class Graph implements Serializable {

	public Node<T> findRootNode(Node<T> startNode) {
		List<Node<T>> ascendingNodes = getAscendingNodes(startNode);
		for (Node<T> node : ascendingNodes) {
			if(rootNodes.contains(node))
				return node;
		}
		return null;
	}

	public  Graph();

}