Abstract
It is argued that a recent article by Z.-D. Zhang is in error and violates well-known theorems.
Acknowledgement
The author is supported by NSF grant PHY 07-58139.
Notes
Notes
1. In the proceedings he is called M. Maddox, with M for Monsieur (Mister in French).
2. I omit here the extra U-factors in the terms ) resulting from periodic boundary conditions Citation11, which are also present in Citation1. With open boundary conditions there are no such U's.
3. Lou and Wu Citation10 correctly apply an equation equivalent to (3) (using Z for σ x and X for −σ z ). However, they go wrong after (77) in Citation10, as they assume too much commutativity for the factors of P. I thank Dr. Zhang for bringing Citation10 to my attention.