Infeasible problem with status "Optimal"

[Kuifje02]

This is an issue from or.stackexchange here : https://or.stackexchange.com/questions/7810/problem-is-infeasible-with-gurobi-feasible-with-cbc-but-cant-access-objective/7827#7827

The problem attached (lp and mps ) is definitely infeasible, but CBC returns:

- Status: ok
  Message: CBC 2.10.5
  Termination condition: optimal
  Id: 0
  Error rc: 0
  Time: 0.011972904205322266

Problem is feasible and solution is optimal

However when using version 2.10.3, CBC does return infeasible :

prob.zip

[jjhforrest]

stand alone cbc says infeasible with stable 10.5

Welcome to the CBC MILP Solver Version: 2.10.5 Build Date: Apr 23 2021

command line - debug/bin/cbc /tmp/probx/test.lp (default strategy 1)  CoinLpIO::readLp(): Maximization problem reformulated as minimization Coin0009I Switching back to maximization to get correct duals etc Problem is infeasible - 0.01 seconds Total time (CPU seconds):       0.02   (Wallclock seconds): 0.01

On 11/02/2022 17:10, RomainM wrote:

This is an issue from or.stackexchange here : https://or.stackexchange.com/questions/7810/problem-is-infeasible-with-gurobi-feasible-with-cbc-but-cant-access-objective/7827#7827

The problem attached is definitely infeasible, but CBC returns:

|- Status: ok Message: CBC 2.10.5 Termination condition: optimal Id: 0 Error rc: 0 Time: 0.011972904205322266 Problem is feasible and solution is optimal |

prob.zip https://github.com/coin-or/Cbc/files/8050413/prob.zip

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[tristan-bifrost]

Hi, OP from or.stackexchange here. This is stand alone cbc output on my side Cheers =)

[jjhforrest]

Use the .lp you put up - or take out line 2 OBJSENSE  is not mps standard - you have to specify min/max in run

On 11/02/2022 18:47, Meth-GitHub wrote:

Hi, OP from or.stackexchange here. This is stand alone cbc output on my side Cheers =) Ca192249 https://user-images.githubusercontent.com/99499156/153651180-17ca6e3b-1ef0-4b7c-83fb-f6000ae39d18.png

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[tristan-bifrost]

Thanks, indeed I have a similar result as yours with the lp file