Binary variables Y(J);

If some or all variables of Y are not included in any equation or constraint defined in GAMS section they will be eliminated from the model, and LogMIP compiler will show an error even when they handle disjunction terms. To avoid that, you must write the following constraint:

DUMMY.. SUM(J, Y(J)) =G= 0;

which should be always satisfied.

Another example could be:

Binary variables y, w, z;

DUMMY .. y + w + z =G=0;

A combination of the previous examples could be:

DUMMY.. y + w + z + SUM(j, Y(j)) =G= 0;