Minus minus = null;
if (useSortedMinus) {
// insert sort operator to preprocess for SortedMinus
final Sort sortLeft = new Sort();
final Sort sortRight = new Sort();
minus = new SortedMinus(sortLeft, sortRight);
connection.connectAndSetAsNewOperatorConnection(minus, 1);
connection.connectAndSetAsNewOperatorConnection(sortRight);
n.accept(this, connection, graphConstraint);
connection.setOperatorConnection(minus, 0);