static void checkForCycle( SimpleQueue<Node> list, Arc a, int limit )
		throws MVDException
	{
		if ( list.contains(a.to) )
			throw new MVDException("Cycle: node"+a.to.nodeId+" already encountered");
		else if ( limit > 0 )
		{
			ListIterator<Arc> iter = a.to.outgoingArcs();
			while ( iter.hasNext() )
			{
				Arc b = iter.next();
				//System.out.println(b.toString() );
				list.add( a.to );
				checkForCycle( list, b, limit-1 );
			}
		}
	}