setSingleHeadedConstraint(true);
root = new Root();
root.setBelongsToGraph(this);
graphEdges = new TreeSet<Edge>();
edgePool = new ObjectPoolList<Edge>() {
protected Edge create() { return new GraphEdge(); }
public void resetObject(Edge o) throws MaltChainedException { o.clear(); }
};
nonTerminalNodes = new TreeMap<Integer,NonTerminal>();
nonTerminalPool = new ObjectPoolList<NonTerminal>() {