The book offers a novel approach to the study of the complex dynamics of cities. It is based on (1) Synergetics as a science of cooperation and selforganization, (2) information theory including semantic and pragmatic aspects, and optimization principles, (3) a theory of steady state maintenance, and of (4) phase transition, i.e. qualitative changes of structure or behavior. From this novel theoretical vantage point, the book addresses particularly three issues that stand at the core of current discourse on cities: Urban Scaling, Smart Cities and City Planning. An important consequence of "the 21st century as the age of cities", is that the study of cities currently attracts scientists from a variety of disciplines, ranging from physics, mathematics and computer science, through urban studies, architecture, planning and human geography, to economics, psychology, sociology, public administration and more. The book is thus likely to attract scholars, researchers and students of these research domains, of complexity theories of cities, as well as of general complexity theory. In addition, it is directed also to practitioners of urbanism, city planning and urban design.

The book offers a novel approach to the study of the complex dynamics of cities. It is based on (1) Synergetics as a science of cooperation and selforganization, (2) information theory including semantic and pragmatic aspects, and optimization principles, (3) a theory of steady state maintenance, and of (4) phase transition, i.e. qualitative changes of structure or behavior. From this novel theoretical vantage point, the book addresses particularly three issues that stand at the core of current discourse on cities: Urban Scaling, Smart Cities and City Planning. An important consequence of "the 21st century as the age of cities", is that the study of cities currently attracts scientists from a variety of disciplines, ranging from physics, mathematics and computer science, through urban studies, architecture, planning and human geography, to economics, psychology, sociology, public administration and more. The book is thus likely to attract scholars, researchers and students of these research domains, of complexity theories of cities, as well as of general complexity theory. In addition, it is directed also to practitioners of urbanism, city planning and urban design.

These proceedings contain the invited lectures presented at the International Sym- posium on Synergetics at Schloss Elmau in April, 1982. This symposium marked the th 10 anniversary of symposia on synergetics, the first of which was held at Schloss Elmau in 1972. As is now weIl known, these symposia are devoted to the study of the formation of structures in physical systems far from thermal equilibrium, as weIl as in nonphysical systems such as those in biology and sociology. While the first proceedings were published by Teubner Publishing Company in 1973 and the second by North Holland Publishing Company in 1974, the subsequent proceed- ings have been published in the Springer Series in Synergetics. I believe that these proceedings give a quite faithful picture of the developments in this new interdisciplinary field over the past decade. As H.J. Queisser recently noted, the prefix "non", which is used quite frequent- ly in modern scientific literature in words such as "nonequilibrium", "nonlinear", etc., indicates a new development in scientific thinking. Indeed, this new develop- ment was anticipated and given a framework in the introduction of "synergetics" more than a decade ago.

This book presents the invited lectures given at the International Symposium on Synergetics of Cognition held at SchloB Elmau, Bavaria (Fed. Rep. of Germany), June 4-8, 1989. The understanding of the processes underlying cognition is certainly one of the most challenging and difficult problems confronting the human mind. It is an enterprise that requires the cooperation of scientists from fields ranging from the neurosciences and psychology through biology to the computer sciences, physics and mathematics. The papers included in this volume reflect this joint effort. As will be evident, there is a remarkable convergence of ideas stemming from various fields, for instance, the earlier ideas on Gestalt theory celebrate a come back and remarkable analogies are being established with modem concepts of self-organization as dealt with in the interdisciplinary field of synergetics. The individual topics range from the "microscopic level," where new exciting results on specific oscillations of neural activity are reported, to computer simulations of perception, and finally psychological experiments at the "macroscopic level." We hope that this book will convey to its readers the same enthusiasm that was felt by the participants of the symposium. We wish to thank Mrs. U. Funke for the excellent organisation of the sym posium, and the Volkswagen-Stiftung, Hannover, for its financial support. We are furthermore grateful to Christoph Stadler and Zora Franko for their help in com piling the name and subject indexes. Finally we wish to thank Springer-Verlag, in particular Dr. Angela Lahee, for the excellent cooperation."

Neural and Synergetic Computers deals with basic aspect of this rapidly developing field. Several contributions are devoted to the application of basic concepts of synergetics and dynamic systems theory to the constructionof neural computers. Further topics include statistical approaches to neural computers and their design (for example by sparse coding), perception motor control, and new types of spatial multistability in lasers.

Nonlinear dynamics is now recognized as playing a crucial role in a wide variety of disciplines. But what is only just beginning is the important process of cross fertilization and transfer of knowledge and expertise from one area to another. This book is intended to promote this process which will undoubtedly contribute greatly to furthering our understanding of complex systems. Contributions are provided by leading experts from the areas of sociology, cognitive science, chemistry, physiology, ecology, economics, neural networks and physics.

Over the past years the field of synergetics has been mushrooming. An ever increasing number of scientific papers are published on the subject, and numerous conferences all over the world are devoted to it. Depending on the particular aspects of synergetics being treated, these conferences can have such varied titles as "Nonequilibrium Nonlinear Statistical Physics," "Self-Organization," "Chaos and Order," and others. Many professors and students have expressed the view that the present book provides a good introduction to this new field. This is also reflected by the fact that it has been translated into Russian, Japanese, Chinese, German, and other languages, and that the second edition has also sold out. I am taking the third edition as an opportunity to cover some important recent developments and to make the book still more readable. First, I have largely revised the section on self-organization in continuously extended media and entirely rewritten the section on the Benard instability. Sec ond, because the methods of synergetics are penetrating such fields as eco nomics, I have included an economic model on the transition from full employ ment to underemployment in which I use the concept of nonequilibrium phase transitions developed elsewhere in the book. Third, because a great many papers are currently devoted to the fascinating problem of chaotic motion, I have added a section on discrete maps. These maps are widely used in such problems, and can reveal period-doubling bifurcations, intermittency, and chaos."

This text on the interdisciplinary field of synergetics will be of interest to students and scientists in physics, chemistry, mathematics, biology, electrical, civil and mechanical engineering, and other fields. It continues the outline of basic con cepts and methods presented in my book Synergetics. An Introduction, which has by now appeared in English, Russian, J apanese, Chinese, and German. I have written the present book in such a way that most of it can be read in dependently of my previous book, though occasionally some knowledge of that book might be useful. But why do these books address such a wide audience? Why are instabilities such a common feature, and what do devices and self-organizing systems have in common? Self-organizing systems acquire their structures or functions without specific interference from outside. The differentiation of cells in biology, and the process of evolution are both examples of self-organization. Devices such as the electronic oscillators used in radio transmitters, on the other hand, are man made. But we often forget that in many cases devices function by means of pro cesses which are also based on self-organization. In an electronic oscillator the motion of electrons becomes coherent without any coherent driving force from the outside; the device is constructed in such a way as to permit specific collective motions of the electrons. Quite evidently the dividing line between self-organiz ing systems and man-made devices is not at all rigid."

It is increasingly being recognized that the experimental and theoretical study of the complex system brain requires the cooperation of many disciplines, in cluding biology, medicine, physics, chemistry, mathematics, computer science, linguistics, and others. In this way brain research has become a truly interdis ciplinary endeavor. Indeed, the most important progress is quite often made when different disciplines cooperate. Thus it becomes necessary for scientists to look across the fence surrounding their disciplines. The present book is written precisely in this spirit. It addresses graduate students, professors and scientists in a variety of fields, such as biology, medicine and physics. Be yond its mathematical representation the book gives ample space to verbal and pictorial descriptions of the main and, as I believe, fundamental new insights, so that it will be of interest to a general readership, too. I use this opportunity to thank my former students, some of whom are my present co-workers, for their cooperation over many years. Among them I wish to mention in particular M. Bestehorn, L. Borland, H. Bunz, A. Daf fertshofer, T. Ditzinger, E. Fischer, A. Fuchs, R. Haas, R. Honlinger, V. Jirsa, M. Neufeld, M. Ossig, D. Reimann, M. Schanz, G. Schoner, P. Tass, C. Uhl. My particular thanks go to R. Friedrich and A. Wunderlin for their constant help in many respects. Stimulating discussions with a number of colleagues from a variety of fields are also highly appreciated.

This fourth edition contains a few additional figures. Otherwise only typographical er rors have been removed. The final chapter on Fundamentals of the Quantum Theory of Chemical Bonding is continued in an extended way in the textbook Molecular Physics and Elements of Quantum Chemistry by the same authors. This book contains, in particular, a profound presentation of group theory as applied to atoms and molecules. Furthermore, the in teraction between atoms and molecules and light is treated in detail. We thank again Springer-Verlag, in particular Dr. H.1. Kblsch and Mr. C.-D. Bachem for their excellent cooperation as always, and Prof. W. D. Brewer for his con tinuous support in translating our German text. Stuttgart, February 1994 H. Haken H. C. Wolf Preface to the Third Edition The second edition of this book again enjoyed a very positive reception from both uni versity teachers and students. In this edition we have removed all of the typographical errors that came to our attention. In order to keep the book as current as possible, new developments in the direct observation of individual atoms in electromagnetic traps (Paul traps) and of atoms in molecules on solid surfaces using the scanning tunnel microscope have been added to this edition.

Synergetics may be considered as an interdisciplinary effort dealing with the gene ral problem of how science can cope with complex systems. The preceding symposia on synergetics were devoted to systems of physics, chemistry and partly also biolo gy and sociology. It was possible to develop adequate concepts to describe and even to calculate evolving macroscopic spatial, temporal, and functional structures which emerge through self-organization of the individual parts of the systems under con sideration. This book contains the invited papers presented at the Symposium on the Synerge tics of the brain, Schloss Elmau, Bavaria, May 2 to 7, 1983. The inclusion of this topic in the synergetics enterprise represents a big step towards a treatment of complex systems. Most probably the human brain is the most complex system we know of. As the organizers believe, this symposium provides the reader with a good cross section of experimental results and theoretical approaches to cope with the complex problems of structure and function of the brain. It was generally felt that such a joint meeting between experimentalists and theoreticians is of great importance for future development of this field. Modern experimental methods, e. g. multielectrode derivations allow or will allow us, in short, to collect huge amounts of data. Simi larly high-speed computers will flood us with an enormous number of outputs once the basic model equations have been chosen."

A great deal of the success of science has rested on its specific methods. One of which has been to start with the study of simple phenomena such as that of falling bodies, or to decompose systems into parts with well-defined properties simpler than those of the total system. In our time there is a growing awareness that in many cases of great practical or scientific interest, such as economics or the hu man brain, we have to deal with truly complex systems which cannot be decomposed into their parts without losing crucial properties of the total system. In addi tion, complex systems have many facets and can be looked at from many points of view. Whenever a complicated problem arises, some scientists or other people are ready to invent lots of beautiful words, or to quote Goethe "denn immer wo Begriffe feh len, dort stellt ein Wort zur rechten Zeit sich ein" ("whenever concepts are lack king, a word appears at the right time"). Quite often such a procedure gives not only the layman but also scientists working in fields different from that of the in ventor of these new words the impression that this problem has been solved, and I am occasionally shocked to see how influential this kind of "linguistics" has become.

This book was written, to a not inconsiderable degree, on the basis of the course "The Problems of Modern Biophysics" which the author gives to the students and postgraduates of the Biophysical Department at Moscow University School of Physics. It is meant for those who have a sufficiently good background in physics as well as in biology. I have tried to make this book intelligible to a broader circle of readers, i.e., to physicists not competent enough in biology, and to biologists not competent enough in physics. I hope that I have succeeded. This book is neither a textbook nor a systematic account of a field of science. I think that in modern biological physics, i.e., in the branch of biology where people having fundamental physical or physico-chemical education are working, so many specific answers have been recently obtained that it is now just the right time to ask at least several questions of a general nature. The aim of this book is to formulate such questions though their choice is, to a considerable degree, determined by the authors preferences and interests.

This volume contains the talks presented at the International Symposium on Electronic Excitations and Interaction Processes in Organic Molecular Aggre gates which was held at Schloss Elmau, Bavaria, Germany from June 5 to June 10, 1983. In the recent years the investigation of organic materials has developed rapidly and has led to the construction of materials with interesting proper ties. The discovery of highly conducting and superconducting organic materials is definitely one of the reasons for the enormous increase in research acti vity in this field. Interesting applications have been realized or seem pos sible, such as the application of organic materials in electrophotography. The conductivity of organic polymers may be varied within a large range by doping and such materials have been used to construct an organic battery. Some time ago it was suggested that organic glasses and polymers could be used as stor age materials in computer technology. With the development of preparation tech niques and modern methods of investigation, for example, high resolution and picosecond spectroscopy, a large amount of experimental data is available not only for the conducting materials but also for organic semiconductors and in sulators. With this rapid accumulation of experimental material the microscopic theoretical understanding could not keep pace."

The chapters in this book centre around one main theme, the concept of the machine and its use as metaphor in a variety of contexts. This concept is deeply rooted in western culture and is frequently used to interpret complex systems in nature and society. With the advent of electronic computers, the machine metaphor applied to thinking and the brain has becOIne even more pertinent. The idea of a machine has changed over time. In this book these transformations are made trans parent, various aspects of the machine metaphor are discussed and limitations and pitfalls of the metaphor are elaborated. The chapters are written in a non-technical fashion and are accessible to a large readership of scientists and also laymen interested in the scientific per spectives and logical foundations of the machine concept that has been so influential in western thinking. The idea of the book has its origin in a workshop held at the Sci entific Station in Abisko, Sweden, in May 1990, where several of the present authors participated. The meeting was organized and spon sored by the Swedish Council for Planning and Coordination of Re search (FRN). Since 1983, the FRN has actively promoted a series of such annual events at Abisko, all of which have been devoted to the exploration of various aspects of complex systems and their evolution.

This book contains the invited papers presented at an international sympo sium held at Schloss Elmau, Bavaria (FRG), May 4-9, 1987. Leading experts from neurobiology, medicine, physics, and the computer sciences joined to gether to present and discuss their most recent results. A particular example of the natural computational systems discussed is the visual system of man and animals. A bridge between neural networks and physical systems is provided by spin glass models of neural networks, which were also treated. Concrete realizations of new kinds of devices in microelectronics were among the further topics, as were general problems on the calculation of chaotic orbits. In this way these proceedings present a number of quite recent ap proaches to problems which are of great current interest in fields concerned with computational systems. Bringing together scientists from neurobiology, physics, and the computer sciences has been one of the main aims of the synergetics enterprise, and in particular of its international symposia, from the very beginning. For exam ple, its first meeting held in 1972 at Schloss Elmau included, among others, papers by R. Landauer and J. W. F. Woo on cooperative phenomena in data processing, by W. Reichardt on mechanisms of pattern recognition by the visual system of insects, by B. Julesz on stereoscopic depth perception, and by H. R. Wilson on cooperative phenomena in a homogeneous cortical tissue model. Whole meetings and the corresponding proceedings were devoted to these problems, e. g.

This book contains the invited papers of an international symposium on synergetics; which was held at Schlol3 Elmau, Bavaria, FRG, April 27 to May 1, 1981. At our previous meetings on synergetics the self-organized formation of structures in quite different disciplines stood in the foreground of our interest. More recently it has turned out that phenomena characterized by the word "chaos" appear in various disciplines, and again far-reaching analogies in the behavior of quite different systems become visible. Therefore this meeting was devoted not only to problems connected with the occurrence of ordered structures but also to most recent results obtained in the study of chaotic motion. In the strict mathematical sense we are dealing here with deterministic chaos, i. e. , irregular motion described by deter ministic equations. While in this relatively young fieJd of research computer ex periments and computer simulations predominated in the past, there now seems to be a change of trend, namely to study certain regular features of chaos by analytical metbods. I think considerable progress has been achieved in this respect quite recently. This theoretical work is paralleled by a number of very beautiful experi ments in different fields, e. g. , fluid dynamics, solid-state physics, and chemistry. For the first time at this kind of meeting we have included plasma physics, which presents a number of most fascinating problems with respect to instabilities, formation of structures, and related phenomena.

Rhythms are a basic phenomenon in all physiological systems. They cover an enormous range of frequencies with periods from the order of milliseconds up to some years. They are described by many disciplines and are investigated usually in the context of the physiology of the respective function or organ. The importance given to the research on rhythmicity is quite different in different systems. In some cases where the functional significance is obvious rhythms are at the center of interest, as in the case of respiration or locomotion. In other fields they are considered more or less as interesting epiphenomena or at best as indicators without essential functional significance, as in the case of cardiovascular or EEG rhythms. Recently the study of physiological rhythms has attracted growing interest in several fields, especially with respect to rhythm research in humans and its rapidly spreading applications in basic behavioral research, and as a diagnostic tool in clinical medicine. This development was favored by two methodological and conceptual ad vances: on the one hand, the availability of non-invasive methods of continu ous recording of physiological parameters and their computer-assisted evaluation, and on the other, the rapid development of theoretical analyses, for example, the understanding of dynamic systems, the generation of coordinated macroscopic pro cesses in systems comprising many single elements, and the mathematical tools for treating nonlinear oscillators and their mutual coupling.

This book contains the manuscripts of the papers delivered at the International Sym posium on Synergetics held at SchloB Elmau, Bavaria, Germany, from April 30 until May 5, 1979. This conference followed several previous ones (Elmau 1972, Sicily 1974, Elmau 1977). This time the subject of the symposium was "pattern formation by dynam ic systems and pattern recognition." The meeting brought together scientists from such diverse fields as mathematics, physics, chemistry, biology, history as well as experts in the fields of pattern recognition and associative memory. When I started this type of conference in 1972 it appeared to be a daring enter prise. Indeed, we began to explore virgin land of science: the systematic study of cooperative effects in physical systems far from equi ibrium and in other disciplines. Though these meetings were attended by scientists from quite different disciplines, a basic concept and even a common language were found from the very beginning. The idea that there exist profound analogies in the behaviour of large classes of complex systems, though the systems themselves may be quite different, proved to be most fruitful. I was delighted to see that over the past one or two years quite similar conferences were now held in various places allover the world. The inclusion of prob lems of pattern recognition at the present meeting is a novel feature, however."

This volume contains most of the invited papers presented at the International Work shop on Synergetics, Schloss E1mau, Bavaria, May 2 to.May 7, 1977. This workshop fol lowed an International Symposium on SynergetiGS at Schloss E1mau, 1972, and an Inter national SUl11l1erschoo1 at Erice, Sicily, 1974. Synergetics is a rather new field of interdisciplinary research which studies the self-organized behavior of systems leading to the formation of structures and func tionings. Indeed the whole universe seems to be organized, with pronounced structures starting from spiral galaxies down to living cells. Furthermore, very many of the most interesting phenomena occur in systems which are far from thermal equilibrium. Synergetics in its present form focusses its attention on those phenomena where dra matic changes occur on a macroscopic scale. Here indeed Synergetics was able to re veal profound analogies between systems in different disciplines ranging from physics to sociology. This volume contains contributions from various fields but the reader will easily discover their cOl11J1on goal. Not only in the natural sciences but also in ecology, sociology, and economy, man is confronted with the problems of complex sys tems. The principles and analogies unearthed by Synergetics will certainly be very he1pfu to cope with such difficult problems. I use this opportunity to thank the Vo1kswagenwerk Foundation for its support of the project Synergetics and in particular for sponsoring the International Workshop on Synergetics."

This book presents a novel approach to neural nets and thus offers a genuine alternative to the hitherto known neuro-computers. The new edition includes a section on transformation properties of the equations of the synergetic computer and on the invariance properties of the order parameter equations. Further additions are a new section on stereopsis and recent developments in the use of pulse-coupled neural nets for pattern recognition.

This textbook introduces the molecular and quantum chemistry needed to understand the physical properties of molecules and their chemical bonds. It follows the authors' earlier textbook "The Physics of Atoms and Quanta" and presents both experimental and theoretical fundamentals for students in physics and physical and theoretical chemistry. The new edition treats new developments in areas such as high-resolution two-photon spectroscopy, ultrashort pulse spectroscopy, photoelectron spectroscopy, optical investigation of single molecules in condensed phase, electroluminescence, and light-emitting diodes.

The widespread interest this book has found among professors, scientists and stu dents working in a variety of fields has made a new edition necessary. I have used this opportunity to add three new chapters on recent developments. One of the most fascinating fields of modern science is cognitive science which has become a meet ing place of many disciplines ranging from mathematics over physics and computer science to psychology. Here, one of the important links between these fields is the concept of information which, however, appears in various disguises, be it as Shan non information or as semantic information (or as something still different). So far, meaning seemed to be exorcised from Shannon information, whereas meaning plays a central role in semantic (or as it is sometimes called "pragmatic") information. In the new chapter 13 it will be shown, however, that there is an important interplay between Shannon and semantic information and that, in particular, the latter plays a decisive role in the fixation of Shannon information and, in cognitive processes, al lows a drastic reduction of that information. A second, equally fascinating and rapidly developing field for mathematicians, computer scientists and physicists is quantum information and quantum computa tion. The inclusion of these topics is a must for any modern treatise dealing with in formation. It becomes more and more evident that the abstract concept of informa tion is inseparably tied up with its realizations in the physical world."

This book presents a novel approach to neural nets and thus offers a genuine alternative to the hitherto known neuro-computers. The new edition includes a section on transformation properties of the equations of the synergetic computer and on the invariance properties of the order parameter equations. Further additions are a new section on stereopsis and recent developments in the use of pulse-coupled neural nets for pattern recognition.

This textbook introduces the molecular and quantum chemistry needed to understand the physical properties of molecules and their chemical bonds. It follows the authors' earlier textbook "The Physics of Atoms and Quanta" and presents both experimental and theoretical fundamentals for students in physics and physical and theoretical chemistry. The new edition treats new developments in areas such as high-resolution two-photon spectroscopy, ultrashort pulse spectroscopy, photoelectron spectroscopy, optical investigation of single molecules in condensed phase, electroluminescence, and light-emitting diodes.