"This book is both a concise introduction to the central results and methods of structural proof theory and a work of research that will be of interest to specialists. The book is designed to be used by students of philosophy, mathematics, and computer science." "The book contains a wealth of new results on proof-theoretical systems, including extensions of such systems from logic to mathematics, and on the connection between the two main forms of structural proof theory - natural deduction and sequent calculus. The authors emphasize the computational context of logical results." "A special feature of the volume is a computerized system for developing proofs interactively, downloadable from the web and regularly updated."--BOOK JACKET.