[Coin-discuss] sbb assertion - small problem

[Matthew Galati]

Hi Folks,

Attached is the mps for a small b-matching IP. Using Sbb/Test, I get an 
assertion at line SbbModel.cpp:591.

[mgalati at localhost Test]$ ../sbb -import match.mps
-----------------------------
Default solver is clp
Coin0001I At line 1 NAME          BLANK
Coin0001I At line 2 ROWS
Coin0001I At line 26 COLUMNS
Coin0001I At line 260 RHS
Coin0001I At line 272 BOUNDS
Coin0001I At line 504 ENDATA
Coin0002I Problem BLANK has 22 rows, 231 columns and 462 elements
Sbb0009I Objective coefficients multiple of 1
Sbb0016I Integer solution of -1 found by strong branching after 0 
iterations and 0 nodes
sbb: SbbModel.cpp:591: void SbbModel::branchAndBound(): Assertion 
`!newNode || newNode->objectiveValue() < getCutoff()' failed.
Aborted
-----------------------------

 From the log, it seems to solve it, but dies in this assertion before 
it exits.



Cplex (v8.1.0) agrees that the solution is -1:
-----------------------------
Problem 'match.mps' read.
Read time =    0.00 sec.
Tried aggregator 1 time.
No MIP presolve or aggregator reductions.
Presolve time =    0.00 sec.
Dual steepest-edge pricing selected.
MIP emphasis: balance optimality and feasibility
Root relaxation solution time =    0.00 sec.
 
        Nodes                                         Cuts/
   Node  Left     Objective  IInf  Best Integer     Best Node    
ItCnt     Gap         Variable B Parent  Depth
 
      0     0       -1.0000     6                     -1.0000       49
*     0+    0                   0       -1.0000       -1.0000       
49    0.00%
 
Integer optimal solution:  Objective =   -1.0000000000e+00
Solution time =    0.00 sec.  Iterations = 49  Nodes = 0
-----------------------------


Thanks,
Matthew

-- 
Matthew Galati -- Optimization Developer
SAS Institute -- Analytical Solutions / Operations R & D
Office R4112 O: 919-531-0332 F: 919-677-4444
URL: http://sagan.ie.lehigh.edu/mgalati/ 

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