@Override
	public void dumpPrecedenceGraph()
	{
		Element precGraphElement = (Element) dumpTop.appendChild(document.createElement("precgraph"));
		for(Terminal t : grammar.getT())
		{
			if(!grammar.getPrecedenceRelationsGraph().hasVertex(t)) continue;
			Element vertexElement = (Element) precGraphElement.appendChild(document.createElement("vertex"));
			vertexElement.setAttribute("tag","t" + numbering.get(t));
			for(Terminal u : grammar.getT())
			{
				if(grammar.getPrecedenceRelationsGraph().hasVertex(u) &&
				   grammar.getPrecedenceRelationsGraph().hasEdge(t,u))
				{
					Element edgeElement = (Element) precGraphElement.appendChild(document.createElement("edge"));
					edgeElement.setAttribute("submits","t" + numbering.get(t));
					edgeElement.setAttribute("dominates","t" + numbering.get(u));
				}
			}
		}
	}