[Scip] why might this short 3 constraint program be infeasible?

[Gerald Gamrath]

Hi George,

the reason is simple: 'a' needs to take on the value of -14.666667 in 
order to make the constraint "aval" feasible. However, if you do not 
specify a lower bound for a variable, ZIMPL assumes the variable to be 
nonnegative (which is consistent to the lp file format, by the way).

In order to get a free variable, you need to specify a lower bound of - 
infinity, i.e.,
var a >= -infinity;

If you do this, everything works fine.

Best,
Gerald




Am 16.09.2013 21:58, schrieb George Nychis:
> Hi all,
>
> I'm trying to figure out why the solution to this short attached ZMPL 
> example is infeasible.  I believe that 'a' taking on the value 
> of 14.666667 provides an answer, but I don't know hot SCIP is meant to 
> handle that repeating digit.
>
> - George
>
>
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