boolean hasChildInVersion( short version )
	{
		if ( children != null )
		{
			ListIterator<Arc> iter = children.listIterator(0);
			while ( iter.hasNext() )
			{
				Arc child = iter.next();
				if ( child.versions.nextSetBit(version)==version )
					return true;
			}
			return false;
		}
		else
			return false;
	}