Table Of ContentJewels are Forever
Springer
Berlin
Heidelberg
New York
Barcelona
Hong Kong
London
Milan
Paris
Singapore
Tokyo
Arto Salomaa
Juhani Karhumaki • Hermann Maurer
Gheorghe Paun· Grzegorz Rozenberg (Eds.)
Jewels are Forever
Contributions on
Theoretical Computer Science
in Honor of Arto Salomaa
With 20 Figures
" Springer
Editors
Professor Dr. Juhani Karhumaki Dr. Gheorghe Paun
Department of Mathematics Institute of Mathematics
and Turku Centre for Computer Science Romanian Academy of Sciences
University of Turku PO Box 1-764
FIN-20014 Turku, Finland RO-70700 Bucharest, Romania
[email protected] [email protected]
Professor Dr. Hermann Maurer Professor Dr. Grzegorz Rozenberg
Institutes for Information Processing Department of Computer Science
and Computer Supported Media (IICM) Leiden University
Technical University of Graz PO Box 9512
Schiessstattgasse 4a 2300 RA Leiden, The Netherlands
A-SOlO Graz, Austria [email protected]
[email protected]
Frontispiece (p. 11): Digital photographic image
by Henrik Duncker and Yrjo Tuunanen, 1994,
©Media Lab, University of Art and Design Helsinki
Library of Congress Cataloging-in-Publication Data applied for
Die Deutsche Bibliothek - CIP-Einheitsaufnahme
Jewels are forever: contributions on theoretical computer science in
honor of Arto Salomaa/Juhani Karhumaki ... (ed.). -Berlin;
Heidelberg; New York; Barcelona; Hong Kong; London; Milan;
Paris; Singapore; Tokyo: Springer, 1999
ISBN-13:978-3-642-64304-0 e-ISBN-13:978-3-642-60207-8
DOl: 10.1007/978-3-642-60207-8
ISBN-13:978-3-642-64304-0 Springer-Vedag Berlin Heidelberg New York
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© Springer-Verlag Berlin Heidelberg 1999
Softcover reprint of the hardcover 1st edition 1999
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Preface
This volume is dedicated to Professor Arto Salomaa, a towering figure of
theoretical computer science, on the occasion of his 65th birthday. His sci
entific contributions and influence are enormous - we refer the reader to the
following Laudation for an account of his scientific achievements.
The book is a tribute to Arto by the theoretical computer science com
munity. It includes the contributions of many outstanding scientists, and it
covers most of Arto's many research areas. Due to its representative selection
of classic topics and cutting edge trends in theoretical computer science it
constitutes a comprehensive state-of-the-art survey.
We feel very honored that we have been given the opportunity to edit
this book - we also feel privileged to be his friends. We are indebted to
all contributors for paying tribute to Arto through this book. We thank Dr.
H. Wossner and Mrs. 1. Mayer from Springer-Verlag for a perfect cooperation
in producing this volume. Our special thanks go to Mr. M. Hirvensalo and
Mr. A. Lepisto, the "2nd generation Ph.D. students" of Arto, for their work
on this book.
Turku, April 1999 Juhani Karhumiiki
Hermann Maurer
Gheorghe Paun
Grzegorz Rozenberg
Contents
Laudation for Arto Salomaa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. XI
Bibliography of Arto Salomaa ............................... XIII
Part I. Automata I: Finite State Machines
Semilattices of Fault Semiautomata. . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Janusz A. Brzozowski, Helmut Jurgensen
Thompson Languages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 16
Dora Giammarresi, Jean-Luc Ponty, Derick Wood
On Some Special Classes of Regular Languages . . . . . . . . . . . . . .. 25
BalO.zs Imreh, Masami Ito
Synchronized Shuffle and Regular Languages ................. 35
Michel Latteux, Yves Roos
Synchronization Expressions:
Characterization Results and Implementation ................ 45
Kai Salomaa, Sheng Yu
Part II. Automata II: More General Devices
Uniformization of Rational Relations. ..... . . .. . . .. . . ......... 59
Christian ChojJrut, Serge Grigorieff
Tree-Walking Pebble Automata. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 72
Joost Engelfriet, Hendrik Jan Hoogeboom
Counter Machines: Decision Problems and Applications ...... 84
Oscar H. Ibarra, Jianwen Su
On the Equivalence of Finite Substitutions and Transducers .. 97
Juhani K arhumiiki, Leonid P. Lisovik
VIII Contents
Complementation of Biichl Automata Revisited .............. 109
Wolfgang Thomas
Part III. Automata with Multiplicities
Languages Accepted by Integer Weighted Finite Automata ... 123
Vesa Halava, Tero Harju
A Power Series Approach to Bounded Languages ............. 135
Juha Honkala
Full Abstract Families of Tree Series I ........................ 145
Werner Kuich
Linear Automata, Rational Series
and a Theorem of Fine and Wilf .............................. 157
Giovanna Melideo, Cesidia Pasquarelli, Stefano Varricchio
Part IV. Formal Languages
Numerical Parameters of Evolutionary Grammars . . . . . . . . . . .. 171
Jurgen Dassow
Iterated GSM Mappings: A Collapsing Hierarchy ............. 182
Vincenzo Manca, Carlos Martin-Vide, Gheorghe Paun
On the Length of Words ...................................... 194
Solomon Marcus
An Insertion into the Chomsky Hierarchy? ................... 204
Robert McNaughton
Word Length Controlled DTOL Systems
and Slender Languages ........................... , ...... " ... 213
Taishin Yasunobu Nishida
Part V. Algorithms and Complexity
Program-Size Complexity of Initial Segments
and Domination Reducibility ................................. 225
Cristian S. Calude, Richard J. Coles
Stability of Approximation Algorithms
and the Knapsack Problem ................................... 238
Juraj Hromkovic
Contents IX
Some Examples of Average-case Analysis
by the Incompressibility Method ............................. 250
Tao Jiang, Ming Li, Paul Vittlnyi
Complexity of Language Recognition
Problems for Compressed Words ............................. 262
Wojciech Plandowski, Wojciech Rytter
Algorithms on Continued Fractions .......................... 273
Octavian Soldea, Azaria Paz
Part VI. Combinatorics of Words
On the Index of Sturmian Words ............................. 287
Jean Berstel
Repetitions and Boxes in Words and Pictures ................ 295
Arturo Carpi, Aldo de Luca
Small Aperiodic Sets of Triangular and Hexagonal Tiles ...... 307
Karel CuZik II
Quadratic Word Equations ................................... 314
Volker Diekert, John Michael Robson
Fair and Associative Infinite Trajectories ..................... 327
Alexandru Mateescu, George Daniel Mateescu
Forbidden Factors in Finite and Infinite Words . . . . . . . . . . . . . . . 339
Filippo Mignosi, Antonio Restivo, Marinella Sciortino
Part VII. Novel Directions
Reversible :tyIolecular Computation in Ciliates ................ 353
Lila Kari, Jarkko Kari, Laura F. Landweber
Logic, Probability, and Rough Sets ........................... 364
Zdzislaw Pawlak
List of Contributors .......................................... 375
Laudation for Arto Salomaa
Arto Kustaa Salomaa was born in Turku, Finland, on June 6, 1934. He pub
lished his first paper in 1959, and since then he has published about 300
papers and 11 books, and has edited 15 books - see the following Bibliogra
phy. He has had enormous influence on theoretical computer science and is
certainly one of the founding fathers of formal language and automata theory.
His influence on theoretical computer science extends far beyond his writ
ings. He has supervised 24 Ph.D. students in Finland, Denmark and Canada,
and many of them have become top scientists in various areas of computer
science.
He is on the editorial board of some fifteen international journals and
book series and has been a member of program committees for almost all
important conferences in theoretical computer science in Europe.
Arto is a very stimulating colleague, and he has cooperated with many
scientists allover the world - his list of co-authors includes some 53 names.
His contributions to theoretical computer science have been recognized
in many ways. He must be one of the most decorated computer scientists -
he has been awarded six Honorary Doctorates (in four countries) and has
received many scientific awards. He is a member of Academia Europaea, the
Academy of Sciences of Finland, and the Hungarian Academy of Sciences.
He was the President of the European Association for Theoretical Computer
Science (EATCS) from 1979 until 1986, and had an enormous influence on
this organisation through many other functions. Some of the honors he has
received are quite unusual. On one of his trips a Maori group north of Auck
land put on a Powhiri, a ceremony usually conducted as a way of honoring
persons of the importance of the Queen of England. Arto may well be the
only computer scientist to whom such a tribute has ever been paid.
From all the facts listed above it must be clear that in celebrating Arto's
65th birthday we pay tribute to a towering figure of theoretical computer
science. There is no doubt that theoretical computer science owes a lot to
Arto Salomaa.
Throughout his scientific career Arto has had many offers from top uni
versities allover the world. However, he has decided that Turku is his home
town and that this is where he wants to have his base. He received his Master
of Science from the University of Turku in 1956, and although he did his grad-
XII Laudation for Arto Salomaa
uate studies in Berkeley, he defended his Ph.D. at the University of Turku
in 1960. He became a full professor at Turku University in 1966. Since then
he has made Thrku a real place of excellence in theoretical computer science,
and certainly the world capital in formal language and automata theory.
Although Thrku was always his home base, he has traveled extensively. He
spent long periods of time at the universities of Western Ontario and Waterloo
in Canada and the University of Aarhus in Denmark. He has also had quite
lengthy research stays, among others, at the universities of Auckland, Graz,
Karlsruhe, Leiden, Szeged, and Vienna.
He has lectured at more than 150 universities and research centers all
over the world - he is a very inspiring lecturer. His lectures and his books
demonstrate a unique ability: he is always able to pick out from the sea of
results the real jewels, and then present them in the way that jewels deserve
(quite often the jewels are also created by him). As a matter offact, one of his
most frequently cited books is "Jewels of Formal Language Theory". That's
why we thought that the title "Jewels are Forever" fits this book very well.
Thrku, April 1999 Juhani Karhumiiki
Hermann Maurer
Gheorghe Piiun
Grzegorz Rozenberg
