This volume on mathematical control theory contains high quality articles covering the broad range of this field. The internationally renowned authors provide an overview of many different aspects of control theory, offering a historical perspective while bringing the reader up to the very forefront of current research.

As the Proceedings of the 1984 Canadian Mathematical Society's Summer Seminar, this book focuses on some advances in the theory of semisimple Lie algebras and some direct outgrowths of that theory. The following papers are of particular interest: an important survey article by R. Block and R. Wilson on restricted simple Lie algebras, a survey of universal enveloping algebras of semisimple Lie algebras by W. Borho, a course on Kac-Moody Lie algebras by I. G. Macdonald with an extensive bibliography of this field by Georgia Benkart, and a course on formal groups by M. Hazewinkel. Because of the expository surveys and courses, the book will be especially useful to graduate students in Lie theory, as well as to researchers in the field.

This book contains the text of the plenary lectures and the mini-courses of the European Control Conference (ECC'93) held in Groningen, the Netherlands, June 2S-July 1, 1993. However, the book is not your usu al conference proceedings. Instead, the authors took this occasion to take a broad overview of the field of control and discuss its development both from a theoretical as well as from an engineering perpective. The first essay is by the key-note speaker ofthe conference, A.G.J. Mac Farlane. It consists of a non-technical discussion of information processing and knowledge acquisition as the key features of control engineering tech nology. The next six articles are accounts of the plenary addresses. The contribution by R.W. Brockett concerns a mathematical framework for modelling motion control, a central question in robotics and vision. In the paper by M. Morari the engineering and the economic relevance of chemical process control are considered, in particular statistical quality control and the control of systems with constraints. The article by A.C.P.M. Backx is written from an industrial perspec tive. The author is director of an engineering consulting firm involved in the design of industrial control equipment. Specifically, the possibility of obtaining high performance and reliable controllers by modelling, identifi cation, and optimizing industrial processes is discussed.

Turbulence is the lIDst natural nDde of fluid lIDtion, and has been the subject of scientific study for all Dst a century. During this period, various ideas and techniques have evolved to nDdel turbulence. Following Saffman, these theoretical approaches can be broadly divided into four overlapping categories -- (1) analytical lIDdelling, (2) physical lIDdelling, (3) phenomenologicalllDdelling, and (4) nurerical lIDdelling. With the purpose of stmtnarizing our =ent understanding of these theoretical approaches to turbulence, recognized leaders (fluid dynamicists, mathematicians and physicists) in the field were invited to participate in a formal workshop during October 10-12, 1984, sponsored by The Institute for CooIputer Applications in Science and Engineering and NASA Langley Research Center. Kraiciman, McCcxnb, Pouquet and Spiegel represented the category of analytical nDdelling, while Landahl and Saffman represented physical lIDdelling. The contributions of Latmder and Spalding were in the category of phenanenological lIDdelling, and those of Ferziger and Reynolds in the area of nurericalllDdelling. Aref, Cholet, Lumley, Moin, Pope and Temam served on the panel discussions. With the care and cooperation of the participants, the workshop achieved its purpose, and we believe that its proceedings published in this vol\. llre has lasting scientific value. The tone of the workshop was set by two introductory talks by Bushnell and ChaImm. Buslmell presented the engineering viewpoint while Chapman reviewed from a historical perspective developments in the study of turbulence. The remaining talks dealt with specific aspects of the theoretical approaches to fluid turbulence.