Comments on renormalization group series

In previous articles by Nauenberg and by Niemeijer and Ruijgrok, the renormalization group approach has been used to obtain series expansions for the free energies of certain one- dimensional spin systems. We investigate here the question of whether this method provides a fundamentally new way of approximating the largest eigenvalue of a transfer matrix or kernel. For the models mentioned above, this is not the case. The partial sums of the series are essentially equivalent to the free energies of a sequence of finite models of increasing size.