Physics of the Ideal Semion Gas: Spinons and Quantum Symmetries of the   Integrable Haldane-Shastry Spin Chain
  Various aspects of the Haldane-Shastry spin chain with 1/r^2 exchange, and its various generalizations, are reviewed, with emphasis on its Yangian quantum group structure, and the interpretation of the model as the generalization of an ideal gas (of ``spinons'') to the case of fractional statistics. Some recent results on its dynamical correlation function are discussed, and conjectured extensions of these remarkably simple results to the $SU(n)$ model, and to the related Calogero-Sutherland model with integer coupling constant, are presented. (Talk presented at the 16th. Taniguchi Symposium, Kashikojima, Japan, October 26-29, 1993) 
F. D. M. Haldane