code: @Override
  	public void propagate(int evtmask) throws ContradictionException {
  		ISet ker = g.getMandatoryNodes();
  		ISet succ;
  		for (int i : ker) {
  			succ = g.getMandSuccOf(i);
  			for (int j : succ) {
  				g.enforceArc(j, i, this);
  			}
  		}
  		gdm.unfreeze();
  	}
docs: ***********************************************************************************