The Computational Complexity Of Equivalence And Isomorphism Problems

A computational model is a framework for doing computations according to certain specified rules on some input data. These models come for example from automata theory, formal language theory, logic, or circuit theory. The computational power of such a model can be judged by evaluating certain problems with respect to that model. The theory of computations is the study of the inherent difficulty of computational problems, that is, their computational complexity. This monograph analyzes the computational complexity of the satisfiability, equivalence, and almost-equivalence problems with respect to various computational models. In particular, Boolean formulas, circuits, and various kinds of branching programs are considered.

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 volume contains the papers presented at the 30th Symposium on Mathematical Foundations of Computer Science (MFCS 2005) held in Gdansk, Poland from August 29th to September 2nd, 2005.

This book constitutes the refereed proceedings of the 21st Annual Symposium on Theoretical Aspects of Computer Science, STACS 2004, held in Montpellier, France, in March 2004. The 54 revised full papers presented together with two invited contributions were carefully reviewed and selected from more than 200 submissions. The papers are organized in topical sections on structural complexity, graph algorithms, quantum computing, satisfiability - constraint satisfaction problems, scheduling, algorithms, networks, automata theory and words, path algorithms, cryptography, logic and formal languages, game theory and complexity, and algorithmic information.

Modern cryptology increasingly employs mathematically rigorous concepts and methods from complexity theory. Conversely, current research topics in complexity theory are often motivated by questions and problems from cryptology. This book takes account of this situation, and therefore its subject is what may be dubbed "cryptocomplexity'', a kind of symbiosis of these two areas. This book is written for undergraduate and graduate students of computer science, mathematics, and engineering, and can be used for courses on complexity theory and cryptology, preferably by stressing their interrelation. Moreover, it may serve as a valuable source for researchers, teachers, and practitioners working in these fields. Starting from scratch, it works its way to the frontiers of current research in these fields and provides a detailed overview of their history and their current research topics and challenges.

This book constitutes the refereed proceedings of the 32nd International Symposium on Mathematical Foundations of Computer Science, MFCS 2007, held in Ceský Krumlov, Czech Republic, August 2007. The 61 revised full papers presented together with the full papers or abstracts of five invited talks address all current aspects in theoretical computer science and its mathematical foundations.

This book constitutes the refereed proceedings of the 22nd Annual Symposium on Theoretical Aspects of Computer Science, STACS 2005, held in Stuttgart, Germany in February 2005. The 54 revised full papers presented together with 3 invited papers were carefully reviewed and selected from 217 submissions. A broad variety of topics from theoretical computer science are addressed, in particular complexity theory, algorithmics, computational discrete mathematics, automata theory, combinatorial optimization and approximation, networking and graph theory, computational geometry, grammar systems and formal languages, etc.

This book offers the exchange of ideas between scientists and technicians from both the academic and industrial sector which is essential to facilitate the development of systems that can meet the ever-increasing demands of today’s society. The 18th International Symposium on Distributed Computing and Artificial Intelligence 2021 (DCAI 2021) is a forum to present the applications of innovative techniques for studying and solving complex problems in artificial intelligence and computing areas. The present edition brings together past experience, current work, and promising future trends associated with distributed computing, artificial intelligence, and their application in order to provide efficient solutions to real problems. This year’s technical program presents both high quality and diversity, with contributions in well-established and evolving areas of research. Specifically, 55 papers were submitted to main track and special sessions, by authors from 24 different countries, representing a truly “wide area network” of research activity. The DCAI’21 technical program has selected 21 papers, and, as in past editions, it will be special issues in ranked journals such as Electronics, Sensors, Systems, Robotics, Mathematical Biosciences and ADCAIJ. These special issues cover extended versions of the most highly regarded works. Moreover, DCAI'21 special sessions have been a very useful tool to complement the regular program with new or emerging topics of particular interest to the participating community.

This book constitutes the refereed proceedings of the 19th International Symposium on Fundamentals of Computation Theory, FCT 2013, held in Liverpool, UK, in August 2013. The 29 papers (26 full papers and 3 invited papers) were carefully reviewed and selected from 58 submissions. The papers cover the following topics: algorithms, formal methods, and emerging fields.

Recently, a variety ofresults on the complexitystatusofthegraph isomorphism problem has been obtained. These results belong to the so-called structural part of Complexity Theory. Our idea behind this book is to summarize such results which might otherwise not be easily accessible in the literature, and also, to give the reader an understanding of the aims and topics in Structural Complexity Theory, in general. The text is basically self contained; the only prerequisite for reading it is some elementary knowledge from Complexity Theory and Probability Theory. It can be used to teach a seminar or a monographic graduate course, but also parts of it (especially Chapter 1) provide a source of examples for a standard graduate course on Complexity Theory. Many people have helped us in different ways III the process of writing this book. Especially, we would like to thank V. Arvind, R.V. Book, E. May ordomo, and the referee who gave very constructive comments. This book project was especially made possible by a DAAD grant in the "Acciones In tegrada" program. The third author has been supported by the ESPRIT project ALCOM-II.