >     if (lpd->presolve) strategy.setupPreProcessing(2);
> >     //strategy.setupPrinting(*model, 0);
> >     model->setStrategy(strategy);
> >     model->branchAndBound();
> >
> > this generally solved the problems faster than if the strategy
> > preprocessing
> > and setStrategy code is commented out. However, for a couple of the
> > problems
> > I tried (versions of MIPLIB's cap6000 and aflow30a), I got what looks
> > like error messages from Clp:
> >
> > Clp6002E 1 bad bound pairs or bad objectives were found - first at C3013
> > Clp6002E 1 bad bound pairs or bad objectives were found - first at C1987
> > Clp6002E 1 bad bound pairs or bad objectives were found - first at C3863
> >
> > the actual objective value for the MIP problem after the search appears
> > to be
> > correct though. Is the above a potential problem, or are such messages
> > expected?
> >
> > aflow30a, in addition to generating Clp error messages like the above,
> > also
> >
> > ran much slower with the CbcStrategyDefault than without -- slowing down
> > from
> > 2000 seconds to 6500 seconds, the only problem to do so. Is this related
> > to
> >
> > the above messages?
> >
> > Cheers,
> >
> > Kish Shen
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