One of the major concerns of theoretical computer science is the classifi cation of problems in terms of how hard they are. The natural measure of difficulty of a function is the amount of time needed to compute it (as a function of the length of the input). Other resources, such as space, have also been considered. In recursion theory, by contrast, a function is considered to be easy to compute if there exists some algorithm that computes it. We wish to classify functions that are hard, i.e., not computable, in a quantitative way. We cannot use time or space, since the functions are not even computable. We cannot use Turing degree, since this notion is not quantitative. Hence we need a new notion of complexity-much like time or spac~that is quantitative and yet in some way captures the level of difficulty (such as the Turing degree) of a function.

This book constitutes the refereed proceedings of the 21st International Symposium on Mathematical Foundations of Computer Science, MFCS '96, held in Crakow, Poland in September 1996. The volume presents 35 revised full papers selected from a total of 95 submissions together with 8 invited papers and 2 abstracts of invited talks. The papers included cover issues from the whole area of theoretical computer science, with a certain emphasis on mathematical and logical foundations. The 10 invited presentations are of particular value.

Second of two volumes providing a comprehensive guide to the current state of mathematical logic.

This volume contains the papers presented at the 29th Symposium on Mat- matical Foundations of Computer Science, MFCS 2004, held in Prague, Czech Republic, August 22–27, 2004. The conference was organized by the Institute for Theoretical Computer Science (ITI) and the Department of Theoretical Com- terScienceandMathematicalLogic(KTIML)oftheFacultyofMathematicsand Physics of Charles University in Prague. It was supported in part by the Eu- pean Association for Theoretical Computer Science (EATCS) and the European Research Consortium for Informatics and Mathematics (ERCIM). Traditionally, the MFCS symposia encourage high-quality research in all branches of theoretical computer science. Ranging in scope from automata, f- mal languages, data structures, algorithms and computational geometry to c- plexitytheory,modelsofcomputation,andapplicationsincludingcomputational biology, cryptography, security and arti?cial intelligence, the conference o?ers a unique opportunity to researchers from diverse areas to meet and present their results to a general audience. The scienti?c program of this year’s MFCS took place in the lecture halls of the recently reconstructed building of the Faculty of Mathematics and P- sics in the historical center of Prague, with the famous Prague Castle and other celebratedhistoricalmonumentsinsight.Theviewfromthewindowswasach- lengingcompetitionforthespeakersinthe?ghtfortheattentionoftheaudience. But we did not fear the result: Due to the unusually tough competition for this year’s MFCS, the admitted presentations certainly attracted considerable in- rest. The conference program (and the proceedings) consisted of 60 contributed papers selected by the Program Committee from a total of 167 submissions.

This book constitutes the refereed proceedings of the 24th International Conference on the Foundations of Software Technology and Theoretical Computer Science, FSTTCS 2004, held in Chennai, India, in December 2004. The 35 revised full papers presented together with 5 invited papers were carefully reviewed and selected from 176 submissions. The papers address a broad variety of current issues in software science, programming theory, systems design and analysis, formal methods, mathematical logic, mathematical foundations, discrete mathematics, combinatorial mathematics, complexity theory, automata theory, and theoretical computer science in general.

This volume contains the proceedings of the tenth annual Symposium on Theoretical Aspects of Computer Science (STACS '93), held in W}rzburg, February 25-27, 1993. The STACS symposia are held alternately in Germany and France, and organized jointly by the Special Interest Group for Theoretical Computer Science of the Gesellschaft f}r Informatik (GI) and theSpecial Interest Group for Applied Mathematics of the Association Francaise des Sciences et Technologies de l'Information et des Syst mes (afcet). The volume includes the three invited talks which opened the three days of the symposium: "Causal and distributed semantics for concurrent processes" (I. Castellani), "Parallel architectures: design and efficient use" (B. Monien et al.), and "Transparent proofs" (L. Babai). The selection of contributed papers is organized into parts on: computational complexity, logic in computer science, efficient algorithms, parallel and distributed computation, language theory, computational geometry, automata theory, semantics and logic of programming languages, automata theory and logic, circuit complexity, omega-automata, non-classical complexity, learning theory and cryptography, and systems.

"Integrates two classical approaches to computability. Offers detailed coverage of recent research at the interface of logic, computability theory, nd theoretical computer science. Presents new, never-before-published results and provides informtion not easily accessible in the literature."

This book constitutes the refereed proceedings of the 19th Annual Conference on Learning Theory, COLT 2006, held in Pittsburgh, Pennsylvania, USA in June 2006. The 43 revised full papers presented together with 2 articles on open problems and 3 invited lectures were carefully reviewed and selected from a total of 102 submissions. The papers cover a wide range of topics including clustering, un- and semisupervised learning, statistical learning theory, regularized learning and kernel methods, query learning and teaching, inductive inference, learning algorithms and limitations on learning, online aggregation, online prediction and reinforcement learning.

This book presents the proceedings of the 20th International Symposium on Mathematical Foundations of Computer Science, MFCS'95, held in Prague, Czech Republic in August/September 1995. The book contains eight invited papers and two abstracts of invited talks by outstanding scientists as well as 44 revised full research papers selected from a total of 104 submissions. All relevant aspects of theoretical computer science are addressed, particularly the mathematical foundations; the papers are organized in sections on structural complexity, algorithms, complexity theory, graphs in models of computation, lower bounds, formal languages, unification, rewriting and type theory, distributed computation, concurrency, semantics, model checking, and formal calculi.

This book constitutes the refereed proceedings of the 14th International Symposium Fundamentals of Computation Theory, FCT 2003, held in Malmö, Sweden in August 2003. The 36 revised full papers presented together with an invited paper and the abstracts of 2 invited talks were carefully reviewed and selected from 73 submissions. The papers are organized in topical sections on approximibility, algorithms, networks and complexity, computational biology, computational geometry, computational models and complexity, structural complexity, formal languages, and logic.