@SuppressWarnings("unused")
	private boolean canReachForwards( Node from, Node to, int version )
	{
		while ( from != null && from != to )
		{
			Arc a = from.pickOutgoingArc( version );
			if ( a.versions.cardinality() != 1 )
				return false;
			if ( from != null )
				from = a.to;
		}
		return from == to;
	}