A Quick Summary of the Field of Parameterized Complexity, 2012

A quick summary of the ﬁeld of Parameterized Complexity, 2012

Overview

Parameterized Complexity is a recent branch of computational complexity theory that provides a framework for a refined analysis of hard algorithmic problems. The big, important problems facing Planet Earth have structure with “secondary” measurements (parameters), apart from the primary measurement of overall input size, that significantly affect problem computational complexity. The central notion of fixed parameter tractability (FPT) is a generalization of polynomial-time based on confining any non-polynomial (typically exponential) complexity costs to a function only of these secondary measurements. Parameterized algorithms have strong connections to heuristics for NP-hard problems, and the multivariate approach allows more re- alistic modelling of real-world input distributions. The field is strongly interdisciplinary, with applications in massive parallel processing of huge data sets, bioinformatics, AI, computational social choice, ecology and other disciplines.

Online Resources

The Parameterized Complexity Wiki has a tremendous amount of information, including papers at conferences and journals and arXiv. http://www.fpt.wikidot.com The Parameterized Complexity Newsletter keeps the community informed about breakthrough results, awards, and other news. http://fpt.wikidot.com/fpt-news:the-parameterized-complexity-newsletter

Monographs

1. R. G. Downey, M. R. Fellows. Parameterized Complexity. Springer-Verlag, 1999. 2. J. Flum, M. Grohe. Parameterized Complexity Theory. Springer-Verlag, 2006. 3. R. Niedermeier. Invitation to Fixed-Parameter Algorithms. Oxford University Press, 2006.

Recent Special Issues and Surveys

“Exact and Parameterized Computation - Moderately Exponential and Parameterized Approxi- mation”. Manuscripts are solicited for a special issue of the journal Theoretical Computer Science (Vangelis Th. Paschos, Lamsade, University Dauphine, Guest Editor) 2012. “Exact and Parameterized Computation”. Special Issue of Algorithmica (Venkatesh Raman and Saket Saurabh, Guest Editors) 2011-2012. “Lower bound based on the Exponential Time Hypothesis”. Daniel Lokshtanov, Daniel Marx and Saket Saurabh, EATCS Bulletin, No. 105, 41–71, 2011.

1 “Confronting intractability via parameters”. Rodney G. Downey and Dimitrios M. Thilikos, Computer Science Review 5(4): 279-317 (2011). “Parameterized Complexity of Discrete Optimization”. Special Issue of the journal Discrete Opti- mization. (Mike Fellows, Fedor V. Fomin and Gregory Gutin, Guest Editors ) 8(1):1, 2011. “Towards Fully Multivariate Algorithmics: Some New Results and Directions in Parameter Ecol- ogy”. Michael R. Fellows. IWOCA 2009. “Fixed-Parameter Tractability and Parameterized Complexity Applied to Problems From Com- putational Social Choice”. C. Lindner and J. Rothe. Supplement In Mathematical Programming Glossary (A. Holder, Ed) INFORMS Computing Society, Oct 2008. The Computer Journal, Vol 1 and Vol 3, (Michael Fellows, Rod Downey and Michael Langston, Guest Editors). This two-volume special issue has over 17 survey papers on various areas of Parameterized Complexity, book reviews, and a preface by Mike Fellows. 2008. “Exact and Parameterized Computation.” Special Issue of Algorithmica (Jianer Chen, Guest Editor) 2008. “Invitation to data reduction and problem kernelization”. Jiong Guo and Rolf Niedermeier. ACM SIGACT News, 38(1):31-45, 2007. Theoretical Computer Science, Special Issue on “Parameterized Complexity”. (R. Downey, M. Langston and R. Niedermeier, Guest Editors) 351 (3) 2006.

Recent Milestones in Conference Proceedings

Proceedings of the 23rd SODA, 2012 • R. Chitnis, M. Hajiaghayi, D. Marx, Fixed-Parameter Tractability of Directed Multiway Cut Parameterized by the Size of the Cutset. • S. Kratsch, M. Wahlstr¨om, Compression via Matroids: A Randomized Polynomial Kernel for Odd Cycle Transversal. • H. Dell, D. Marx, Kernelization of Packing Problems. Proceedings of the 44th STOC, 2012 • M. Grohe, D. Marx, Structure Theorem and Isomorphism Test for Graphs with Excluded Topological Subgraphs. Proceedings of the 52nd FOCS, 2011 • M. Cygan, J. Nederlof, M. Pilipczuk, M. Pilipczuk, Johan M. M. van Rooij, J. O. Woj- taszczyk, Solving connectivity problems parameterized by treewidth in single exponential time. Proceedings of the 43rd STOC, 2011 • N. Bousquet, J. Daligault, S. Thomass´e, Multicut is FPT. • D. Marx, I. Razgon: Fixed-parameter tractability of multicut parameterized by the size of the cutset. Proceedings of the 21st SODA, 2010 • F. V. Fomin, D. Lokshtanov, S. Saurabh, D. M. Thilikos, Bidimensionality and Kernels. International Conference Series

(There are four conference/workshop series. The main conference is IPEC, in its 7th year.) (1) International Symposium on Parameterized and Exact Computation (IPEC) focuses on all aspects of parameterized complexity and algorithmics. Please see http://fpt.wikidot.com/ipec for IPEC History, Steering Committee, Awards. In 2013 we will hold the 8th IPEC collocated with ALGO which also hosts ESA,WABI,WAOA, ATMOS, and ALGOSENSORS, in Sophia An- tipolis, France. Previous IPECs have been held in Slovenia, Germany, India, Denmark, Canada, Switzerland and Norway. (2) Workshop on Kernelization (WorKer) focuses on kernelization. The 3rd WorKer took place in 2011 at the Vienna University of Technology, Austria following successful workshops in Bergen 2009 and Leiden 2010. (3) Approximation, Parameterized and Exact Algorithms (APEX) is supported by the French National Agency for Research (ANR). APEX is co-located with STACS 2012 in Paris. (4) Workshop on Applications of Parameterized Algorithms and Complexity (APAC). APAC 2012 is collocated with ICALP in Warwick, UK.

Dagstuhl Seminars

Dagstuhl is the is the world’s premier venue for informatics. 2012 Seminar 12241, 10.06.12-15.06.12. Data Reduction and Problem Kernels. Dedicated to the occasion of the 60th birthday of Michael Fellows. Takes the place of WorKer 2012. 2009 Seminar 09511, 13.12.09 - 17.12.09 Parameterized complexity and approximation algorithms. Erik Demaine (MIT - Cambridge, US), MohammadTaghi HajiAghayi (AT&T Research - Florham Park, US), Daniel Marx (Budapest Univ. of Technology and Economics, HU). 2009 Seminar 09171, 19.04.09 - 24.04.09. Adaptive, Output Sensitive, Online and Parameterized Algorithms. Jérémy Barbay (DCC - Univ de Chile), Rolf Klein (Universität Bonn, DE), Alejan- dro Lopez-Ortiz (University of Waterloo, CA), Rolf Niedermeier (Universität Jena, DE). 2007 Seminar 07281, 08.07.07 - 13.07.07. Structure Theory and FPT Algorithmics for Graphs, Digraphs and Hypergraphs. Erik Demaine (MIT - Cambridge, US), Gregory Z. Gutin (RHUL - London, GB), Daniel Marx (Budapest Univ. of Technology and Economics, HU), Ulrike Stege (University of Victoria, CA). 2005 Seminar 05301, 24.07.05 - 29.07.05. Exact Algorithms and Fixed-Parameter Tractability. R. Downey (Univ. of Wellington, NZ), M. Grohe (HU Berlin, DE), M. Hallett (McGill Univ., CA), G. Woeginger (Univ. of Twente, NL). 2003 Seminar 03311, 27.07.03 - 01.08.03. Fixed Parameter Algorithms. M. Fellows (Univ. of Newcastle, AUS), M. Hallett (McGill Univ. of Montreal, CDN), R. Niedermeier (Univ. Tübingen,), N. Nishimura (Univ. of Waterloo, CDN). 2001 Seminar 01311, 29.07.01 - 03.08.01. Parameterized Complexity. R. Downey (Wellington), M. Fellows (Victoria), R. Niedermeier (Tübingen), P. Rossmanith (TU München).

Other workshops

(Listed are only a few of the many schools, tutorials and small workshops.) 2012 Parameterized Complexity - Multivariate Complexity Analysis Tutorial at CATS (Comput- ing: Australasian Theory Symposium) (ACSW Week), 3 Feb, Melbourne. 2011 Bergen Treewidth Workshop May 19-20, 2011. 2011 Parameterized Complexity: Not About Graphs! August Workshop at Charles Darwin Univ, Australia. The workshop aim is to identify important problems in new directions (control theory, automata, number theory, robotics, game theory, computational physics, etc.) to investigate within the parameterized framework. 2010 Parameterized Complexity of Computational Reasoning. Satellite event of the federated MFCS and CSL, organized by Stefan Szeider and Stefan Woltran. Aug 2010 in Brno, Czech Republic. 2010 Graph Decomposition: Theoretical, Algorithmic and Logical Aspects. Workshop held Oct 2010 at CIRM, Luminy, supported by French ANR projects GRAAL and AGAPE. 2010 Workshop on Parameterized Complexity, March 2010 at Univ Newcastle, Australia. 2010 Winter School at KAIST, S. Korea. Introduction to Parameterized Complexity by Sangil Oum ( http://www.mathnet.or.kr/real/2010/01/OumSangil(0112).pdf) 2010 Mathematical and Computational Methods in the Social Sciences. Workshop at the Univ. Auckland Centre for Algorithmic Aspects of Game Theory and Social Choice, a joint Centre between Economics, Mathematics and Computer Science, Arkadii Slinko, Director. 2009 AGAPE Spring School on Parameterized Complexity, May 2009, Corsica. 2009 Introduction to Graph and Geometric Algorithms workshop held at IISc Bangalore. 2009 Graph Decompositions and Algorithms (GRAAL), Montpellier, France. 2009 Chinese University of Hong Kong seminars on Parameterized Complexity organized by Prof. Leizhen Cai. 2008 National Chung Cheng Univ, National Tsing Hua Univ, National Dong Hwa Univ, and Academia Sinica, Taipei, Taiwan. Workshops with Rolf Niedermeier and Peter Rossmanith. 2008 International Summer School on Fixed Parameter Algorithms, Fudan University, Shanghai, Satellite event to AAIM’08. Organized by Prof. Rudolf Fleischer. 2008 Parameterized Complexity workshop as Satellite event to International Summer School in Formal Languages and Applications, organized by Prof. Joerg Flum (Freiburg). 2008 “Mini-Symposium: Intractability and Cognitive Modelling: Part 2 - Formalization of Ana- logical Structure Mapping,” organized by M. Muller, I. van Rooij and Todd Wareham, Nijmegen Institute for Cognition and Information (NICI), Radboud University Nijmegen, Nijmegen, the Netherlands. 2008 “Approximating Solution Structure,” organized by M. Hamilton, M. Muller, and I. van Rooij and Todd Wareham, Dept of Computer Science, Memorial Univ of Newfoundland.

Awards

(These are only those reported to Frances Rosamond, newsletter Editor.) 2012 European Research Council Starting Grant, beginning January 2012. The 1.15M EUR, 5-year project will start January 2012 in Budapest, Hungary. The project is “PARAMTIGHT: Parameterized complexity and the search for tight complexity results”. Awarded to Daniel Marx. 2011 Australian Research Council Discovery Early Career Researcher Award (DECRA) and the prestigious University of New South Wales (UNSW) Vice-Chancellor Award awarded to Serge Gaspers, Vienna Univ of Technology. Serge will move to Australia to work with Toby Walsh. 2011 Office of Naval Research (ONR) Young Investigator Award, an NSF CAREER Award, and a Google Faculty Research Award with total more than 1M dollars awarded to Mohammad Taghi Hajiaghayi, the University of Maryland. 2011 Junior Institute Universitaire de France was awarded to Cristina Bazgan, LAMSADE and University Dauphine, Paris. 2011 Spirit of Inquiry Award, DePaul Univ, Chicago in recognition for his research in theoretical computer science, especially in the area of parameterized complexity was awarded to Iyad Kanj. 2011 Australian Research Council Discovery Project, “Algorithmic engineering and complexity analysis of protocols for consensus”, 250,000 AUD over 2011-2013, awarded to Vlad Estivil-Castro (Griffith Univ), Mike Fellows, Frances Rosamond. (Charles Darwin Univ, AU). 2011 Czech Republic 3-year Science Research Award to Petr Hlineny (Masaryk Univ, Czech). 2011 Christian-Albrechts-University award 2011-2013, approx 400,000 Euro for the project, “Ef- ficient Polynomial Time Approximation Schemes for Scheduling and Related Optimization Prob- lems,” awarded to Klaus Jansen. 2011 Czech Republic 3-year Science Research Award to Petr Hlineny (Masaryk Univ, Czech) 2011 Christian-Albrechts-University award 2011-2013, approx 400,000 Euro for the project, “Ef- ficient Polynomial Time Approximation Schemes for Scheduling and Related Optimization Prob- lems”, awarded to Klaus Jansen. 2010 European Research Council Starting Grant of 1.4M Euros, beginning January 2010 for the project “The Parameterized Complexity of Reasoning Problems” awarded to Stefan Szeider, Vienna Univ of Technology. 2010 European Research Council Starting Grant of 2.2 million Euro for the project “Rigorous Theory of Preprocessing,” received by Fedor Fomin, University of Bergen. 2010 President of Ireland Young Researcher Award (PIYRA). The Award includes a massive grant of 700K Euros for 4 years. Igor’s project, “Parameterized Complexity of Multiway Cut,” succeeded against a prestigious interdisciplinary competition that included researchers from Bi- ology and Medical Sciences. Awarded to Igor Razgon, University of Cork. 2010 Australian Professorial Award, five year research-only academic position to Mike Fellows (Charles Darwin University). 2010 Bergen Research Foundation award of 12.5 million NOK over 4 years including a tenure- track position at the University of Bergen was awarded to Daniel Lokshtanov. Daniel has also received a 2-year Simons Foundation Postdoc at UCSD, San Diego, CA. 2010 Research Council of Norway award for her project: “SCOPE - Exploiting Structure to Cope with Hard Problems,” 2010-2014, approx 12M Nokia awarded to Pinar Heggernes, Bergen. 2010 Microsoft Research Travel Grant 2010-2015 to Saket Saraubh, MSRI, Chennai. 2010 NSERC grant renewed as of April 2010; 15K/year for 5 years for the project, “Parame- terized complexity analysis in cognitive science,” awarded to Todd Wareham. (Memorial Univ, Newfoundland, 2010 Humboldt Fellowship for Experienced Researchers. Daniel Marx will be in Berlin for 18 months, following a postdoc in Tel Aviv. 2010 Philips Prize of the Royal Mathematical Society in the Netherlands, for the best PhD research project. Award given to Matthias Mnich, whose Advisor was Gerhard Weoginger, Dept. Mathematics and Computer Science Eindhoven Univ of Technology. Mattias received a postdoc with Richard Karp, Berkeley, funded through a DAAD Fellowship. 2009 Agence Nationale de la Recherche, Programme Blanc Grant for the AGAPE Project, “Re- search in Fixed-Parameter and Exact Algorithmics”. The budget is approx 700k Euros for a period of 4 years. Project Leader Fred Havet (Nice), and Local Leaders D.Kratsch (Metz), I. Todinca (Orleans), and S. Thomasse and C. Paul (Montpellier). 2009 NSF CAREER award for her project titled, “CAREER: A Complete System for Protein Identification with Computational Approaches” The project uses parameterized complexity and tree decomposition. Awarded to Chunmei Liu, Howard University, Washington, DC.

Research team leaders active in Parameterized Complexity

Africa New Brunswick. Patricia Evans (Computa- Univ. of Johannesburg, South Africa. Anders tional Biology) Yeo University of Victoria, BC. Sue Whitesides Tanzania. Egbert Mujuni (Geometry), Ulrike Stege Australia Waterloo. Naomi Nishimura, Prabhakar Ragde Charles Darwin Univ. Michael Fellows (Algo- Czech Republic rithms, Generalist), Frances Rosamond (Social Masaryk University. Petr Hlineny Choice, Algorithms), Peter Shaw (Algorithms, Charles University, Prague. Daniel Kral Software Engineering) Chile Univ. Newcastle. Pablo Moscato (Comp Bio) Universidad de Chile. Juan Andres Montoya Griffith Univ. Vladimir Estivill-Castro (Algo- China rithms, Game Theory) Central South Univ., Changsha. Jianxin Wang, University of New South Wales. Toby Walsh Zhibiao Yang (Artificial Intelligence) Shanghai Jiaotong Univ., Shanghai. Yijia Chen Austria City Univ. of Hong Kong. Leizhen Cai Vienna Univ of Technology. Stefan Szeider, Denmark Reinhard Pichler (AI, SAT) Copenhagen. Thore Husfeldt Brazil Finland Federal University of Rio de Janeiro. Jayme Helsinki. Mikko Koivisto Szwarcfiter (Graphs) France Canada CIRM Luminy. Christophe Paul Carleton. Frank Dehne (Parallel Algorithms) LAMSADE and Univ. Dauphine. Vangelis Dalhousie University. Norbert Zeh Paschos, Cristina Bazgan McGill Univ. Michael Hallett (Biology) Lyon. Stephane Thomasse Memorial Univ. of Newfoundland. Todd Ware- Metz. Dieter Kratsch ham (Computational Biology, Brain Science) Germany RWTH Aachen. Peter Rossmanith, Arie Koster Nijmegen. Iris van Rooij Humboldt-Universität zu Berlin. Martin Grohe New Zealand Technische Universität Berlin. Stefan Auckland. Arkady Slinko Kreutzer, Rolf Niedermeier Massey. Catherine McCartin Dusseldorf. Jorg Rothe, Felix Brandt Wellington. Rodney Downey Freiburg. Jorg Flum Norway Karlsruhe. Detlef Seese Bergen. Fedor Fomin, Pinar Heggernes, Jan Christian Albrechts Univ., Keil. Klaus Jansen Arne Telle Luebeck. Rudiger Reischuk Poland Max Planck Research Institute, Saarbrucken. Univ. Warsaw. Marek Cygan Kurt Mehlhorn South Korea Univ. Saarlands, Saarbrucken. Jiong Guo Sangil Oum Trier. Henning Fernau Sweden Greece Lund. Thore Husfeldt Athens. Dimitrios M. Thilikos Peter Damaschke Hungary UK Budapest. Daniel Marx Oxford. Georg Gottlob India Durham. Paul Bonsma, Danial Paulusma Institute for Mathematical Sciences, Chennai. Leicester. Igor Razgon Venkatesh Raman, Saket Saurabh Royal Holloway. Gregory Gutin Ireland United States Cork. Barry O’Sullivan Buffalo. Kenneth W. Regan Israel Central Florida. Ron Dutton Haifa Technion. Hadas Shachnai (Approxima- Univ. of Chicago. Marcus Schafer tion) DePaul Univ. Iyad Kanj Tel Aviv. Noga Alon (Combinatorics), Benny Univ. Georgia. Liming Cai Chor, Ron Shamir (Computational Biology) Univ. of Maryland. MohammadTaghi Haji- Italy aghayi Marcus Cesati MIT. Erik D. Demaine Japan Univ. Ohio. David Juedes Tokyo. Ken-Ichi Kawarabayashi, Yusuke Univ Oregon. Andrzej Proskurowski Kobayashi, Osamu Watanabe Puerto Rico. Yiannis Koutis Lebanon Stanford. Ryan Williams Lebanese American Univ. Faisal Abu-Khasam Univ. Tennessee and Oak Ridge National Labs. Netherlands Michael Langston Utrecht. Hans Bodlaender Texas A&M. Jianer Chen Eindhoven. Gerhard Woeginger