Helmut Schwichtenberg – författare

Driven by the question, 'What is the computational content of a (formal) proof?', this book studies fundamental interactions between proof theory and computability. It provides a unique self-contained text for advanced students and researchers in mathematical logic and computer science. Part I covers basic proof theory, computability and Gödel's theorems. Part II studies and classifies provable recursion in classical systems, from fragments of Peano arithmetic up to Π11-CA0. Ordinal analysis and the (Schwichtenberg-Wainer) subrecursive hierarchies play a central role and are used in proving the 'modified finite Ramsey' and 'extended Kruskal' independence results for PA and Π11-CA0. Part III develops the theoretical underpinnings of the first author's proof assistant MINLOG. Three chapters cover higher-type computability via information systems, a constructive theory TCF of computable functionals, realizability, Dialectica interpretation, computationally significant quantifiers and connectives and polytime complexity in a two-sorted, higher-type arithmetic with linear logic.

Constructive mathematics - mathematics in which 'there exists' always means 'we can construct' - is enjoying a renaissance. fifty years on from Bishop's groundbreaking account of constructive analysis, constructive mathematics has spread out to touch almost all areas of mathematics and to have profound influence in theoretical computer science. This handbook gives the most complete overview of modern constructive mathematics, with contributions from leading specialists surveying the subject's myriad aspects. Major themes include: constructive algebra and geometry, constructive analysis, constructive topology, constructive logic and foundations of mathematics, and computational aspects of constructive mathematics. A series of introductory chapters provides graduate students and other newcomers to the subject with foundations for the surveys that follow. Edited by four of the most eminent experts in the field, this is an indispensable reference for constructive mathematicians and a fascinating vista of modern constructivism for the increasing number of researchers interested in constructive approaches.

As society comes to rely increasingly on software for its welfare and prosperity there is an urgent need to create systems in which it can trust. Experience has shown that confidence can only come from a more profound understanding of the issues, which in turn can come only if it is based on logically sound foundations. This volume contains contributions from leading researchers in the critical disciplines of computing and information science, mathematics, logic, and complexity. All contributions are self-contained, aiming at comprehensibility as well as comprehensiveness. The volume also contains introductory hints to technical issues, concise surveys, introductions, and various fresh results and new perspectives.

As society comes to rely increasingly on software for its welfare and prosperity there is an urgent need to create systems in which it can trust. Experience has shown that confidence can only come from a more profound understanding of the issues, which in turn can come only if it is based on logically sound foundations. This volume contains contributions from leading researchers in the critical disciplines of computing and information science, mathematics, logic, and complexity. All contributions are self-contained, aiming at comprehensibility as well as comprehensiveness. The volume also contains introductory hints to technical issues, concise surveys, introductions, and various fresh results and new perspectives.

For some years, specification of software and hardwaresystems has been influenced not only by algebraic methodsbut also by new developments in logic. These newdevelopments in logic are partly based on the use ofalgorithmic techniques in deduction and proving methods, butare alsodue to new theoretical advances, to a great extentstimulated by computer science, which have led to new typesof logic and new logical calculi. The new techniques, methods and tools from logic, combined with algebra-basedones, offer very powerful and useful tools for the computerscientist, which may soon become practical for commercialuse, where, in particular, more powerful specification toolsare needed for concurrent and distributed systems. This volume contains papers based on lectures by leadingresearchers which were originally given at an internationalsummer school held in Marktoberdorf in 1991. The papers aimto give a foundation for combining logic and algebra for thepurposes of specification under the aspects of automateddeduction, proving techniques, concurrency and logic, abstract data types and operational semantics, andconstructive methods.

The latest work by the world's leading authorities on the use of formal methods in computer science is presented in this volume, based on the 1995 International Summer School in Marktoberdorf, Germany. Logic is of special importance in computer science, since it provides the basis for giving correct semantics of programs, for specification and verification of software, and for program synthesis. The lectures presented here provide the basic knowledge a researcher in this area should have and give excellent starting points for exploring the literature. Topics covered include semantics and category theory, machine based theorem proving, logic programming, bounded arithmetic, proof theory, algebraic specifications and rewriting, algebraic algorithms, and type theory.

Recent developments in computer science clearly show the need for a better theoretical foundation for some central issues. Methods and results from mathematical logic, in particular proof theory and model theory, are of great help here and will be used much more in future than previously. This book provides an excellent introduction to the interplay of mathematical logic and computer science. It contains extensively reworked versions of the lectures given at the 1997 Marktoberdorf Summer School by leading researchers in the field.Topics covered include: proof theory and specification of computation (J.-Y. Girard, D. Miller), complexity of proofs and programs (S. R. Buss, S. S. Wainer), computational content of proofs (H. Schwichtenberg), constructive type theory (P. Aczel, H. Barendregt, R. L. Constable), computational mathematics, (U. Martin), rewriting logic (J. Meseguer), and game semantics (S. Abramski).

CSL is the annual conference of the European Association for Computer Science Logic (EACSL). CSL2000 is the 14th such annual conference, thus witnessing the importance and sustained international interest in the application of me- ods from mathematical logic to computer science. The current conference was organized by the Mathematics Institute and the Computer Science Institute of the Ludwig-Maximilians-Universit. at Munc .. hen (LMU), with generous ?nancial supportfromtheDeutscheForschungsgemeinschaft,Forschungsinstitutfur .. an- wandte Softwaretechnologie (FAST e.V.), Munc .. hener Universit. atsgesellschaft e.V., and Siemens AG. Our sponsors' generosity enabled, among other things, stipends for the ?nancial support of students as well as of researchers from Ea- ern Europe. Topics in the call for papers for CSL2000 included: automated deduction andinteractivetheoremproving,categoricallogicandtopologicalsemantics,c- structivemathematicsandtypetheory,domaintheory,equationallogicandterm rewriting, ?nite model theory, database theory, higher order logic, lambda and combinatory calculi, logical aspects of computational complexity, logical fo- dations of programming paradigms, logic programming and constraints, linear logic, modal and temporal logics, model checking, program extraction, program logicsandsemantics,programspeci?cation,transformationandveri?cation.The invited speakers were: Moshe Vardi (Houston), Paul Beame (Washington), - dreas Blass (Ann Arbor), Egon B.. orger (Pisa), Yuri Gurevich (Redmond), Bruno Poizat (Lyons), Wolfram Schulte (Redmond), Saharon Shelah (Jerusalem), and Colin Sterling (Edinburgh). Special thanks to Moshe Vardi for being willing to speakintheplaceofMikl' osAjtai(Almaden),whocouldnotattendthemeeting. The day of 24 August 2000, during the week-long CSL2000 meeting, was reserved for theGurevichSymposium, a special, one-day tribute to the scienti?c contributions of Professor Yuri Gurevich, at the occasion of his 60th birthday.

For some years, specification of software and hardwaresystems has been influenced not only by algebraic methodsbut also by new developments in logic. These newdevelopments in logic are partly based on the use ofalgorithmic techniques in deduction and proving methods, butare alsodue to new theoretical advances, to a great extentstimulated by computer science, which have led to new typesof logic and new logical calculi. The new techniques,methods and tools from logic, combined with algebra-basedones, offer very powerful and useful tools for the computerscientist, which may soon become practical for commercialuse, where, in particular, more powerful specification toolsare needed for concurrent and distributed systems.This volume contains papers based on lectures by leadingresearchers which were originally given at an internationalsummer school held in Marktoberdorf in 1991. The papers aimto give a foundation for combining logic and algebra for thepurposes of specification under the aspects of automateddeduction, proving techniques, concurrency and logic,abstract data types and operational semantics, andconstructive methods.

Recent developments in computer science clearly show the need for a better theoretical foundation for some central issues. Methods and results from mathematical logic, in particular proof theory and model theory, are of great help here and will be used much more in future than previously. This book provides an excellent introduction to the interplay of mathematical logic and computer science. It contains extensively reworked versions of the lectures given at the 1997 Marktoberdorf Summer School by leading researchers in the field.Topics covered include: proof theory and specification of computation (J.-Y. Girard, D. Miller), complexity of proofs and programs (S. R. Buss, S. S. Wainer), computational content of proofs (H. Schwichtenberg), constructive type theory (P. Aczel, H. Barendregt, R. L. Constable), computational mathematics, (U. Martin), rewriting logic (J. Meseguer), and game semantics (S. Abramski).

The Marktoberdorf Summer School 1995 'Logic of Computation' was the 16th in a series of Advanced Study Institutes under the sponsorship of the NATO Scientific Affairs Division held in Marktoberdorf. Its scientific goal was to survey recent progress on the impact of logical methods in software development. The courses dealt with many different aspects of this interplay, where major progress has been made. Of particular importance were the following. • The proofs-as-programs paradigm, which makes it possible to extract verified programs directly from proofs. Here a higher order logic or type theoretic setup of the underlying language has developed into a standard. • Extensions of logic programming, e.g. by allowing more general formulas and/or higher order languages. • Proof theoretic methods, which provide tools to deal with questions of feasibility of computations and also to develop a general mathematical understanding of complexity questions. • Rewrite systems and unification, again in a higher order context. Closely related is the now well-established Grabner basis theory, which recently has found interesting applications. • Category theoretic and more generally algebraic methods and techniques to analyze the semantics of programming languages. All these issues were covered by a team of leading researchers. Their courses were grouped under the following headings.

Logical concepts and methods are of growing importance in many areas of computer science. The proofs-as-programs paradigm and the wide acceptance of Prolog show this clearly. The logical notion of a formal proof in various constructive systems can be viewed as a very explicit way to describe a computation procedure. Also conversely, the development of logical systems has been influenced by accumulating knowledge on rewriting and unification techniques. This volume contains a series of lectures by leading researchers giving a presentation of new ideas on the impact of the concept of a formal proof on computation theory. The subjects covered are: specification and abstract data types, proving techniques, constructive methods, linear logic, and concurrency and logic.

This book is for graduate students and researchers, introducing modern foundational research in mathematics, computer science, and philosophy from an interdisciplinary point of view. Its scope includes proof theory, constructive mathematics and type theory, univalent mathematics and point-free approaches to topology, extraction of certified programs from proofs, automated proofs in the automotive industry, as well as the philosophical and historical background of proof theory. By filling the gap between (under-)graduate level textbooks and advanced research papers, the book gives a scholarly account of recent developments and emerging branches of the aforementioned fields.