The first volume of the book Informatikai algoritmusok appeared in 2004 in Hungarian [ 127 ], and the second volume of the book appeared in 2005 [ 128 ]. Two volumes contained 31 chapters: 23 chapters of the first and second volumes of the present electronic book, and further chapters on clustering, frequent elements in data bases, geoinformatics, inner-point methods, number theory, Petri-nets, queuing theory, and scheduling.

The Hungarian version of the first volume contains those chapters which were finished until May of 2004, and the second volume contains the chapters finished until April of 2005.

The printed English version contains the chapters submitted until April of 2007. Volume 1 [ 129 ] contains the chapters belonging to the fundamentals of informatics, while the second volume [ 130 ] contains the chapters having closer connection with some applications.

The first and second volumes of the given book represent an extended and corrected electronic version of the printed book written is English. The third volume of the present book contains new chapters.

The chapters of the first volume are divided into three parts. The chapters of Part 1 are connected with automata: Automata and Formal Languages (written by Zoltán Kása, Sapientia Hungarian University of Transylvania), Compilers (Zoltán Csörnyei, Eötvös Loránd University), Compression and Decompression (Ulrich Tamm, Chemnitz University of Technology Commitment), Reliable Computations (Péter Gács, Boston University).

The chapters of Part 2 have algebraic character: here are the chapters Algebra (written by Gábor Ivanyos and Lajos Rónyai, Budapest University of Technology and Economics), Computer Algebra (Antal Járai and Attila Kovács, Eötvös Loránd University), further Cryptology and Complexity Theory (Jörg Rothe, Heinrich Heine University).

The chapters of the third part have numeric character: Competitive Analysis (Csanád Imreh, University of Szeged), Game Theory (Ferenc Szidarovszky, The University of Arizona) and Scientific Computations (Aurél Galántai, Óbuda University and András Jeney, University of Miskolc).

The second volume is also divided into three parts. The chapters of Part 4 are connected with computer networks: Distributed Algorithms (Burkhard Englert, California State University; Dariusz Kowalski, University of Liverpool; Grzegorz Malewicz, University of Alabama; Alexander Allister Shvartsman, University of Connecticut), Parallel Algorithms (Claudia Fohry, University of Kassel and Antal Iványi, Eötvös Loránd University), Network Simulation (Tibor Gyires, Illinois State University) and Systolic Systems (Eberhard Zehendner, Friedrich Schiller University).

The chapters of Part 5 are Relational Databases and Query in Relational Databases (János Demetrovics, Eötvös Loránd University and Attila Sali, Alfréd Rényi Institute of Mathematics), Semistructured Data Bases (Attila Kiss, Eötvös Loránd University) and Memory Management (Ádám Balogh, Antal Iványi, Eötvös Loránd University).

The chapters of the third part of the second volume have close connections with biology: Bioinformatics (István Miklós, Rényi Institute of Mathematics), Human-Computer Interactions (Ingo Althöfer, Stefan Schwarz, Friedrich Schiller University), and Computer Graphics (László Szirmay-Kalos, Budapest University of Technology and Economics).

The chapters are validated by Gábor Ivanyos, István Majzik, Lajos Rónyai, András Recski, and Tamás Szántai (Budapest University of Technology and Economics), András Benczúr, Sándor Fridli, János Gonda, István Katsányi, Attila Kiss, László Varga, János Vida, and Béla Vizvári (Eötvös Loránd University), Dezső Sima (Óbuda University) Pál Dömösi, János Sztrik, and Attila Pethő (University of Debrecen), Zoltán Fülöp (University of Szeged), Anna Gál (University of Texas), János Mayer (University of Zürich).

The first and second volumes contain verbal description, pseudocode and analysis of over 200 algorithms, and over 350 figures and 120 examples illustrating how the algorithms work. Each section ends with exercises and each chapter ends with problems. In the two volumes you can find over 330 exercises and 70 problems.

We have supplied an extensive bibliography, in the section Chapter Notes of each chapter. In the bibliography the names of the authors, journals and publishers are usually active links to the corresponding web sites (the living elements are underlined in the printed version and on the screen too).

The LaTeX style file was written by Viktor Belényesi, Zoltán Csörnyei, László Domoszlai and Antal Iványi. The figures was drawn or corrected by Kornél Locher. Anna Iványi transformed the bibliography into hypertext. The DOCBOOK version was made by Marton 2001 Kft.

Using the data of the colofon page you can contact with any of the creators of the book. We welcome ideas for new exercises and problems, and also critical remarks or bug reports.

The publication of the printed book was supported by Department of Mathematics of Hungarian Academy of Science, and the electronic version received support from European Union and from the European Social Fund.

Budapest, June 22, 2011

Antal Iványi (