[Cbc] Artificial variables

[Christos]

So why does it says about 1 infeasibility?

By saying unbounded, you mean that some bounds( column or row?) are wrong,
or that the problem's solution going to infinity?

How can i add a constrain that limits the objective, since objective is 
formed through the variable and is a matrix?
Should i have to know something about solver's classes?

Thank you very much for your immediate and helpful response.


On 10/8/2012 19:24, acw at ascent.com wrote:
> No single constraint is responsible for an infeasibility.  Consider a 
> system with one variable, and two constraints, X >= 7 and X <= 4. 
>  This system is obviously infeasible, but which of the two constraints 
> is at fault?
>
> In your case I suspect that the problem is unbounded rather than 
> infeasible, because you have so few constraints and so many variables. 
>  Unless the problem has a very special structure, a problem with fewer 
> constraints than variables is likely to be unbounded.
>
> You can check this by adding a constraint that limits your objective 
> to, say, 1e6.  If the problem now solves, then unboundedness is almost 
> certainly your difficulty.
>
>
> From: 	Christos <chtsolak at gmail.com>
> To: 	cbc at list.coin-or.org
> Date: 	08/10/2012 09:32 AM
> Subject: 	[Cbc] Artificial variables
>
>
> ------------------------------------------------------------------------
>
>
>
> Hi, i have a model with around 10000 variable and 1500 equations.
>
> But i get the messages on the photo when i run it:
> http://imageshack.us/photo/my-images/39/dascd.png/
>
> Is there any way to use artificial variable or something else in order
> to find the problematic equation?
>
> Thank you in advance
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