Essays in Group Theory contains five papers on topics of current interest which were presented in a seminar at MSRI, Berkeley in June, 1985. Special mention should be given to Gromov`s paper, one of the most significant in the field in the last decade. It develops the theory of hyperbolic groups to include a version of small cancellation theory sufficiently powerful to recover deep results of Ol'shanskii and Rips. Each of the remaining papers, by Baumslag and Shalen, Gersten, Shalen, and Stallings contains gems. For example, the reader will delight in Stallings' explicit construction of free actions of orientable surface groups on R-trees. Gersten's paper lays the foundations for a theory of equations over groups and contains a very quick solution to conjugacy problem for a class of hyperbolic groups. Shalen's article reviews the rapidly expanding theory of group actions on R-trees and the Baumslag-Shalen article uses modular representation theory to establish properties of presentations whose relators are pth-powers.

“A refreshing collection of superb mathematical essays . . . from choosing up sides to choosing names, the topics are intriguingly nonstandard . . . First-rate.” —John Allen Paulos, author of Innumeracy A science and technology journalist and essayist whose work has appeared in multiple anthologies, Brian Hayes now presents a selection of his most memorable pieces—including the National Magazine Award–winning “Clock of Ages”—in this enjoyable volume. In addition, Hayes embellishes the collection with an overall scene-setting preface, reconfigured illustrations, and a refreshingly self-critical “Afterthoughts” section appended to each essay. “You don’t have to be a geek to appreciate Hayes’s lively, self-effacing style . . . The first essay explains how clockmakers developed the gears and linkages that enabled fabled medieval clocks to reach remarkable accuracy, as well as predict the day Easter would fall on. Other essays celebrate the notion of random numbers and why they are so hard to achieve. Numerical analysis also plays a role in economic models based on the kinetic theory of gases or simplified markets involving iterations of buying and selling. Hayes goes on to explain how statistics have been applied to compute which quarrels—from interpersonal to world wars—are the deadliest (surprising results here) . . . Challenging but rewarding for anyone intrigued by numbers.” —Kirkus Reviews “As much as any book I can name, Group Theory in the Bedroom conveys to a general audience the playfulness involved in doing mathematics: how questions arise as a form of play, how our first attempts at answering questions usually seem naive in hindsight but are crucial for finding eventual solutions, and how a good solution just feels right.” —David Austin, Notices of the AMS

Algebraic groups and Lie groups are important in most major areas of mathematics, occuring in diverse roles such as the symmetries of differential equations and as central figures in the Langlands program for number theory. In this book, Professor Borel looks at the development of the theory of Lie groups and algebraic groups, highlighting the evolution from the almost purely local theory at the start to the global theory that we know today. As the starting point of this passagefrom local to global, the author takes Lie's theory of local analytic transformation groups and Lie algebras. He then follows the globalization of the process in its two most important frameworks: (transcendental) differential geometry and algebraic geometry. Chapters II to IV are devoted to the former,Chapters V to VIII, to the latter.The essays in the first part of the book survey various proofs of the full reducibility of linear representations of $SL 2M$, the contributions H. Weyl to representation and invariant theory for Lie groups, and conclude with a chapter on E. Cartan's theory of symmetric spaces and Lie groups in the large.The second part of the book starts with Chapter V describing the development of the theory of linear algebraic groups in the 19th century. Many of the main contributions here are due to E. Study, E. Cartan, and above all, to L. Maurer. After being abandoned for nearly 50 years, the theory was revived by Chevalley and Kolchin and then further developed by many others. This is the focus of Chapter VI. The book concludes with two chapters on various aspects of the works of Chevalley on Lie groupsand algebraic groups and Kolchin on algebraic groups and the Galois theory of differential fields.The author brings a unique perspective to this study. As an important developer of some of the modern elements of both the differential geometric and the algebraic geometric sides of the theory, he has a particularly deep appreciation of the underlying mathematics. His lifelong involvement and his historical research in the subject give him a special appreciation of the story of its development.

The great Norwegian mathematician Sophus Lie developed the general theory of transformations in the 1870s, and the first part of the book properly focuses on his work. In the second part the central figure is Wilhelm Killing, who developed structure and classification of semisimple Lie algebras. The third part focuses on the developments of the representation of Lie algebras, in particular the work of Elie Cartan. The book concludes with the work of Hermann Weyl and his contemporaries on the structure and representation of Lie groups which serves to bring together much of the earlier work into a coherent theory while at the same time opening up significant avenues for further work.

Research and theory on intergroup contact have become one of the fastest advancing and most exciting fields in social psychology in recent years. The work is exciting because it combines basic social psychological concerns -- human interaction, situational influences on behavior -- with an effective means of improving intergroup relations at a time when the world is witnessing widespread intergroup hatred and strife. This volume provides an overview of this rapidly progressing area of investigation – its origins and early work, its current status and recent developments, along with criticisms of this work and suggestions for future directions. It covers a range of research findings involving contact between groups drawn from the authors’ extensive meta-analysis of 515 published studies on intergroup contact. This meta-analysis, together with the authors’ renowned research on intergroup contact, provides a solid foundation and broad overview of the field, to which have been added discussions of research extensions and emerging directions. When Groups Meet is a rich, comprehensive overview of classic and contemporary work on intergroup contact, and provides insights into where this work is headed in the future. For research specialists, this volume not only serves as a sourcebook for research and theory on intergroup contact, it also provides the entire 515-item bibliography from the meta-analysis. The clear structure and accessible writing style will also appeal to advanced undergraduate and graduate students in psychology and other social sciences.