Duke Mathematical Journal

Without specializing in a small number of subject areas, this journal emphasizes the most active and influential areas of current mathematics.

This collection celebrates the pathbreaking work in game theory and mathematics of John F. Nash Jr., winner of the 1994 Nobel Prize in Economics. Nash's analysis of equilibria in the theory of non-cooperative games has had a major impact on modern economic theory. This book, also published as volume 81 of the Duke Mathematical Journal, includes an important, but previously unpublished paper by Nash; the proceedings of the Nobel seminar held in Stockholm on December 8, 1994 in his honor; and papers by distinguished mathematicians and economists written in response to and in honor of Nash's pioneering contributions to those fields. In 1950, when he was 22 years old, Nash presented his key idea--the Nash equilibrium--in the Ph.D. thesis he submitted to the Mathematics Department at Princeton University. In that paper, he defined a new concept of equilibrium and used methods from topology to prove the existence of an equilibrium point for n-person, finite, non-cooperative games, that is, for games in which the number of possible strategies are limited, no communication is allowed between the players, and n represents the number of players. The Nash equilibrium point is reached when none of the players can improve their position by changing strategies. By taking into account situations involving more than two players, specifically the general n-player game, Nash built significantly on the previous work of John Von Neumann and Oskar Morgenstern. Contributors. Abbas Bahri, Eric A. Carlen, Ennio De Giorgi, Charles Fefferman, Srihari Govidan, John C. Harsanyi, H. Hoffer, Carlos E. Kenig, S. Klainerman, Harold F. Kuhn, Michael Loss, William F. Lucas, M. Machedon, Roger B. Myerson, Raghavan Narasimhan, John F. Nash Jr., Louis Nirenberg, Jill Pipher, Zeév Rudnick, Peter Sarnak, Michael Shub, Steve Smale, Robert Wilson, K. Wysocki, E. Zehnder

In How Economics Became a Mathematical Science E. Roy Weintraub traces the history of economics through the prism of the history of mathematics in the twentieth century. As mathematics has evolved, so has the image of mathematics, explains Weintraub, such as ideas about the standards for accepting proof, the meaning of rigor, and the nature of the mathematical enterprise itself. He also shows how economics itself has been shaped by economists’ changing images of mathematics. Whereas others have viewed economics as autonomous, Weintraub presents a different picture, one in which changes in mathematics—both within the body of knowledge that constitutes mathematics and in how it is thought of as a discipline and as a type of knowledge—have been intertwined with the evolution of economic thought. Weintraub begins his account with Cambridge University, the intellectual birthplace of modern economics, and examines specifically Alfred Marshall and the Mathematical Tripos examinations—tests in mathematics that were required of all who wished to study economics at Cambridge. He proceeds to interrogate the idea of a rigorous mathematical economics through the connections between particular mathematical economists and mathematicians in each of the decades of the first half of the twentieth century, and thus describes how the mathematical issues of formalism and axiomatization have shaped economics. Finally, How Economics Became a Mathematical Science reconstructs the career of the economist Sidney Weintraub, whose relationship to mathematics is viewed through his relationships with his mathematician brother, Hal, and his mathematician-economist son, the book’s author.

Is there a vector space whose dimension is the golden ratio? Of course not—the golden ratio is not an integer! But this can happen for generalizations of vector spaces—objects of a tensor category. The theory of tensor categories is a relatively new field of mathematics that generalizes the theory of group representations. It has deep connections with many other fields, including representation theory, Hopf algebras, operator algebras, low-dimensional topology (in particular, knot theory), homotopy theory, quantum mechanics and field theory, quantum computation, theory of motives, etc. This book gives a systematic introduction to this theory and a review of its applications. While giving a detailed overview of general tensor categories, it focuses especially on the theory of finite tensor categories and fusion categories (in particular, braided and modular ones), and discusses the main results about them with proofs. In particular, it shows how the main properties of finite-dimensional Hopf algebras may be derived from the theory of tensor categories. Many important results are presented as a sequence of exercises, which makes the book valuable for students and suitable for graduate courses. Many applications, connections to other areas, additional results, and references are discussed at the end of each chapter.

Without specializing in a small number of subject areas, this journal emphasizes the most active and influential areas of current mathematics.

In the recently published book of E. Bodewig, Matrix Calculus some results of the earlier parts of this paper are mentioned. It is stated there that they are of theoretical interest, but have no practical value. In this paper it will be shown that they can easily be used for practical computations.

Over the last 50 years the theory of p-adic differential equations has grown into an active area of research in its own right, and has important applications to number theory and to computer science. This book, the first comprehensive and unified introduction to the subject, improves and simplifies existing results as well as including original material. Based on a course given by the author at MIT, this modern treatment is accessible to graduate students and researchers. Exercises are included at the end of each chapter to help the reader review the material, and the author also provides detailed references to the literature to aid further study.

How is that when scientists need some piece of mathematics through which to frame their theory, it is there to hand? Bueno and French offer a new approach to the puzzle of the applicability of mathematics, through a detailed examination of a series of case studies from the history of twentieth-century physics.