[Cbc] Preprocessing infeasibility

[John Forrest]

A preprocessing error was fixed recently which might have something to 
do with the problem.  Try the latest Cbc/stable.  Also try switching off 
preprocessing.  If that gives a feasible solution then there is 
obviously a bug - I can look at problem.

John Forrest



On 10/11/15 12:28, Mona Rahn wrote:
> Hello,
>
> I have an LP where I get the message
>
> "Cut generators found to be infeasible!
> Preprocessing says infeasible or unbounded"
>
> The problem can't be unbounded (it's a minimization problem and the 
> objective is of the form a*x, a>0, x>=0).
>
> So I tried to analyze the infeasibility via a (kind of) Lagrangian 
> relaxation (for every constraint, I added two variables in [0,inf), 
> one with positive and one with negative coefficient, that appear also 
> in the objective function with a positive coefficient; by making them 
> large enough, the constraint is feasible). So unless I made an error, 
> the relaxed problem cannot be infeasible. But upon solving this I get 
> the same message again.
>
> Can somebody please help?
>
> Thank you in advance!
>
>
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