CBC version 2.4.2, OSI version 0.102.3 - OsiCbc declares problem infeasible that Cbc solves to optimal fine (tiny problem)

[svigerske]

Issue created by migration from Trac.

Original creator: @mgalati13

Original creation time: 2010-08-24 21:21:42

Version:

The code to repeat the issue can be found in DIP repository at bugs/OsiCbc.

[magala`@`orclus71 OsiCbc]$ ./a.out
Clp0000I Optimal - objective value 2
Cbc0009I Objective coefficients multiple of 1
Clp0000I Optimal - objective value 2
Cbc0004I Integer solution of 2 found after 0 iterations and 0 nodes (0.00 seconds)
Cbc0001I Search completed - best objective 2, took 0 iterations and 0 nodes (0.00 seconds)
Cbc0035I Maximum depth 0, 0 variables fixed on reduced cost
Clp0000I Optimal - objective value 2
Clp0000I Optimal - objective value 2
Clp0006I 0  Obj 2.57476 Dual inf 0.10562 (1)
Clp0006I 2  Obj 2.57476
Clp0000I Optimal - objective value 2.57476
Cbc0006I The LP relaxation is infeasible or too expensive
a.out: main.cpp:47: int main(int, char**): Assertion `!osi.isProvenPrimalInfeasible()' failed.
Aborted

[svigerske]

Comment by @mgalati13 created at 2010-08-24 21:22:55

To repeat the issue, run this:
https://projects.coin-or.org/Dip/browser/trunk/Dip/bugs/OsiCbc/main.cpp

[svigerske]

Looks ok with current Cbc/master:

$ ./a.out 
 Warning: Use of OsiCbc is deprecated.
 To enjoy the full performance of Cbc, use the CbcSolver interface.
Clp0000I Optimal - objective value 2
Cbc0045I Heuristic rounding took 2e-06 seconds (no good)
Clp0000I Optimal - objective value 2
Cbc0004I Integer solution of 2 found after 0 iterations and 0 nodes (0.00 seconds)
Cbc0001I Search completed - best objective 2, took 0 iterations and 0 nodes (0.00 seconds)
Cbc0035I Maximum depth 0, 0 variables fixed on reduced cost
Clp0000I Optimal - objective value 2
Clp0000I Optimal - objective value 2
 Warning: Use of OsiCbc is deprecated.
 To enjoy the full performance of Cbc, use the CbcSolver interface.
Clp0006I 0  Obj 2.57476 Dual inf 0.1056199 (1)
Clp0006I 2  Obj 2.57476
Clp0000I Optimal - objective value 2.57476
Cbc0006I The LP relaxation is infeasible or too expensive
Cbc0045I Solution of 2 already found by heuristic
Clp0000I Optimal - objective value 2.57476
Clp0000I Optimal - objective value 2.57476