International Federation for Information Processing The IFIP series publishes state-of-the-art results in the sciences and technologies of information and communication. The scope of the series includes: foundations of computer science; software theory and practice; education; computer applications in technology; communication systems; systems modeling and optimization; information systems; computers and society; computer systems technology; security and protection in information processing systems; artificial intelligence; and human-computer interaction. Proceedings and post-proceedings of refereed international conferences in computer science and interdisciplinary fields are featured. These results often precede journal publication and represent the most current research. The principal aim of the IFIP series is to encourage education and the dissemination and exchange of information about all aspects of computing. For more information about the 300 other books in the IFIP series, please visit www.springer.com. For more information about IFIP, please visit www.ifip.org.

International Federation for Information Processing The IFIP series publishes state-of-the-art results in the sciences and technologies of information and communication. The scope of the series includes: foundations of computer science; software theory and practice; education; computer applications in technology; communication systems; systems modeling and optimization; information systems; computers and society; computer systems technology; security and protection in information processing systems; artificial intelligence; and human-computer interaction. Proceedings and post-proceedings of refereed international conferences in computer science and interdisciplinary fields are featured. These results often precede journal publication and represent the most current research. The principal aim of the IFIP series is to encourage education and the dissemination and exchange of information about all aspects of computing. For more information about the 300 other books in the IFIP series, please visit www.springer.com. For more information about IFIP, please visit www.ifip.org.

This book constitutes the refereed proceedings of the 16th International Conference on Descriptional Complexity of Formal Systems, DCFS 2014, held in Turku, Finland, in August 2014. The 27 full papers presented were carefully reviewed and selected from 35 submissions. The conference dealt with the following topics: Automata, grammars, languages and other formal systems; various modes of operation and complexity measures; trade-offs between computational models and modes of operation; succinctness of description of objects, state explosion-like phenomena; circuit complexity of Boolean functions and related measures; resource-bounded or structure-bounded environments; frontiers between decidability and undecidability; universality and reversibility; structural complexity; formal systems for applications (e.g., software reliability, software and hardware testing, modeling of natural languages); nature-motivated (bio-inspired) architectures and unconventional models of computing; complexity aspects of combinatorics on words; Kolmogorov complexity.

This Festschrift celebrates the 70th birthday of Arto Kustaa Salomaa (born in Turku, Finland on June 6, 1934), one of the most in?uential researchers in theoretical computer science. Most ofhis researchconcernstheory - he is one of the founding fathers of formal language and automata theory, but he has also made important contributions to cryptography and natural computing. His approach to research in theoretical computer science is exemplary and inspirational for his students, collaborators, andthereadersofhispapersandbooks. Forhim,theroleoftheory(incomputer science) is to discover general rules of information processing that hold within computer science and in the world around us. One should not waste time on research concerning passing artifacts (or fashionable topics of the moment) in computer science - theory should be permanently predictive, insightful, and inspiring. That's why we chose the title "Theory is Forever". The main source of his in?uence on theoretical computer science is his publi- tions. Arto is a born writer - his papers and books are always most elegant.He has a unique gift for identifying the real essence of a research problem, and then presenting it in an incisive and eloquent way. He can write about a very involved formal topic and yet avoid a (much too common) overformalization. Many of his writings are genuine jewels and belong to the classics of theoreticalcomputer science. Theyhaveinspiredgenerationsofstudentsandresearchers. Indeed,even computers as well as computer science have learned a lot from Arto's publi- tions - this is nicely illustrated by DADARA on the cover of this volume.

The 31st International Colloquium on Automata, Languages, and Programming (ICALP 2004) was held from July 12 to July 16 in Turku, Finland. This volume contains all contributed papers presented at ICALP 2004, together with the invitedlecturesbyPhilippeFlajolet(INRIA),RobertHarper(CarnegieMellon), Monika Henzinger (Google), Martin Hofmann (Munich), Alexander Razborov (Princeton and Moscow), Wojciech Rytter (Warsaw and NJIT), and Mihalis Yannakakis (Stanford). ICALP is a series of annual conferences of the European Association for Theoretical Computer Science (EATCS). The ?rst ICALP took place in 1972 and the ICALP program currently consists of track A (focusing on algorithms, automata, complexity, and cryptography) and track B (focusing on databases, logics, semantics, and principles of programming). Inresponsetothecallforpapers,theprogramcommitteereceived379papers, 272 for track A and 107 for track B. This is the highest number of submitted papersinthehistoryofICALPconferences.Theprogramcommitteesselected97 papersforinclusionintothescienti?cprogram.Theprogramcommitteefortrack A met on March 27 and 28 in Barcelona and selected 69 papers from track A.TheprogramcommitteefortrackBselected28papersfromtrackBinthecourse of an electronic discussion lasting for two weeks in the second half of March. The selections were based on originality, quality, and relevance to theor- ical computer science. We wish to thank all authors who submitted extended abstracts for consideration, the program committee for its hard work, and all referees who assisted the program committee in the evaluation process.

This book constitutes the thoroughly refereed post-proceedings of the 5th International Workshop on Finite-State Methods in Natural Language Processing, FSMNLP 2005, held in Helsinki, Finland, September 2005. The book presents 24 revised full papers and seven revised poster papers together with two invited contributions and abstracts of six software demos. Topics include morphology, optimality theory, some special FSM families, weighted FSM algorithms, FSM representations, exploration, ordered structures, and surface parsing.

This book presents state of the art research in theoretical computer science and related ?elds. In particular, the following areas are discussed: automata theory, formal languages and combinatorics of words, graph transformations, Petri nets, concurrency, as well as natural and molecular computing. The articles are written by leading researchers in these areas. The writers were originally invited to contribute to this book but then the normal refereeing procedure was applied as well. All of the articles deal with some issue that has been under vigorous study during recent years. Still, the topics range from very classical ones to issues raised only two or three years ago. Both survey articles and papers attacking speci?c research problems are included. The book highlights some key issues of theoretical computer science, as they seem to us now at the beginning of the new millennium. Being a comprehensive overview of some of the most active current research in theoretical computer science, it should be of de?nite interest for all researchers in the areas covered. The topics range from basic decidability and the notion of information to graph grammars and graph transformations, and from trees and traces to aqueous algorithms, DNA encoding and self-assembly. Special e?ort has been given to lucid presentation. Therefore, the book should be of interest also for advanced students.

This book constitutes the refereed proceedings of the 11th International Conference on Developments in Language Theory, DLT 2007, held in Turku, Finland in July 2007. It addresses all important issues in language theory including grammars, acceptors and transducers for words, trees and graphs; algebraic theories of automata; relationships to cryptography, concurrency, complexity theory and logic; bioinspired computing, and quantum computing.

This book constitutes the refereed proceedings of the 34th Conference on Current Trends in Theory and Practice of Computer Science, SOFSEM 2008, held in Slovakia, in 2008. The 57 revised full papers, presented together with 10 invited contributions, were carefully reviewed and selected from 162 submissions. The contributions are segmented into four topical sections on foundations of computer science; computing by nature; networks, security, and cryptography; and Web technologies.

This book constitutes the proceedings of the 7th International Computer Science Symposium in Russia, CSR 2012, held in Nizhny Novgorod in July 2012. The 28 full papers presented in this volume were carefully reviewed and selected from 66 submissions. CSR 2012 was one of the events of the Alan Turing Year 2012, the topics dealt with cover substantial parts of theoretical computer science and its applications.

This book constitutes the refereed proceedings of the 9th International Conference on Combinatorics on Words, WORDS 2013, held in Turku, Finland, in September 2013 under the auspices of the EATCS. The 20 revised full papers presented were carefully reviewed and selected from 43 initial submissions. The central topic of the conference is combinatorics on words (i.e. the study of finite and infinite sequence of symbols) from varying points of view, including their combinatorial, algebraic and algorithmic aspects, as well as their applications.

International Federation for Information Processing The IFIP series publishes state-of-the-art results in the sciences and technologies of information and communication. The scope of the series includes: foundations of computer science; software theory and practice; education; computer applications in technology; communication systems; systems modeling and optimization; information systems; computers and society; computer systems technology; security and protection in information processing systems; artificial intelligence; and human-computer interaction. Proceedings and post-proceedings of refereed international conferences in computer science and interdisciplinary fields are featured. These results often precede journal publication and represent the most current research. The principal aim of the IFIP series is to encourage education and the dissemination and exchange of information about all aspects of computing. For more information about the 300 other books in the IFIP series, please visit www.springer.com. For more information about IFIP, please visit www.ifip.org.

International Federation for Information Processing The IFIP series publishes state-of-the-art results in the sciences and technologies of information and communication. The scope of the series includes: foundations of computer science; software theory and practice; education; computer applications in technology; communication systems; systems modeling and optimization; information systems; computers and society; computer systems technology; security and protection in information processing systems; artificial intelligence; and human-computer interaction. Proceedings and post-proceedings of refereed international conferences in computer science and interdisciplinary fields are featured. These results often precede journal publication and represent the most current research. The principal aim of the IFIP series is to encourage education and the dissemination and exchange of information about all aspects of computing. For more information about the 300 other books in the IFIP series, please visit www.springer.com. For more information about IFIP, please visit www.ifip.org.

This book constitutes the refereed proceedings of the 16th International Conference on Descriptional Complexity of Formal Systems, DCFS 2014, held in Turku, Finland, in August 2014. The 27 full papers presented were carefully reviewed and selected from 35 submissions. The conference dealt with the following topics: Automata, grammars, languages and other formal systems; various modes of operation and complexity measures; trade-offs between computational models and modes of operation; succinctness of description of objects, state explosion-like phenomena; circuit complexity of Boolean functions and related measures; resource-bounded or structure-bounded environments; frontiers between decidability and undecidability; universality and reversibility; structural complexity; formal systems for applications (e.g., software reliability, software and hardware testing, modeling of natural languages); nature-motivated (bio-inspired) architectures and unconventional models of computing; complexity aspects of combinatorics on words; Kolmogorov complexity.

This Festschrift celebrates the 70th birthday of Arto Kustaa Salomaa (born in Turku, Finland on June 6, 1934), one of the most in?uential researchers in theoretical computer science. Most ofhis researchconcernstheory - he is one of the founding fathers of formal language and automata theory, but he has also made important contributions to cryptography and natural computing. His approach to research in theoretical computer science is exemplary and inspirational for his students, collaborators, andthereadersofhispapersandbooks. Forhim,theroleoftheory(incomputer science) is to discover general rules of information processing that hold within computer science and in the world around us. One should not waste time on research concerning passing artifacts (or fashionable topics of the moment) in computer science - theory should be permanently predictive, insightful, and inspiring. That's why we chose the title "Theory is Forever". The main source of his in?uence on theoretical computer science is his publi- tions. Arto is a born writer - his papers and books are always most elegant.He has a unique gift for identifying the real essence of a research problem, and then presenting it in an incisive and eloquent way. He can write about a very involved formal topic and yet avoid a (much too common) overformalization. Many of his writings are genuine jewels and belong to the classics of theoreticalcomputer science. Theyhaveinspiredgenerationsofstudentsandresearchers. Indeed,even computers as well as computer science have learned a lot from Arto's publi- tions - this is nicely illustrated by DADARA on the cover of this volume.

The 31st International Colloquium on Automata, Languages, and Programming (ICALP 2004) was held from July 12 to July 16 in Turku, Finland. This volume contains all contributed papers presented at ICALP 2004, together with the invitedlecturesbyPhilippeFlajolet(INRIA),RobertHarper(CarnegieMellon), Monika Henzinger (Google), Martin Hofmann (Munich), Alexander Razborov (Princeton and Moscow), Wojciech Rytter (Warsaw and NJIT), and Mihalis Yannakakis (Stanford). ICALP is a series of annual conferences of the European Association for Theoretical Computer Science (EATCS). The ?rst ICALP took place in 1972 and the ICALP program currently consists of track A (focusing on algorithms, automata, complexity, and cryptography) and track B (focusing on databases, logics, semantics, and principles of programming). Inresponsetothecallforpapers,theprogramcommitteereceived379papers, 272 for track A and 107 for track B. This is the highest number of submitted papersinthehistoryofICALPconferences.Theprogramcommitteesselected97 papersforinclusionintothescienti?cprogram.Theprogramcommitteefortrack A met on March 27 and 28 in Barcelona and selected 69 papers from track A.TheprogramcommitteefortrackBselected28papersfromtrackBinthecourse of an electronic discussion lasting for two weeks in the second half of March. The selections were based on originality, quality, and relevance to theor- ical computer science. We wish to thank all authors who submitted extended abstracts for consideration, the program committee for its hard work, and all referees who assisted the program committee in the evaluation process.

This book constitutes the thoroughly refereed post-proceedings of the 5th International Workshop on Finite-State Methods in Natural Language Processing, FSMNLP 2005, held in Helsinki, Finland, September 2005. The book presents 24 revised full papers and seven revised poster papers together with two invited contributions and abstracts of six software demos. Topics include morphology, optimality theory, some special FSM families, weighted FSM algorithms, FSM representations, exploration, ordered structures, and surface parsing.

This book presents state of the art research in theoretical computer science and related ?elds. In particular, the following areas are discussed: automata theory, formal languages and combinatorics of words, graph transformations, Petri nets, concurrency, as well as natural and molecular computing. The articles are written by leading researchers in these areas. The writers were originally invited to contribute to this book but then the normal refereeing procedure was applied as well. All of the articles deal with some issue that has been under vigorous study during recent years. Still, the topics range from very classical ones to issues raised only two or three years ago. Both survey articles and papers attacking speci?c research problems are included. The book highlights some key issues of theoretical computer science, as they seem to us now at the beginning of the new millennium. Being a comprehensive overview of some of the most active current research in theoretical computer science, it should be of de?nite interest for all researchers in the areas covered. The topics range from basic decidability and the notion of information to graph grammars and graph transformations, and from trees and traces to aqueous algorithms, DNA encoding and self-assembly. Special e?ort has been given to lucid presentation. Therefore, the book should be of interest also for advanced students.

This book constitutes the refereed proceedings of the 11th International Conference on Developments in Language Theory, DLT 2007, held in Turku, Finland in July 2007. It addresses all important issues in language theory including grammars, acceptors and transducers for words, trees and graphs; algebraic theories of automata; relationships to cryptography, concurrency, complexity theory and logic; bioinspired computing, and quantum computing.

This book constitutes the refereed proceedings of the 34th Conference on Current Trends in Theory and Practice of Computer Science, SOFSEM 2008, held in Slovakia, in 2008. The 57 revised full papers, presented together with 10 invited contributions, were carefully reviewed and selected from 162 submissions. The contributions are segmented into four topical sections on foundations of computer science; computing by nature; networks, security, and cryptography; and Web technologies.

This book constitutes the proceedings of the 7th International Computer Science Symposium in Russia, CSR 2012, held in Nizhny Novgorod in July 2012. The 28 full papers presented in this volume were carefully reviewed and selected from 66 submissions. CSR 2012 was one of the events of the Alan Turing Year 2012, the topics dealt with cover substantial parts of theoretical computer science and its applications.

This book constitutes the refereed proceedings of the 9th International Conference on Combinatorics on Words, WORDS 2013, held in Turku, Finland, in September 2013 under the auspices of the EATCS. The 20 revised full papers presented were carefully reviewed and selected from 43 initial submissions. The central topic of the conference is combinatorics on words (i.e. the study of finite and infinite sequence of symbols) from varying points of view, including their combinatorial, algebraic and algorithmic aspects, as well as their applications.