Alfredo Ferro Fabrizio Luccio Peter Widmayer (Eds.) Fun with LNCS 8496 Algorithms 7th International Conference, FUN 2014 Lipari Island, Sicily, Italy, July 1–3, 2014 Proceedings 123 Lecture Notes in Computer Science 8496 Commenced Publication in 1973 Founding and Former Series Editors: Gerhard Goos, Juris Hartmanis, and Jan van Leeuwen Editorial Board David Hutchison Lancaster University, UK Takeo Kanade Carnegie Mellon University, Pittsburgh, PA, USA Josef Kittler University of Surrey, Guildford, UK Jon M. Kleinberg Cornell University, Ithaca, NY, USA Alfred Kobsa University of California, Irvine, CA, USA Friedemann Mattern ETH Zurich, Switzerland John C. Mitchell Stanford University, CA, USA Moni Naor Weizmann Institute of Science, Rehovot, Israel Oscar Nierstrasz University of Bern, Switzerland C. Pandu Rangan Indian Institute of Technology, Madras, India Bernhard Steffen TU Dortmund University, Germany Demetri Terzopoulos University of California, Los Angeles, CA, USA Doug Tygar University of California, Berkeley, CA, USA Gerhard Weikum Max Planck Institute for Informatics, Saarbruecken, Germany Alfredo Ferro Fabrizio Luccio Peter Widmayer (Eds.) Fun with Algorithms 7th International Conference, FUN 2014 Lipari Island, Sicily, Italy, July 1-3, 2014 Proceedings 13 Volume Editors Alfredo Ferro Università degli Studi di Catania Dipartimento di Matematica e Informatica, Viale A. Doria 6, 95125 Catania, Italy E-mail: [email protected] Fabrizio Luccio Università di Pisa, Dipartimento di Informatica Largo B. Pontecorvo 3, 56127 Pisa, Italy E-mail: [email protected] Peter Widmayer ETH Zürich, Institute of Theoretical Computer Science Universitätsstrasse 6, 8092 Zürich, Switzerland E-mail: [email protected] ISSN 0302-9743 e-ISSN 1611-3349 ISBN 978-3-319-07889-2 e-ISBN 978-3-319-07890-8 DOI 10.1007/978-3-319-07890-8 Springer Cham Heidelberg New York Dordrecht London Library of Congress Control Number: 2014940050 LNCS Sublibrary: SL 1 – Theoretical Computer Science and General Issues © Springer International Publishing Switzerland 2014 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. Exempted from this legal reservation are brief excerpts in connection with reviews or scholarly analysis or material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Duplication of this publication or parts thereof is permitted only under the provisions of the Copyright Law of the Publisher’s location, in ist current version, and permission for use must always be obtained from Springer. Permissions for use may be obtained through RightsLink at the Copyright Clearance Center. Violations are liable to prosecution under the respective Copyright Law. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Typesetting: Camera-ready by author, data conversion by Scientific Publishing Services, Chennai, India Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com) Preface FUN with Algorithms is dedicated to the use, design, and analysis of algorithms and data structures, focusing on results that provide amusing, witty but nonethe- less original and scientifically profound contributions to the area. Donald Knuth’s famous quote captures this spirit nicely: .... pleasure has probably been the main goal all along. But I hesitate to admit it, because computer scientists want to maintain their image as hard-working individuals who deserve high salaries. Sooner or later society will realise that certain kinds of hard work are in fact admirable even though they are more fun than just about anything else.” The previous FUNs were held in Elba Island, Italy; in Castiglioncello, Tuscany, Italy; in Ischia Island, Italy; and in San Servolo Island, Venice, Italy. Special issues of Theoretical Computer Science, Discrete Applied Mathematics,andTheory of Computing Systems were dedicated to them. This volume contains the papers presented at the 7th International Con- ference on Fun with Algorithms 2014 that was held during July 1–3, 2014, on Lipari Island, Italy. The call for papers attracted 49 submissions from all over the world, addressing a wide variety of topics, including algorithmic questions rooted in biology, cryptography, game theory, graphs, the Internet, robotics and mobil- ity, combinatorics, geometry, stringology, as well as space-conscious, randomized, parallel, distributed algorithms, and their visualization. Each submission was re- viewed by three Program Committee members. After a careful reviewing process and a thorough discussion, the committee decided to accept 29 papers. In addi- tion, the program featured two invited talks by Paolo Boldi and Erik Demaine. Extended versions of selected papers will appear in a special issue of the journal Theoretical Computer Science. We thank all authors who submitted their work to FUN 2014, all Program Committee members for their expert assessments and the ensuing discussions, all external reviewers for their kind help, and Alfredo Ferro, Rosalba Giugno, Alfredo Pulvirenti as well as Giuseppe Prencipe for the organization of the con- ference and everything around it. We used EasyChair (http://www.easychair.org/) throughout the entire preparation of the conference, for handling submissions, reviews, the selection of papers, and the production of this volume. It greatly facilitated the whole pro- cess. We want to warmly thank the people who designed it and those who main- tain it. Warm thanks also go to Alfred Hofmann and Ingrid Haas at VI Preface Springer with whom collaborating was a pleasure. We gratefully acknowledge financial support by the Department of Computer Science of ETH Zurich, and the patronage of the European Association for Theoretical Computer Science (EATCS). April 2014 Alfredo Ferro Fabrizio Luccio Peter Widmayer Organization Program Committee J´er´emie Chalopin LIF, CNRS, Aix Marseille Universit´e, France Pierluigi Crescenzi Florence University, Italy Shantanu Das Aix-Marseille Universit´e, France Josep Diaz UPC Barcelona, Spain Yann Disser TU Berlin, Germany Paolo Ferragina University of Pisa, Italy Fedor Fomin University of Bergen, Norway Pierre Fraigniaud Universit´e Paris Diderot, France Leszek Gasieniec University of Liverpool, UK Fabrizio Grandoni IDSIA, University of Lugano, Switzerland Evangelos Kranakis Carleton University, Canada Danny Krizanc Wesleyan University, USA Flaminia Luccio Ca’ Foscari University of Venice, Italy Matus Mihalak ETH Zurich, Switzerland Linda Pagli University of Pisa, Italy David Peleg The Weizmann Institute, Israel Paolo Penna Universit`adiSalerno,Italy Giuseppe Persiano Universit`adiSalerno,Italy Giuseppe Prencipe University of Pisa, Italy Jose Rolim University of Geneva, Switzerland Piotr Sankowski University of Warsaw, Poland Ryuhei Uehara Japan Advanced Institute of Science and Technology Jorge Urrutia Universidad Nacional Aut´onoma de M´exico Peter Widmayer ETH Zurich, Switzerland Christos Zaroliagis Computer Technology Institute, University of Patras, Greece Additional Reviewers Bernasconi, Anna Donati, Beatrice Bonnet, Edouard Drange, Paal Groenaas Borassi, Michele Ferraioli, Diodato Cicalese, Ferdinando Focardi, Riccardo Cou¨etoux, Basile Fotakis, Dimitris De Prisco, Roberto Gallopoulos, Efstratios Di Luna, Giuseppe Antonio Giotis, Ioannis VIII Organization Kontogiannis, Spyros Poupet, Victor Labourel, Arnaud Rossi, Gianluca Luccio, Fabrizio Ruj, Sushmita Mamageishvili, Akaki Sacomoto, Gustavo Marino, Andrea Serna, Maria Naves, Guyslain Squarcina, Marco Pallottino, Lucia Uznanski, Przemyslaw Pisanti, Nadia Venturini, Rossano Table of Contents Algorithmic Gems in the Data Miner’s Cave ......................... 1 Paolo Boldi Fun with Fonts: Algorithmic Typography ........................... 16 Erik D. Demaine and Martin L. Demaine Happy Edges: Threshold-Coloring of Regular Lattices................. 28 Muhammad Jawaherul Alam, Stephen G. Kobourov, Sergey Pupyrev, and Jackson Toeniskoetter Classic Nintendo Games Are (Computationally) Hard ................ 40 Greg Aloupis, Erik D. Demaine, Alan Guo, and Giovanni Viglietta On the Solvability of the Six Degrees of Kevin Bacon Game - A Faster Graph Diameter and Radius Computation Method ................... 52 Michele Borassi, Pierluigi Crescenzi, Michel Habib, Walter Kosters, Andrea Marino, and Frank Takes No Easy Puzzles: A Hardness Result for Jigsaw Puzzles ............... 64 Michael Brand Normal, Abby Normal, Prefix Normal .............................. 74 P´eter Burcsi, Gabriele Fici, Zsuzsanna Lipt´ak, Frank Ruskey,