All traditional implementation techniques for functional languages fail to avoid useless repetition of work. They are not "optimal" in their implementation of sharing, often causing a catastrophic, exponential explosion in reduction time. Optimal reduction is an innovative graph reduction technique for functional expressions, introduced by Lamping in 1990, that solves the sharing problem. This work, the first on the subject, is a comprehensive account by two of its leading exponents. Practical implementation aspects are fully covered as are the mathematical underpinnings of the subject. The relationship to the pioneering work of Lévy and to Girard's more recent "Geometry of Interaction" are explored; optimal reduction is thereby revealed as a prime example of how a beautiful mathematical theory can lead to practical benefit. The book is essentially self-contained, requiring no more than basic familiarity with functional languages. It will be welcomed by graduate students and research workers in lambda calculus, functional programming or linear logic.

TheInternationalConferenceonMathematicalKnowledgeManagementhasnow reached its third edition, creating and establishing an original and stimulating scienti?ccommunitytransversaltomanydi?erent?eldsandresearchtopics. The broad goal of MKM is the exploration of innovative, semantically enriched, d- ital encodings of mathematical information, and the study of new services and tools exploiting the machine-understandable nature of the information. MKM is naturally located in the border area between digital libraries and the mec- nization of mathematics, devoting a particular interest to the new developments in information technology, and fostering their application to the realm of ma- ematical information. The conference is meant to be a forum for presenting, discussing and comparing new tools and systems, standardization e?orts, cri- calsurveys, largeexperiments, andcasestudies. Atpresent, wearestillgettingto knoweachother, tounderstandtheworkdonebyotherpeople, andthepotenti- ities o?ered by their work to our own research activity. However, the conference is rapidly acquiring scienti?c strength and academic interest, attracting more and more people and research groups, and o?ering a challenging alternative to older, more conservative conferences. July 2004 Andrea Asperti Grzegorz Bancerek Andrzej Trybulec Organization MKM 2004 was organized by the Institute of Computer Science, University of Bia lystokinco-operationwiththeFacultyofComputerScience, Bia lystokTe- nical University and the Association of Mizar Users. Program Committee Andrzej Trybulec (Chair) University of Bia lystok, Poland Andrew A. Adams University of Reading, UK Andrea Asperti University of Bologna, Italy Bruno Buchberger RISC Linz, Austria Roy McCasland University of Edinburgh, UK James Davenport University of Bath, UK Will

This book constitutes the refereed proceedings of the Second International Conference on Mathematical Knowledge Management, MKM 2003, held in Betinoro, Italy, in February 2003. The 16 revised full papers presented together with an invited paper were carefully reviewed and selected for presentation. Among the topics addressed are digitization, representation, formalization, proof assistants, distributed libraries of mathematics, NAG library, LaTeX, MathML, mathematics markup, theorem description, query languages for mathematical metadata, mathematical information retrieval, XML-based mathematical knowledge processing, semantic Web, mathematical content management, formalized mathematics repositories, theorem proving, and proof theory.