[Cbc] Strange behaviour of cbc

[John Forrest]

Nicolas,

Unable to reproduce with a stable version.

With trunk I got the behaviour as the max time is passed across to 
solver so it may stop in middle of verifying solution - so I have 
removed that in trunk.

John Forrest
On 31/10/2019 15:20, DERHY NICOLAS wrote:
> Hi,
> 
> I am using latest version of cbc (Cbc-2.10.3-win32-msvc15).
> 
> I sometimes meet a very strange behavior when using it.
> 
> For example, with the data attached and the following command line :
> 
> cbc.exe "Model.mps" -preprocess off -ratio 1E-05 -seconds 30 -minimize 
> -solve -printingOptions all -solution "solution.txt"
> 
> It stops after 30 seconds telling either the problem is infeasible 
> (Result - Problem proven infeasible), either it reaches the time limit 
> (Result - Stopped on time limit).
> 
> In both cases, the objective value seems very strange and the solution 
> is not valid (some binary variables are not 0 or 1).
> 
> But when I read the log, it seems that some integer solutions have been 
> found so I do not understand the final result.
> 
> When I increase the max time to 60 seconds, problem is solved : Result - 
> Optimal solution found.
> 
> I attached the different log files.
> 
> In the past, I had similar issues with previous versions like 2.9.8. I 
> had to downgrade to 2.8.13 to avoid them.
> 
> I know that setting “on” the preprocess allow to avoid this in that case 
> but I do not want to do it for some other reasons.
> 
> If someone know how to avoid this, it would be great !
> 
> Nicolas
> 
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