Specifying types of variables

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The following types of variables fall into the mixed integer programming category in GAMS

Binary variables (Binary).  These can only take on values of 0 or 1.
Integer variables (Integer).  These can take on integer values between a lower and an upper bound.  By default these variables are bounded in GAMS to the interval 0 to 100.
Specially Ordered Sets Type 1 (SOS1).  Groups of variables where only one member in each group can have a nonzero value in the solution.
Specially Ordered Sets Type 2 (SOS2).  Groups of variables where only two variables in the group can have nonzero solution levels and they must be adjacent.
Semi-continuous variables (Semicont).  Variables that must either be zero or can take on a continuous value above a threshold value.
Semi-integer variables (Semiint).  Variables that must be must either be zero or can take on a integer value above a threshold limit.

Each is discussed below.

 

Binary variables

Integer variables

Specially ordered set variables of type 1 (SOS1)

Specially ordered set variables of type 2 (SOS2)

Semi-continuous variables

Semi-integer variables