SOLUTIONS OF THE YANG-BAXTER EQUATION FOR ISOTROPIC QUANTUM SPIN CHAINS - COMMENT

We comment on a recent paper by Kennedy (J. Phys. A: Math. Gen. 25 (1992) 2809) in which a systematic search for integrable spin-S su(2)-invariant quantum chains for S less-than-or-equal-to 6 revealed four spin-S families of integrable chains along with an additional integrable chain at S = 3. We identify these su(2)-invariant chains with known G-invariant R-matrices, where G is a simple Lie algebra, and give arguments that Kennedy's results may well constitute the complete classification of integrable spin-S su(2)-invariant chains.