[Scip] Regarding expressing a constraint in a linear program

[Michael Armbruster]

Hi Tobias,

> Gaurav,
>
>> I am trying to use SCIP to solve a linear program. I have a linear program
>> in which all the variables are continuous
>> variables which are free to have values from 0 to infinity. Among those
>> there are two variables, only one of which can be non-zero. I am not sure
>> how to express this as a linear constraint. Could you help me with this?
>
> The probably best way would be to add an SOS1 constraint.   
> Unfortunately, SCIP currently
> does not support SOS1.

But one could add a constraint handler that implements SOS1  
constraints and at least declares solutions with both variables  
nonzero as infeasible, couldn't one? The constraint handler could also  
suggest branching on the two possibilities y1 = 0 and y2 = 0.

Best wishes,

Michael