A central concern of number theory is the study of local-to-global principles, which describe the behavior of a global field K in terms of the behavior of various completions of K. This book looks at a specific example of a local-to-global principle: Weil's conjecture on the Tamagawa number of a semisimple algebraic group G over K. In the case where K is the function field of an algebraic curve X, this conjecture counts the number of G-bundles on X (global information) in terms of the reduction of G at the points of X (local information). The goal of this book is to give a conceptual proof of Weil's conjecture, based on the geometry of the moduli stack of G-bundles. Inspired by ideas from algebraic topology, it introduces a theory of factorization homology in the setting -adic sheaves. Using this theory, Dennis Gaitsgory and Jacob Lurie articulate a different local-to-global principle: a product formula that expresses the cohomology of the moduli stack of G-bundles (a global object) as a tensor product of local factors. Using a version of the Grothendieck-Lefschetz trace formula, Gaitsgory and Lurie show that this product formula implies Weil's conjecture. The proof of the product formula will appear in a sequel volume.

Many of the developments of modern algebraic geometry and topology stem from the ideas of S. Lefschetz. These are featured in this volume of contemporary research papers contributed by mathematical colleagues to celebrate his seventieth birthday. Originally published in 1957. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.

In dem Lehrbuch wird eine mathematisch orientierte Einfuhrung in die algorithmische Geometrie gegeben. Im ersten Teil werden "klassische" Probleme und Techniken behandelt, die sich auf polyedrische (= linear begrenzte) Objekte beziehen. Hierzu gehoeren beispielsweise Algorithmen zur Berechnung konvexer Hullen und die Konstruktion von Voronoi-Diagrammen. Im zweiten Teil werden grundlegende Methoden der algorithmischen algebraischen Geometrie entwickelt und anhand von Anwendungen aus Computergrafik, Kurvenrekonstruktion und Robotik illustriert. Das Buch eignet sich fur ein fortgeschrittenes Modul in den derzeit neu konzipierten Bachelor-Studiengangen in Mathematik und Informatik.

Algebraic geometry, central to pure mathematics, has important applications in such fields as engineering, computer science, statistics and computational biology, which exploit the computational algorithms that the theory provides. Users get the full benefit, however, when they know something of the underlying theory, as well as basic procedures and facts. This book is a systematic introduction to the central concepts of algebraic geometry most useful for computation. Written for advanced undergraduate and graduate students in mathematics and researchers in application areas, it focuses on specific examples and restricts development of formalism to what is needed to address these examples. In particular, it introduces the notion of Grobner bases early on and develops algorithms for almost everything covered. It is based on courses given over the past five years in a large interdisciplinary programme in computational algebraic geometry at Rice University, spanning mathematics, computer science, biomathematics and bioinformatics.

Cet ouvrage est consacre a l'arithmetique des surfaces fibrees en courbes de genre 1 au-dessus de la droite projective, et a l'arithmetique des intersections de deux quadriques dans l'espace projectif. Swinnerton-Dyer introduisit en 1993 une technique permettant d'etudier les points rationnels des pinceaux de courbes de genre 1. La premiere moitie de l'ouvrage reprend et developpe cette technique ainsi que ses generalisations ulterieures. La seconde moitie, qui repose sur la premiere, porte sur les surfaces de del Pezzo de degre 4 et sur les intersections de deux quadriques de dimension superieure; les resultats annonces dans C. R. Math. Acad. Sci. Paris 342 (2006), no. 4, 223--227] y sont demontres."

This text-based on the author's popular courses at Pomona College-provides a readable, student-friendly, and somewhat sophisticated introduction to abstract algebra. It is aimed at sophomore or junior undergraduates who are seeing the material for the first time. In addition to the usual definitions and theorems, there is ample discussion to help students build intuition and learn how to think about the abstract concepts. The book has over 1300 exercises and mini-projects of varying degrees of difficulty, and, to facilitate active learning and self-study, hints and short answers for many of the problems are provided. There are full solutions to over 100 problems in order to augment the text and to model the writing of solutions. Lattice diagrams are used throughout to visually demonstrate results and proof techniques. The book covers groups, rings, and fields. In group theory, group actions are the unifying theme and are introduced early. Ring theory is motivated by what is needed for solving Diophantine equations, and, in field theory, Galois theory and the solvability of polynomials take center stage. In each area, the text goes deep enough to demonstrate the power of abstract thinking and to convince the reader that the subject is full of unexpected results.

Le but de cet ouvrage est de faire une prA(c)sentation complA]te et auto contenue de l'A(c)quivalence entre les Oracles "SA(c)parer, " "Optimiser "et "Appartenir "en Optimisation PolyA(c)drale. Dans ce but le livre commence par une prA(c)sentation dA(c)taillA(c)e des problA]mes de ComplexitA(c) des Algorithmes suivi d'une prA(c)sentation de la mA(c)thode du Simplexe. On dA(c)crit ensuite l'algorithme de Khachiyan sans A(c)luder les problA]mes numA(c)riques. Viennent alors une suite d'algorithmes polynomiaux pour "Optimiser" A partir de l'oracle "SA(c)parer." AprA]s quelques transformations, on montre que, par polaritA(c), on peut "SA(c)parer" A partir de l'oracle "Optimiser." La premiA]re A(c)quivalence est revue aprA]s avoir dA(c)crit l'algorithme "LLL." L'ouvrage se termine par la rA(c)duction de "SA(c)parer" A "Appartenir. "

This volume contains a collection of research papers dedicated to Hans Grauert on the occasion of his seventieth birthday. Hans Grauert is a pioneer in modern complex analysis, continuing the il lustrious German tradition in function theory of several complex variables of Weierstrass, Behnke, Thullen, Stein, Siegel, and many others. When Grauert came on the scene in the early 1950's, function theory was going through a revolutionary period with the geometric theory of complex spaces still in its embryonic stage. A rich theory evolved with the joint efforts of many great mathematicians including Oka, Kodaira, Cartan, and Serre. The Car tan Seminar in Paris and the Kodaira Seminar provided important venues an for its development. Grauert, together with Andreotti and Remmert, took active part in the latter. In his career he has nurtured a great number of his own doctoral students as well as other young mathematicians in his field from allover the world. For a couple of decades his work blazed the trail and set the research agenda in several complex variables worldwide. Among his many fundamentally important contributions, which are too numerous to completely enumerate here, are: 1. The complete clarification of various notions of complex spaces. 2. The solution of the general Levi problem and his work on pseudo convexity for general manifolds. 3. The theory of exceptional analytic sets. 4. The Oka principle for holomorphic bundles. 5. The proof of the Mordell conjecture for function fields. 6. The direct image theorem for coherent sheaves."

Lectures: A. Beauville: Surfaces algebriques complexes.- F.A. Bogomolov: The theory of invariants and its applications to some problems in the algebraic geometry.- E. Bombieri: Methods of algebraic geometry in Char. P and their applications.- Seminars: F. Catanese: Pluricanonical mappings of surfaces with K(2) =1,2, q=pg=0.- F. Catanese: On a class of surfaces of general type.- I. Dolgacev: Algebraic surfaces with p=pg =0.- A. Tognoli: Some remarks about the "Nullstellensatz".

The subject of elliptic curves is one of the jewels of nineteenth-century mathematics, whose masters were Abel, Gauss, Jacobi, and Legendre. This book presents an introductory account of the subject in the style of the original discoverers, with references to and comments about more recent and modern developments. It combines three of the fundamental themes of mathematics: complex function theory, geometry, and arithmetic. After an informal preparatory chapter, the book follows a historical path, beginning with the work of Abel and Gauss on elliptic integrals and elliptic functions. This is followed by chapters on theta functions, modular groups and modular functions, the quintic, the imaginary quadratic field, and on elliptic curves. The many exercises with hints scattered throughout the text give the reader a glimpse of further developments. Requiring only a first acquaintance with complex function theory, this book is an ideal introduction to the subject for graduate students and researchers in mathematics and physics.

The aim of this book is to study various geometric properties and algebraic invariants of smooth projective varieties with infinite fundamental groups. This approach allows for much interplay between methods of algebraic geometry, complex analysis, the theory of harmonic maps, and topology. Making systematic use of Shafarevich maps, a concept previously introduced by the author, this work isolates those varieties where the fundamental group influences global properties of the canonical class.

The book is primarily geared toward researchers and graduate students in algebraic geometry who are interested in the structure and classification theory of algebraic varieties. There are, however, presentations of many other applications involving other topics as well--such as Abelian varieties, theta functions, and automorphic forms on bounded domains. The methods are drawn from diverse sources, including Atiyah's "L2 "-index theorem, Gromov's theory of Poincare series, and recent generalizations of Kodaira's vanishing theorem.

Originally published in 1995.

The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These paperback editions preserve the original texts of these important books while presenting them in durable paperback editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905."

From the reviews: "Although several textbooks on modern algebraic geometry have been published in the meantime, Mumford's "Volume I" is, together with its predecessor the red book of varieties and schemes, now as before one of the most excellent and profound primers of modern algebraic geometry. Both books are just true classics " Zentralblatt

Mumford-Tate groups are the fundamental symmetry groups of Hodge theory, a subject which rests at the center of contemporary complex algebraic geometry. This book is the first comprehensive exploration of Mumford-Tate groups and domains. Containing basic theory and a wealth of new views and results, it will become an essential resource for graduate students and researchers.

Although Mumford-Tate groups can be defined for general structures, their theory and use to date has mainly been in the classical case of abelian varieties. While the book does examine this area, it focuses on the nonclassical case. The general theory turns out to be very rich, such as in the unexpected connections of finite dimensional and infinite dimensional representation theory of real, semisimple Lie groups. The authors give the complete classification of Hodge representations, a topic that should become a standard in the finite-dimensional representation theory of noncompact, real, semisimple Lie groups. They also indicate that in the future, a connection seems ready to be made between Lie groups that admit discrete series representations and the study of automorphic cohomology on quotients of Mumford-Tate domains by arithmetic groups. Bringing together complex geometry, representation theory, and arithmetic, this book opens up a fresh perspective on an important subject.

This monograph establishes a general context for the cohomological use of Hironaka's theorem on the resolution of singularities. It presents the theory of cubical hyperresolutions, and this yields the cohomological properties of general algebraic varieties, following Grothendieck's general ideas on descent as formulated by Deligne in his method for simplicial cohomological descent. These hyperresolutions are applied in problems concerning possibly singular varieties: the monodromy of a holomorphic function defined on a complex analytic space, the De Rham cohmomology of varieties over a field of zero characteristic, Hodge-Deligne theory and the generalization of Kodaira-Akizuki-Nakano's vanishing theorem to singular algebraic varieties. As a variation of the same ideas, an application of cubical quasi-projective hyperresolutions to algebraic K-theory is given.

The study of the mapping class group Mod("S") is a classical topic that is experiencing a renaissance. It lies at the juncture of geometry, topology, and group theory. This book explains as many important theorems, examples, and techniques as possible, quickly and directly, while at the same time giving full details and keeping the text nearly self-contained. The book is suitable for graduate students.

"A Primer on Mapping Class Groups" begins by explaining the main group-theoretical properties of Mod("S"), from finite generation by Dehn twists and low-dimensional homology to the Dehn-Nielsen-Baer theorem. Along the way, central objects and tools are introduced, such as the Birman exact sequence, the complex of curves, the braid group, the symplectic representation, and the Torelli group. The book then introduces Teichmuller space and its geometry, and uses the action of Mod("S") on it to prove the Nielsen-Thurston classification of surface homeomorphisms. Topics include the topology of the moduli space of Riemann surfaces, the connection with surface bundles, pseudo-Anosov theory, and Thurston's approach to the classification."

Es wird geschiitzt, daf.\ man tiber kommutative Algebra und algebraische Geometrie beim derzeitigen Stand des Wissens eine 200 Semester dauernde Vorlesung halten konnte, in der man sich niemals wiederholen miiEte. Jede Einflihrung in eines dieser Gebiete muB daher eine strenge Stoffauswahl treffen. Ich will zunachst angeben, welche Gesichtspunkte im vorliegenden Buch nit die Wahl des behandelten Materials maBgebend waren. Diese Einflihrung ist aus Vorlesungen fur Studenten hervorgegangen, die schon einen Grundkurs in Algebra absolviert hatten, bei denen daher Kenntnisse in linearer Algebra, Ring-, Korper- und Galoistheorie vorausge- setzt werden konnten. Mit sehr viel mehr soUte auch nicht begonnen werden. Ich habe mir in der Vorlesung und imjetzigen Text vorgenommen, mit moglichst geringen Hilfsmitteln zu einigen neueren Resultaten der kommutativen Algebra und alge- braischen Geometrie hinzuftihren, die sich mit der Darstellung algebraischer Varietiiten als Durchschnitt von moglichst wenig Hyperf/iichen befassen und - damit eng gekoppel- mit der moglichst sparsamen Erzeugung von Idealen in noetherschen Ringen.

One of the most exciting new subjects in Algebraic Number Theory and Arithmetic Algebraic Geometry is the theory of Euler systems. Euler systems are special collections of cohomology classes attached to p-adic Galois representations. Introduced by Victor Kolyvagin in the late 1980s in order to bound Selmer groups attached to p-adic representations, Euler systems have since been used to solve several key problems. These include certain cases of the Birch and Swinnerton-Dyer Conjecture and the Main Conjecture of Iwasawa Theory. Because Selmer groups play a central role in Arithmetic Algebraic Geometry, Euler systems should be a powerful tool in the future development of the field.

Here, in the first book to appear on the subject, Karl Rubin presents a self-contained development of the theory of Euler systems. Rubin first reviews and develops the necessary facts from Galois cohomology. He then introduces Euler systems, states the main theorems, and develops examples and applications. The remainder of the book is devoted to the proofs of the main theorems as well as some further speculations.

The book assumes a solid background in algebraic Number Theory, and is suitable as an advanced graduate text. As a research monograph it will also prove useful to number theorists and researchers in Arithmetic Algebraic Geometry.

1m April 1961 hat die Firma Mannesmann AG einen Bericht tiber Versuche mit Stromungen urn Bundel von parallelen Rohren vorgelegt {I}. Diese Rohrbundel spielen beim Bau von Warmetauschern eine wichtige Rolle. EKperimentell wurde festgestellt, daB Rohre, die senkrecht zur Rohrachse angestromt werden und von elliptischem Querschnitt sind, in stromungs- und warmetechnischer Hin- sicht Kreisrohren uberlegen sind. Es zeigt sich, daB die Stromung fast der gesamten Rohrwand anliegt und die auftretenden Wirbelgebiete sehr klein sind (Abb. 1,1). Abb. 1,1 Es erschien deshalb interessant, diese Messungen durch mathematische Berechnungen zu erganzen. Man kann erwarten, daB der experimentelle Befund durch eine reibungsfreie ebene Potentialstromung gut wiedergegeben wird. Der Konstruktion solcher Stromungen ist die vorliegende Arbeit gewidmet. 1m erst en Teil der Arbeit wird die Berechnung der komplex en Potential- funktion einer Stromung urn mehrere Ellipsen auf die Losung eines modifizier- ten Dirichletproblems zuruckgefuhrt und numerisch ausgewertet. Da die numerische Auswertung dieses Losungsverfahrens relativ aufwendig ist, wird im zweiten Teil der Arbeit eine Naherungsmethode angegeben, die zur Berechnung des komplexen Potentials der Stromung nur die Losung 1inearer Gleichungssysteme erfordert. Bei den numerischen Berechnungen wurden nur solche Ell psen betrachtet, deren groBe Halbachen entsprechend Abb. 1,1 parallel r Anstromung ichtung liegen. 1m dritten Teil der Arbeit wird die Lage von Staupunkten im Stromungsgebiet an Hand von Beispielen untersucht, wahrend sich.der vierte Teil mit den Drucken im Stromungsgebiet beschaftigt.

In einer fruheren Arbeit {6} wurde eine Methode angegeben, die komplexe Potentialfunktion einer ebenen Potentialstromung im AuBengebiet von N Kreis- linien naherungsweise zu berechnen. Mittels dieses Losungsverfahrens wird im ersten Teil dieser Arbeit eine Potentialstromung urn N KreiszYlinder in einem Kanal mit festen Wanden berechnet. 1m zweiten Teil der Arbeit wird die elastische Verformung von Hindernissen, die einer inkompressiblen Stromung ausgesetzt sind, numerisch ausgewertet. Dabei ist vorausgesetzt, daB die Hindernisse nach der Verformung die Gestalt von Kreisscheiben besitzen. Die theoretischen Betrachtungen zur ebenen Elastizitatstheorie stutzen sich weitgehend auf die Ausfuhrungen von N.I. Muschelischwili {7}. Aile numerischen Rechnungen wurden an der Rechenanlage IBM 370/168 der Gesellschaft fur Mathematik und Datenverarbeitung in Bonn durchgefuhrt. An dieser Stelle mochte ich Herrn Prof. Dr. H. Wendt und Herrn Dr. R. Weizel fur die Anregung zu dieser Arbeit und die vielen Diskussionen danken. 2 1) Berechnung einer ebenen Potentialstromung um einen Kreiszylinder in einem Kanal mit festen Wanden t Gesucht ist die komplexe Potentialfunktion einer ebenen, stationaren, symmetrischen Potentialstromung in einem Kanal der Hohe 2p. p>l (Abb. 1)., ip. i...!... 2R ) Zp x i p Abbildung 1 Die Gleichung der Kanalwande Kl und K2 laute y =+/- P d.h. die x-Achse ist Symmetrieachse des Kanals. Der Koordinatenursprung sei der Mittelpunkt eines im Ka al liegenden Kreises K3 vom Radius Eins. Die An- stromgeschwindigkeit V (V=IVI) verlaufe parallel zur positiven reellen Achse.