/**
  * Create a dependency between two events.
  *
  * @param parentEvent The parent event.
  * @param childEvent The child event.
  */
 public void createDependency(BayesianEvent parentEvent, BayesianEvent childEvent) {
   // does the dependency exist?
   if (!hasDependency(parentEvent, childEvent)) {
     // create the dependency
     parentEvent.addChild(childEvent);
     childEvent.addParent(parentEvent);
   }
 }
 /**
  * Create a dependency between a parent and multiple children.
  *
  * @param parentEvent The parent event.
  * @param children The child events.
  */
 public void createDependency(BayesianEvent parentEvent, BayesianEvent... children) {
   for (BayesianEvent childEvent : children) {
     parentEvent.addChild(childEvent);
     childEvent.addParent(parentEvent);
   }
 }