This volume contains papers presented at the Fifth Taniguchi Symposium on the Theory of Condensed Matter, which was held between 2-5 November, 1982, at Shimoda, Japan. The topic of the Symposium was "Topological Disorder in Condensed Matter. " The objective of the Taniguchi Symposium is to encourage activity in those fields of research not in the limelight at the moment but regarded as very promising, such as our theme. Topological disorder refers to the dis order in the positions and connectivities of atoms in amorphous solids and liquids. The development of the physiCS of topologically disorderd systems, though extremely important fundamentally and for application purposes, falls far behind compared to that of other kinds of disorderd systems because the structure characterization of topologically disordered systems is still at a rather primitive stage. The structure characterization is the key to com prehensive understanding of physical properties of any material. Recently, several new attempts at structural analyses have been reported. Encouraged by this fact, our motivation in organizing the symposium was to investigate the possibilities of theoretical approaches to open a breakthrough in the present research situation on this subject. A rough sketch of the problem is made in the Introduction to give the readers a general outline of the subject. Part I is devoted to several at tempts to synthesize and characterize topological disorder more or less by analytical means."

The Kyoto Summer Institute 1980 (KSI '80), devoted to "Fundamental Physics of Amorphous Semiconductors," was held at Research Institute for Fundamental Physics (RIFP), Kyoto University, from 8-11 September, 1980. The KSI '80 was the successor of the preceding Institutes which were held in July 1978 on "Particle Physics and Accelerator Projects" and in September 1979 on "Physics of Low-Dimensional Systems." The KSI '80 was attended by 200 participants, of which 36 were from abroad: Canada, France, Korea, Poland, U.K., U.S.A, U.S.S.R., and the Federal Republic of Germany. The KSI '80 was organized by RIFP and directed by the Amorphous Semicon ductor group in Japan. A few years ago, we started to organize an interna tional meeting on amorphous semiconductors' as a satell ite meeting of the International Conference on "Physics of Semiconductors" held on September 1-5, 1980 in Kyoto. We later decided to hold the meeting in the form of the Kyoto Summer Institute. The Kyoto Summer Institute is aimed to be something between a school and a conference. Accordingly, the object of the KSI '80 was to provide a series of invited lectures and informal seminars on fundamental physics of amorphous semiconductors. No contributed paper was accepted, but seminars were open."

This book originally appeared in Japanese in 1973 in the Iwanami Series of Fundamental Physics supervised by Professor Hideki Yukawa and pub lished by Iwanami-Shoten. A revised second edition was published in 1978. The task we set ourselves was to grasp the properties of matter as a whole in a unified scheme and to present a general view of matter incor porating the results of modern physics. To achieve this goal we have tried to explore the laws which describe the structure of macroscopic matter, namely, to ask in what kinds of phy sical states matter can, in principle, exist and why. Thus, using the meth ods of statistical physics and quantum mechanics, we have tried to syste matically describe the properties of matter from a unified point of view. Of course, we do not believe that such a standpoint can give an exhaus tive description of condensed matter. One of the important viewpoints which obviously is omitted in such a unified approach is the historical one, which follows the development of physics in the course of time."