This volume contains papers presented at the Twelfth Taniguchi Symposium on the Theory of Condensed Matter, which was held at Kashikojima (in Ise Shima National Park), Japan, November 14-19, 1989. The general purpose of the Taniguchi Symposia is to encourage important developing, rather than established, fields in condensed matter theory. The topic of the present sym posium, Quasicrystais, is quite typical. In 1984, Shechtman, Blech, Gratias and Cahn discovered the icosahedral symmetry of a diffraction pattern and Levine and Steinhardt independently presented the notion of quasicrystals....

In Japanese culture the concept of katachi has special significance, connoting relationships and connectedness. Although katachi cannot be translated precisely, it corresponds most closely to "form," "shape," "pattern," or "Gestalt". The contemporary study of katachi is interdisciplinary and encompasses virtually all scientific and aesthetic endeavors. Katachi research seeks to bridge the gap between cultures - whether the "two cultures" of C.P. Snow or the contrasting cultures of East and West. To help achieve this aim and to foster international cooperation, the interdisciplinary symposium...