///////////////////////////////////////////////////////////////////
//// private methods ////
// Return true if any action has a guard which depends on input values.
protected boolean _hasInputDependentGuard() {
for (int i = 0; i < _actions.length; i++) {
Action action = _actions[i];
Expression[] guards = action.getGuards();
for (int j = 0; j < guards.length; j++) {
List freeVars = (List) guards[j]
.getAttribute(AttributeKeys.KEYFREEVAR);