VMap( short v, Vector<Pair> pairs )
	{
		HashMap<Pair,Pair> vMap = new HashMap<Pair,Pair>();
		if ( pairs.size() > 1 )
		{
			Pair last = null;
			for ( int i=0;i<pairs.size();i++ )
			{
				// examine all the v-pairs
				Pair p = pairs.get( i );
				if ( p.contains(v) )
				{
					if ( last == null )
						continue;
					else if ( last.isChild() && p.isChild() )
						vMap.put( last, p );
					else if ( last.isParent() && p.isParent() )
						vMap.put( last, p );
					last = p;
				}
			}
		}
	}