[Cbc] Possible CbcBranchDynamic.cpp BUG

[John Forrest]

Should be fixed in 2.7 and trunk
On Fri, 2011-09-02 at 20:11 -0300, Haroldo Santos wrote:
> Did more experiments to see when this bug occurs.
> 
> To turn off all heuristics and cuts it makes it happens faster.
> 
> This is an instance
> http://www.decom.ufop.br/haroldo/files/sprint_hidden06.lp.gz
> which is quickly solved by CPLEX and has optimal objective function
> value   130.
> 
> CBC crashes at this point:
> 
> Cbc0010I After 1700 nodes, 656 on tree, 249 best solution, best
> possible 99.390873 (139.08 seconds)
> cbc: CbcBranchDynamic.cpp:551: virtual int
> CbcBranchDynamicDecision::betterBranch(CbcBranchingObject*,
> CbcBranchingObject*, double, int, double, int): Assertion `distance >=
> 0.0' failed
> 
> 
> 
> 
> 
> 
> 
> 
> On Wed, Aug 24, 2011 at 5:43 PM, Haroldo Santos
> <haroldo.santos at gmail.com> wrote:
>         Dear Forrest/CBC Developers,
>         
>         There is this assertion failing  in :
>         CbcBranchDynamic.cpp:551: virtual int
>         CbcBranchDynamicDecision::betterBranch(CbcBranchingObject*,
>         CbcBranchingObject*, double, int, double, int): Assertion
>         `distance >= 0.0' failed.
>          
>         when I'm solving this MIP:
>         http://www.decom.ufop.br/haroldo/files/sprint_hidden04.lp.gz
>           
>         
>         I did some debug and discover that this fails because at a
>         given point of the search the distance is  -0.415667  .
>         
>         Cbc0010I After 10000 nodes, 4845 on tree, 180 best solution,
>         best possible 142.25 (1909.96 seconds)
>         Cbc0010I After 10100 nodes, 4849 on tree, 180 best solution,
>         best possible 142.25 (1919.14 seconds)
>         
>         Tested in Linux with CBC 2.7 stable, default compilation
>         options and no ThirdParty software included.
>         
>         The stack trace at this point is:
>         #0  0x00007ffff779c5cb in
>         CbcBranchDynamicDecision::betterBranch (this=0xb3eee10,
>         thisOne=
>             0x12d60060, changeUp=0, numInfUp=205, changeDown=0,
>         numInfDown=211) at CbcBranchDynamic.cpp:555
>         #1  0x00007ffff784bf40 in CbcNode::chooseDynamicBranch
>         (this=0x12d9a290, model=0x60dcd0, 
>             lastNode=0x12aa7510, numberPassesLeft=4) at
>         CbcNode.cpp:3178
>         #2  0x00007ffff783521c in CbcModel::chooseBranch
>         (this=0x60dcd0, newNode=@0x7fffffff53a0, 
>             numberPassesLeft=5, oldNode=0x12aa7510, cuts=...,
>         resolved=@0x7fffffff4d18, lastws=0x12e21f40, 
>             lowerBefore=0x12ac54b0, upperBefore=0x1396c2e0,
>         branches=@0x7fffffff4b08) at CbcModel.cpp:12642
>         #3  0x00007ffff783b052 in CbcModel::doOneNode (this=0x60dcd0,
>         baseModel=0x60dcd0, 
>             node=@0x7fffffff5298, newNode=@0x7fffffff53a0) at
>         CbcModel.cpp:14299
>         #4  0x00007ffff78108f5 in CbcModel::branchAndBound
>         (this=0x60dcd0, doStatistics=0)
>             at CbcModel.cpp:3797
>         #5  0x00007ffff7b7be8b in CbcMain1 (argc=11,
>         argv=0x7fffffffdef8, model=..., 
>             callBack=0x7ffff7b67569 <dummyCallBack(CbcModel*, int)>)
>         at CbcSolver.cpp:5589
>         #6  0x00007ffff7b67bb5 in CbcMain1 (argc=11,
>         argv=0x7fffffffdef8, model=...) at CbcSolver.cpp:1111
>         #7  0x0000000000400f47 in main (argc=11, argv=0x7fffffffdef8)
>         at CoinSolve.cpp:336
>         
>         Cheers, 
>         
>         Haroldo
>         
>         -- 
>         =============================================================
>         Haroldo Gambini Santos
>         Computing Department - Universidade Federal de Ouro Preto -
>         UFOP
>         email: haroldo [at ] iceb.ufop.br
>         home/research page: www.decom.ufop.br/haroldo/
>          
>         "Computer science is no more about computers than astronomy 
>         is about telescopes." Edsger Dijkstra
>          
> 
> 
> 
> -- 
> =============================================================
> Haroldo Gambini Santos
> Computing Department - Universidade Federal de Ouro Preto - UFOP
> email: haroldo [at ] iceb.ufop.br
> home/research page: www.decom.ufop.br/haroldo/
>  
> "Computer science is no more about computers than astronomy 
> is about telescopes." Edsger Dijkstra
>  
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