}
DAG dag= new DAG();
for (int i= 0; i < array.length; i++) {
RulerColumnDescriptor desc= (RulerColumnDescriptor) array[i];
dag.addVertex(desc);
Set before= desc.getPlacement().getConstraints();
for (Iterator it= before.iterator(); it.hasNext();) {
RulerColumnPlacementConstraint constraint= (RulerColumnPlacementConstraint) it.next();
String id= constraint.getId();