Opened 11 years ago

Closed 11 years ago

#69 closed defect (fixed)

CBC 2.2.2 returns sub-optimal solution

Reported by: knark Owned by: somebody
Priority: major Component: component1
Version: 2.0 Keywords:
Cc:

Description

CBC 2.2.2 returns an objective value of -960 for the attached small MIP model while the optimal objective value is -1160. I used MS V8 on Windows.

Coin Cbc and Clp Solver version 2.20.00, build Feb 25 2009
command line - cbcsolve cbc00001.mps -solve
At line 1 NAME          BLANK
At line 2 ROWS
At line 5 COLUMNS
At line 17 RHS
At line 19 BOUNDS
At line 31 ENDATA
Problem BLANK has 1 rows, 11 columns and 11 elements
Coin0008I BLANK read with 0 errors
Continuous objective value is -1194.03 - 0.00 seconds
Optimal - objective value -1194.03
Cgl0004I processed model has 0 rows, 0 columns (0 integer) and 0 elements
Cbc3007W No integer variables - nothing to do
Cuts at root node changed objective from -960 to -1.79769e+308
Probing was tried 0 times and created 0 cuts of which 0 were active after adding rounds of cuts (0.000 seconds)
Gomory was tried 0 times and created 0 cuts of which 0 were active after adding rounds of cuts (0.000 seconds)
Knapsack was tried 0 times and created 0 cuts of which 0 were active after adding rounds of cuts (0.000 seconds)
Clique was tried 0 times and created 0 cuts of which 0 were active after adding rounds of cuts (0.000 seconds)
MixedIntegerRounding2 was tried 0 times and created 0 cuts of which 0 were active after adding rounds of cuts (0.000 seconds)
FlowCover was tried 0 times and created 0 cuts of which 0 were active after adding rounds of cuts (0.000 seconds)
TwoMirCuts was tried 0 times and created 0 cuts of which 0 were active after adding rounds of cuts (0.000 seconds)
Result - Finished objective -960 after 0 nodes and 0 iterations - took 0.00 seconds (total time 0.00)
Total time 0.00

The CBC version at COIN-OR returns the correct value of -1160:

Coin Cbc and Clp Solver version 1.01.00, build Aug 18 2006 command line - /home/neos/neos-bin/cbc cbc.mps 
At line 1 NAME          BLANK
At line 2 ROWS
At line 5 COLUMNS
At line 17 RHS
At line 19 BOUNDS
At line 31 ENDATA
Problem BLANK has 1 rows, 11 columns and 11 elements
Model was imported from ./cbc.mps in 0 seconds
Optimal - objective value -1194.03
Cgl0004I processed model has 1 rows, 11 columns (11 integer) and 11 elements processed model has 1 rows, 11 columns and 11 elements Optimal - objective value -1184 11 integer variables
  - solution found
Cbc0012I Integer solution of -1160 found by heuristic after 0 iterations and 0 nodes (0.01 seconds) 

Attachments (1)

cbc00001.mps (1.2 KB) - added by knark 11 years ago.

Download all attachments as: .zip

Change History (3)

Changed 11 years ago by knark

comment:1 in reply to: ↑ description Changed 11 years ago by knark

The CBC version at COIN-OR returns the correct value of -1160:

Ups, I meant NEOS.

comment:2 Changed 11 years ago by forrest

  • Resolution set to fixed
  • Status changed from new to closed

trunk seems okay - should be moving to stable

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