This book contains lectures given at the Institute for Scientific Interchange (I.S.I., Turin) in 1983 - 1984 on the exact solution of the 8-vertex and related models and extensions of the Baxter model to 3 dimensions.

This book contains lectures given at the Institute for Scientific Interchange (I.S.I., Turin) in 1983 - 1984 on the exact solution of the 8-vertex and related models and extensions of the Baxter model to 3 dimensions.

An international workshop on Elementary Excitations and Fluctuations in Magnetic Systems was held in Turin for five days beginning 25 May, 1987. The workshop followed much the same format as the one with the same title held in San Miniato in 1984 (proceedings: Springer Series in-Solid-State Sciences, Vol. 54), that most participants contributed talks and provided papers for the proceedings. While many of the participants had attended the first workshop, 15 of the 40 invited review papers were presented by scientists who had not. The majority of the talks reported theoretical work concerned with the introduction of new techniques. However, experimental work was also well represented, not least because many of the reported theoretical studies were motivated by experimental findings, and a highlight of the workshop was an extremely stimulating session devoted to recent neutron scattering measure- ments, on various systems, that exploited polarization analysis. The fine venue of the workshop, Villa Gualino, with its excellent facili- ties and spacious accommodation, helped to produce a delightful relaxed and friendly atmosphere. For the use of Villa Gualino and significant financial support we are indebted to our host organization, the Institute for Scien- tific Interchange (lSI). Additional financial support came from the Consiglio Nazionale delle Ricerche (CNR), Centro Interuniversitario di Struttura della Material del Ministero della Pubblica Istruzione (CISM-MPI) and Gruppo Nazionale di Struttura della Materia (GNSM-CNR).

This book consists of a set of lecture notes on graduate courses in Analytical Mechanics and Statistical Mechanics which the author successively gave at the University of Miami, and at the University and Polytechnic of Turin over the past decade. The book centers on the idea that stochasticity can come out of nonlinearities even in the case of a few degrees of freedom, and on how this bears on the known methods of classical statistical mechanics and its link with thermodynamics.