Advances In Representation Theory Complex Analysis And Integral Geometry

This volume targets graduate students and researchers in the fields of representation theory, automorphic forms, Hecke algebras, harmonic analysis, number theory.

This volume consists of contributions invited articles from the MPI-summer program on representation theory in 2007. There will be an even mix of high quality overview articles and original research contributions. The targeted audience is graduate students and researchers in representation theory, harmonic analysis, automorphic forms, number theory, and locally symmetric spaces.

This volume, the second of Helgason's impressive three books on Lie groups and the geometry and analysis of symmetric spaces, is an introduction to group-theoretic methods in analysis on spaces with a group action. The first chapter deals with the three two-dimensional spaces of constant curvature, requiring only elementary methods and no Lie theory. It is remarkably accessible and would be suitable for a first-year graduate course. The remainder of the book covers more advanced topics, including the work of Harish-Chandra and others, but especially that of Helgason himself. Indeed, the exposition can be seen as an account of the author's tremendous contributions to the subject.Chapter I deals with modern integral geometry and Radon transforms. The second chapter examines the interconnection between Lie groups and differential operators. Chapter IV develops the theory of spherical functions on semisimple Lie groups with a certain degree of completeness, including a study of Harish-Chandra's $c$-function. The treatment of analysis on compact symmetric spaces (Chapter V) includes some finite-dimensional representation theory for compact Lie groups and Fourier analysis on compact groups. Each chapter ends with exercises (with solutions given at the end of the book!) and historical notes.This book, which is new to the AMS publishing program, is an excellent example of the author's well-known clear and careful writing style. It has become the standard text for the study of spherical functions and invariant differential operators on symmetric spaces. Sigurdur Helgason was awarded the Steele Prize for Groups and Geometric Analysis and the companion volume, ""Differential Geometry, Lie Groups and Symmetric Spaces.""

"The book is largely self-contained...There is a nice introduction to symplectic geometry and a charming exposition of equivariant K-theory. Both are enlivened by examples related to groups...An attractive feature is the attempt to convey some informal ‘wisdom’ rather than only the precise definitions. As a number of results [are] due to the authors, one finds some of the original excitement. This is the only available introduction to geometric representation theory...it has already proved successful in introducing a new generation to the subject." (Bulletin of the AMS)

This book is an elementary self-contained introduction to some constructions of representation theory and related topics of differential geometry and analysis. Topics covered include the theory of various Fourier-like integral operators such as Segal-Bargmann transforms, Gaussian integral operators in $L^2$ and in the Fock space, integral operators with theta-kernels, the geometry of real and $p$-adic classical groups and symmetric spaces. The heart of the book is the Weil representation of the symplectic group (real and complex realizations, relations with theta-functions and modular forms, $p$-adic and adelic constructions) and representations in Hilbert spaces of holomorphic functions of several complex variables. This book is addressed to graduate students and researchers in representation theory, differential geometry, and operator theory. Prerequisites are standard university courses in linear algebra, functional analysis, and complex analysis.

[see attached] This second edition of {\it Representation Theory and Complex Geometry} provides an overview of significant advances in representation theory from a geometric standpoint. A geometrically-oriented treatment has long been desired, especially since the discovery of {\cal D}-modules in the early '80s and the quiver approach to quantum groups in the early '90s. The first half of the book fills the gap between the standard knowledge of a beginner in Lie theory and the much wider background needed by the working mathematician. Thus, Chapters 1-3 and 5-6 provide some basics in symplectic geometry, Borel--Moore homology, the geometry of semisimple groups, equivariant algebraic K-theory "from scratch," and the topology and algebraic geometry of flag varieties and conjugacy classes, respectively. The material covered by Chapters 5 and 6, as well as most of Chapter 3, has never been presented in book form. Chapters 3-4 and 7-8 present a uniform approach to representation theory of three quite different objects: Weyl groups, Lie algebra sln, and the Iwahori--Hecke algebra. The results of Chapters 4 and 8, with complete proofs are not to be found elsewhere in the literature. This second edition contains substantial updates and revisions to include more standard classical results in chapters 2, 3, 5, and 6 as well as two new chapters. Chapter 9 treats the applications of {\cal D}-modules to Lie groups, and includes the study of * Differential operators on a semisimple group and on its flag manifold; * the famous Beilinson--Bernstein Localization Theorem reducing the study of {\it g}-modules to that of {\cal D} modules; * the so-called Harish--Chandra holonomic system. Chapter 10 isdevoted to some very exciting developments connecting the representations of quantum groups to the geometry of "quiver varieties," introduced by Lusztig and Nakajima. The subject is closely related to many other important topics such as the McKay correspondence, semismall resolutions and Hilbert schemes. Overall, this chapter puts the representation theory of Kac--Moody algebras and quantum groups in this broader context. The exposition is practically self-contained with each chapter potentially serving as a basis for a graduate course or seminar. An excellent glossary of notation, comprehensive bibliography and extensive index round out this new edition. The techniques developed here play an essential role in the development of the Langlands program and can be successfully applied to representation theory, quantum groups and quantum field theory, affine Lie algebras, algebraic geometry, and mathematical physics.

Comprising a selection of expository and research papers, Harmonic Analysis and Integral Geometry grew from presentations offered at the July 1998 Summer University of Safi, Morocco-an annual, advanced research school and congress. This lively and very successful event drew the attendance of many top researchers, who offered both individual lectures and coordinated courses on specific research topics within this fast growing subject. Harmonic Analysis and Integral Geometry presents important recent advances in the fields of Radon transforms, integral geometry, and harmonic analysis on Lie groups and symmetric spaces. Several articles are devoted to the new theory of Radon transforms on trees. With its related presentations addressing recent developments in various aspects of these intriguing areas of study, Harmonic Analysis and Integral Geometry becomes an important addition not only to the Research Notes in Mathematics series, but to the general mathematics literature.