Parameterized Complexity News

The Newsletter of the Parameterized Complexity Community Volume 4, April 2009

Welcome fpt.wikidot.com and mrfellows.net

Frances Rosamond, Editor Parameterized complexity has a WIKI!! The establish- Welcome to the latest issue of the Parameterized Com- ment of the wiki is largely due to Philip, student of plexity Newsletter. Our aim is to be provocative and Venkatesh Raman at IMSc, Chennai who searched for a informative, suggesting new problems while keeping the site that will accept LaTEX. We appreciate Philip for an community abreast of the rapidly expanding list of appli- outstanding job. A wiki is a community forum for sharing cations and techniques. The world records of FPT races news and ideas. It works just like wikipedia, although its (as we know them) are summarized. The newsletter pub- “skin” is a little diﬀerent (the appearance is changable). lishes exercises for classes, as well as new research ideas. Anyone can add or edit. Enjoy and please help keep it There have been an increasing number of parameter- up to date. ized complexity papers presented at conferences this past Philip has also helped create a website for Mike. He year. We are all proud of the smart researchers doing has written a program to ﬁll in the Bibtex and the lengthy such excellent work and I have tried to list some of them process of detailing all Mike’s papers is underway. But, in this newsletter. I apologize for those missed. Some it is quite a job. Mike has over 2000 citations (that non-parameterized papers have also probably been listed. are not self-citations by himself or co-authors) and over Contributions or requests may be sent to my email ad- 1000 are in the past 4 years. The “mrfellows.net” stands dress: ([email protected]). Suggestions for a newslet- for “Michael Ralph”. Note that Mike’s email address is ter logo are welcome. The newsletter is archived at [email protected]. the IWPEC website, (http://www.scs.carleton.ca/ ~dehne/iwpec) and at the new FPT wiki. Some New Developments

Gold Ring Project By Saket Saurabh ([email protected]) Independent Odd Cycle Transversal: In the In- The FPT Newsletter invites all the subprograms in the dependent Odd Cycle Transversal problem, we are Computer Journal Special Issue and others, to list the given as input a graph G =(V,E) and a positive integer most important problems waiting to be solved. The k and the question is whether there exists a set I ⊆ V Newsletter and wiki is willing to be a Central Clear- of size at most k such that I is an independent set and ing House. A “special ceremony” at IWPEC will induct G[V \ I] is bipartite. The parameterized complexity of members into the Gadgeteers Club. this problem has been open for some years now. Marx, Sullivan and Razgon have settled this open problem in aﬃrmative by obtaining a ﬁxed parameter tractable algorithm for Independent Odd Cycle Transversal. In fact they present a method for reducing the treewidth

Contents of this issue: PC and Artificial Intelligence ...... 2 Welcome...... 1 SocialChoice...... 3 GoldRingProject...... 1 Established FPT Races...... 5 fpt.wikidot.com and mrfellows.net ...... 1 SpecialIssue...... 6 Some New Developments ...... 1 NewDissertations...... 6 SteinerTree:...... 2 Conferences...... 6 Kernelization for Dominating Set: ...... 2 Positions Advertised ...... 10 Kernelization Lower Bounds: ...... 2 Parameterized Complexity News 2 of a graph while preserving all the minimal s − t sep- Kernelization Lower Bounds: Many problems arators. This technique seems very useful in designing have been shown to admit polynomial kernels, but it parameterized algorithms for cut problems. The relevant is only recently that a framework for showing the non- literature can be found here. existence of polynomial kernels for specific problems has been developed by Bodlaender et al. [ICALP, 2008] and • Dániel Marx, Barry O’Sullivan and Igor Raz- Fortnow and Santhanam [STOC, 2008]. These two semi- gon, Treewidth reduction for constrained separation nal papers have led the foundation of kernelizationn lower and bipartization problems, CoRR abs/0902.3780 bounds. With few exceptions, all known kernelization (2009). lower bounds results have been obtained by directly ap- plying this framework. Recently, there has been a lot Steiner Tree: It is well known that Steiner Tree of progress in this direction. Bodlaender, Thomassé,and parameterized by the number of terminals can be solved Yeo introduced the notion of polynomial parameter trans- in time O(3knO(1)) using the famous Dreyfus-Wagner al- formations and combined this with non-trivial composi- gorithm. In a breakthrough result Koivisto et al.[STOC, tion algorithm and showed that the Disjoint Paths and 2007] obtained an algorithm running in time and space Disjoint Cycles problems do not admit a polynomial k O(1) 3 O(2 n ) using fast subset convolution. Continuing this kernel unless PH =Σp. In another result of this type, line of research Jesper gives an algorithm running in time Dom, Lokshtanov and Saurabh introduced a notion of col- O(2knO(1)) and using polynomial space. He introduced ors and ids and used it to show that Connected Vertex the concept of branching walks, and obtains the algo- Cover, Capacitated Vertex Cover, Steiner Tree, rithm by extending the inclusion exclusion algorithm of Unique Coverage and various other natural parame- Karp with branching walks. The article containing this terized problems do not admit a polynomial kernel unless 3 result can be found here. PH =Σp.

• Jesper Nederlof, Fast polynomial-space algorithms • Hans L. Bodlaender, St´ephanThomass´e,and An- using Mobius inversion: Improving on Steiner Tree ders Yeo, Analysis of Data Reduction: Transforma- and related problems, (2009). Available from home- tions give evidence for non-existence of polynomial page. kernels (2009).

Kernelization for Dominating Set: Dominating • Michael Dom, Daniel Lokshtanov, and Saket Set has been a test-bed for making subexponential time Saurabh: Incompressibility through Colors and IDs algorithms and linear kernelization on planar graphs. The (2009). seminal result of Alber et al. [JACM, 2004] obtaining a linear kernel for Dominating Set has been used as a template in obatining linear kernels for various prob- PC and Artificial Intelligence lems on planar graphs. This result was later extended to graphs of bounded genus by Fomin and Thilikos [ICALP, Probabilistic Analysis of Data Reduction and In- 2004]. Recently, Alon and Gutner extended this result tractable Parameterized Problems and obtained a kernel of size kc in graphs excluding a By Yong Gao ([email protected]), University of fixed graph H as a minor, where c only depends on |H|. British Columbia Okanagan, Canada. Data reduction is Alon and Gutner leave as an open problem whether one a key technique in designing efficient algorithms for fixed can obtain a polynomial kernel for Dominating Set in parameter tractable problem and exact exponential-time d-degenerate graphs. Philip, Raman, and Sikdar settled algorithms for NP-hard problems. In the artificial intelli- this open problem by obtaining a polynomial kernel in gence literature, pruning techniques based on simple and graphs excluding Ki,j as a subgraph. Observe that d- efficient-to-implement reduction rules also play a crucial degenerate graph does not have Kd+1,d+1 as a subgraph. role in the success of many industrial-strength solvers, most notably in satisfiability testing, constraint process- • Noga Alon and Shai Gutner, Kernels for the domi- ing, and heuristic state space search. nating set problem on graphs with an excluded mi- In artificial intelligence and theoretical computer sci- nor, ECCC Report TR08-066 ence, the continued interest over the past more than ten • Geevarghese Philip, Venkatesh Raman, and Som- nath Sikdar, Polynomial Kernels for Dominating Set in Ki,j -free and d-degenerate Graphs, (2009). Parameterized Complexity News 3 years in the phase transition phenomenon of random in- presently uses PageRank, but faster and better algo- stances of NP-complete problems is largely motivated by rithms are needed. Similar ranking algorithms may play the expectation that such study will help shed lights on a role in evaluating microarray datasets in bioinformatics, why simple heuristics work on typical problem instances determining how to combine gene expression information and in what situations. with network structure derived from gene ontologies or Yong Gao (University of British Columbia Okana- expression profile correlations. gan, Canada) has recently started an effort to extend Algorithms for merging preference aggregation are this line of research to intractable parameterized prob- needed in multi-agent intelligent systems such as com- lems. He is currently focusing on random instances of puterised air-traffic control where systems from neigh- the Weighted d-CNF Satisfiability problem (Weighted d- bouring countries may negotiate between themselves to SAT) generated under a variety of reasonable random track flights and recommend available runways, and in models. A recently-obtained result shows that an algo- Learning Theory where consensus by motion sensors may rithm based on data reduction techniques is able to solve help train robots to maintain balance. Arkadii Slinko a typical instance of Weighted d-SAT in fixed-parameter (U. Auckland) is investigating how to create autonomous time O(dknd) where n is the number of variables and k software agents capable of acting as group members and is the usual parameter in weighted SAT. This seems to participating in group decision making [10, 11]. be the first in the literature that provides a sound the- With funding by the German Research Agency, Detlef oretical evidence on the power of simple data reductions Seese (Uni Karlsruhe) is investigating trading strategies, for intractable parameterized problems and on the fixed- auctions (eBay.de), and intelligent systems in manage- parameter tractability of random instances of intractable ment of risk and complexity. All place high demands on parameterized problems. efficient protocols for consensus [7, 9]. 1. Y. Gao (2008). Data Reductions, Fixed Parameter Electronic voting requires new mechanisms for efficient, direct aggregation of preferences (referenda), and Tractability, and Random Weighted d-CNF Satisfi- new ballot technology. The possibility of voting sequen- ability. Submitted. tially on propositions involves proposition independence, 2. Y. Gao (2008). Phase Transitions and Complex- and possible sharing of information among voters. Some ity of Weighted Satisfiability and Other Intractable judges may be more expert and their votes given more Parameterized Problems, In Proceedings of the weight. The heart of consensus is a cooperative intent, 23rd AAAI Conference on Artificial Intelligence where members are willing to work together to find a so- (AAAI’08). lution that meets the need of the group. Society might 3. Y. Gao (2008). Random Instances of W[2]- wish to compensate members of society whose preferences Complete Problems: thresholds, complexity, and al- are far from the collective decision. We have shown that gorithms. In Proceedings of the 11th International lobbying in conditions of “direct democracy” is virtually Conference on Theory and Applications of Satisfia- impossible, even in conditions of complete information bility Testing (SAT’08). about voter preferences [4]. Lane Hemaspaandra (Univ. Rochester, NY) and Jörg Rothe (Dusseldorf) are part of a European Science Foun- PC and Social Choice dation EUROCORES “Modeling Intelligent Interaction: Computational Foundations of Social Choice” project of By [email protected]. Shared deci- over a million euros to help lay the computational founda- sion making arises everywhere in modern society: in pol- tions in this area. Hemaspaandra has an NSF National itics, economics, science and law. Large social networks Priorities grant for “Richer Understanding of the Com- supported by Web 2.0, electronic voting on videos, wikis, plexity of Election Systems.” blogs, speeches by politicians, new hires, committee mem- Computational Social Choice, with its own conference bers and essentially anything, and electronic support of series COMSOC, is shedding light on how all social an- business processes and services require algorithms for con- imals, from humans to bees and cockroaches, make col- sensus, judgment aggregation, ranking and negotiation. lective decisions. The Science and Technology section of A lengthy article in ACM SIGACT News (Jn 08) de- The Economist (Feb 14, 09) “Animal Behaviour: Deci- scribes some of the problems where consensus protocols sion, decisions,” describes how honeybees avoid group- are needed in distributed systems, algorithms and game think when coming to an agreement on a new nest site. theory at Google research labs. For example, Google A model by Christian List (London School of Economics) Parameterized Complexity News 4 and Larissa Conradt (U Sussex) shows that merely finding ing reduction by Rothe et al. a good nesting site is not enough, consensus comes from Classical research about consensus originated in Social scout bees sharing information and other bees checking it. Choice theory and has not usually taken computational In a study by JoséHalloy (Free U of Brussels), robotic complexity into account. For instance, while it may not cockroaches were integrated with real ones. By manipu- be possible to design a voting protocol that makes it im- lating the robots, which were in the minority, Halloy was possible for a voter to cheat in one way or another, it may able to persuade the cockroaches to choose an inappro- well be that cheating successfully turns out to be compu- priate shelter, even one that had been previously rejected tationally intractable, which may therefore be deemed an before being infiltrated by the fakes. acceptable risk. There are a multitude of important prob- Most problems about shared decision making are lems of Social Choice waiting to be addressed from the NP-complete or worse, but parameterized results by multivariate point of view. Rolf Niedermeier’s group (Jena) are encouraging. Ke- meny Score has been analyzed using as parameters the score itself, the maximum Kendall-Tau distance, aver- References age Kendall-Tau distance, number of candidates, number of voters, and maximum range of candidate positions. [1] N. Betzler, M. R. Fellows, J. Guo, R. Niedermeier, In each case, except for number of voters, exponential F. Rosamond. Fixed-parameter algorithms for Kemeny growth has been isolated to a function of the parameter, scores. In Proc. of 4th AAIM, LNCS 5034, 60–71, 2008. essentially making Kemeny Score a reasonable rule for small parameter values [1], [2]. [2] N. Betzler, M. Fellows, J. Guo, R. Niedermeier, F. Rosa- mond. Computing Kemeny Rankings, Parameterized by Dodgson (Lewis Carroll, “Alice in Wonderland”) de- the Average K-T Distance. In Proc. of 2nd COMSOC (U. veloped an editing rule that allows an Administrator to Endriss, P. Goldberg, Eds) Dept. CS, Univ. Liverpool, make the smallest possible number of swaps of neighbor- 85–96, 2008. ing candidates so that the resulting profile has a Con- dorcet Winner (wins in pairwise competition against ev- [3] Nadja Betzler, Jiong Guo, and Rolf Niedermeier. Parame- ery other candidate). Dodgson Score is FPT when terized computational complexity of Dodgson and Young parameterized by the number of candidates, and by the elections. In Proc 11th Scandinavian Workshop on Algo- score. Using dynamic programming, a Dodgson winner rithm Theory (SWAT’08), Vol 5124 LNCS 402-413, 2008. can be determined in time O(2k · nk + nm). This is FPT with the implication that Dodgson election is practical [4] R. Christian, M. Fellows, F. Rosamond, A. Slinko. On when the winner is close to being a Condorcet winner complexity of lobbying in multiple referenda. Review of (eg., k is small)[3]. We have investigated the generaliza- Economic Design, 11(3) 217-224, 2007. tion where each swap has a certain cost depending on [5] P. Faliszewski, E. Hemaspaandra, L. Hemaspaandra, J. the voter and the degraded alternative. An interpreta- Rothe. A richer understanding of the complexity of election could be the cost needed to collect signatures in a tion systems. In Fundamental Problems in Computing: petition, or the number of friends such occurrences of vot- Essays Honor Prof Daniel J. Rosenkrantz (S. Ravi, S. ers tend to persuade when they themselves change their Shukla, Eds) Springer, 2009. priorities. We have shown this cost generalization has a simply exponential kernel. [6] E. Hemaspaandra, L. Hemaspaandra, T. Tantau, In Young election systems the editing operation is O.Watanabe. On the Complexity of Kings. In Proc Intl to remove a minimum number of votes. Determining a Symp on Fundamentals of Computation Theory, LNCS Young winner is W[2]-complete when the parameter is ei- 4639, 328-340, 2007. To appear TCS. ther the number of deleted votes (Dual Young Score) or the number of remaining votes (Young Score)[3]. [7] M. Kress, S. Mostaghim, D. Seese. “Intelligent Business The W[2]-hardness proof for Dual Young Score is in Process Execution using Particle Swarm Optimization two parts: a parameterized reduction from the W[2]-hard and Binary Search Method”, accepted as chapter in book Red Blue Dominating Set to an intermediate prob- Nature Inspired Informatics for Intelligent Applications lem k/2-Red Blue Dominating Set, and then to Dual and Knowledge Discovery, 1 - 16, to appear 2009. Young Score Dual Young Score . The proof that [8] C. Lindner and J. Rothe. Fixed-Parameter Tractabil- Optimal is in W[2] is by a parameterized reduction to ity and Parameterized Complexity Applied to Prob- Lobbying and includes the use of a modified Set Pack- lems From Computational Social Choice. Supplement Parameterized Complexity News 5

In Mathematical Programming Glossary (A. Holder, 2. J. Chen, F. Fomin, Y. Liu, S. Lu and Y. Villanger. Ed)INFORMS Computing Society, Oct 2008. Improved Algorithms for the Feedback Vertex Set Problems. WADS 2007. [9] A. Mitschele, F. Schlottmann, D. Seese. Integrated Risk StéphanThomasséA quadratic kernel for feedback Management: Risk Aggregation and Allocation using In- vertex set. SODA 2009. telligent Systems. In Computational Methods in Finan- cial Engineering, Essays in Honour Manfred Gilli (G. J. 3. Fedor V. Fomin, Dimitrios M. Thilikos: Dominat- Konotghiorghes, B. Rustem, P. Winker, Eds) Springer ing Sets in Planar Graphs: Branch-Width and Ex- 317–342, 2008. ponential Speed-Up. SIAM J. Comput. 36(2): 281- 309 (2006) [10] A. Slinko. How the Size of a Coalition Affects its Chances Jianer Chen, Henning Fernau, Iyad A. Kanj and Ge to Influence an Election, Social Choice and Welfare, Xia: Parametric Duality and Kernelization: Lower 26(1)143-153 2006. Bounds and Upper Bounds on Kernel Size. SIAM J. Comput. 37(4): 1077-1106 (2007). [11] A. Slinko. Additive Representability of Finite Measure- ment Structures. In Mathematics of Preference, Choice, 4. V. Dujmovic, H. Fernau and M. Kaufmann. Fixed and Order: Essays in Honor Peter C. Fishburn (SJ Brams, parameter algorithms for one-sided crossing mini- WV Gehrlein, FS Roberts, Eds) Springer, 2009. mization revisited. GD 2003. 5. J. Kneis, A. Langer and P. Rosmanith. A New Algorithm for Finding Trees with Many Leaves, ISAAC 2008. 6. J. Daligault, G. Gutin, E. J. Kim and A. Yeo. FPT Established FPT Races algorithms and kernels for the directed k-leaf problem, Manuscript, 2008. The results gradually keep improving. The latest best results are summarized here. The table is not complete H.Fernau, F. V. Fomin, D. Lokshtanov, D. Raible, and we await information on your favorite problem. S. Saurabh and Y. Villanger: Kernel(s) for Prob- lems with No Kernel: On Out-Trees with Many Leaves, STACS 2009. Problem f(k) kernel Ref In this paper it has been showed that no poly(k)- k Vertex Cover 1.2738 2k 1 size kernel can exist unless the polynomial hierarchy FVS 5k k2 2 collapses to the third level, unless we are looking for √ a spanning tree with a given root. Planar DS 215.13 k 67k 3 7. Jianer Chen, Songjian Lu: Improved Algorithms for 1-Sided CM 1.4656k 4 Weighted and Unweighted Set Splitting Problems, Max Leaf O(4kk2 + poly(n)) 3.75k 5 COCOON 2007. Directed ML∗ O(3.72kpoly(n)) n-O(k3) 6 8. Y. Liu, S. Lu, J. Chen and S-H. Sze. Greedy Local- Set Splitting 2k 2k 7 ization and Color-Coding: Improved Matching and 3k Packing Algorithms. They also have a randomized 3-D Matching 2.77 8 result of 2.323k. IWPEC 2006. ∗ k O(1) k-Path 2 no k 9 9. R. Williams, Finding Paths of Length k in O∗(2k) Convex Recolour 4k O(k2) 10 Time, Inform. Process. Letters, 109(6):315–318, Clique Partition 2k 11 (2009). Cluster Editing 1.83k 4k 12 H. Bodlaender, R. Downey, M. Fellows and D. Her- melin, On Problems Without Polynomial Kernels, k O(1) Steiner Tree 2 no k 13 ICALP 2008. ∗ k 2 3-Hitting Set 2.076 O(k ) 14 Comment from Moritz Mueller: Pointed Path (the Min Fill-In O(k2nm +2.3597k) O(k2) 15 starting point of the length k path is given) has no strong subexponential kernelization, ’strong’ means that it doesn’t increase the parameter, unless ETH 1. J. Chen, I. Kanj and G. Xia. Improved Parameter- fails. k Path does not have polynomial kernel even ized Upper Bounds for Vertex Cover. MFCS 2006. Parameterized Complexity News 6

when restricted to planar and connected graphs. 2009. The first edition of the book can be down- An open problem is the subexponential kernelizabil- loaded free of charge (courtesy to Springer-Verlag) from ity for k-Path, and finding methods for excluding http://www.cs.rhul.ac.uk/ gutin/. subexponential kernelizations. 10. O. Ponta, F. Hüffnerand R. Niedermeier. Speed- ing up Dynamic Programming for Some NP-hard Graph Recoloring Problems. TAMC 2008. New Dissertations H. Bodlaender, M. Fellows, M. Langston, M. Ra- gan, F. Rosamond and M. Weyer.Kernelization for Congratulations, Doctor. Convex Recoloring. ACiD 2006. 11. E. Mujuni and F. Rosamond. Parameterized Com- Daniel Lokshtanov. New Methods in Parameterized plexity of the Clique Partition Problem. CATS Algorithms and Complexity. University of Bergen, Advi- 2008. sor Pinar Heggernes. 12. S. Böcker, S. Briesemeister, Q. Bui and Anke Truß. Moritz Müller. Parameterized Randomization. Albert- PEACE: Parameterized and Exact Algorithms for Ludwigs-Universitt Freiburg. Advisor JörgFlum. Cluster Editing. Manuscript, Lehrstuhl fürBioin- Jakub Szymanik. Quantifiers in TIME and SPACE: formatik, Friedrich-Schiller-UniversitätJena, 2007 Computational Complexity of Generalized Quantifiers in J. Guo. A More Effective Linear Kernelization for Natural Language. Institute for Logic, Language and Cluster Editing. ESCAPE 2007. Computation. Institute van Amsterdam. 13. A. Björklund, T. Husfeldt, P. Kaski and M. Koivisto. Fourier meets Möbius:Fast Subset Con- volution. STOC 2007. Conferences J. Nederlof, Fast polynomial-space algorithms using Mobius inversion: Improving on Steiner Tree These are some of the upcoming TCS related con- and related problems, (2009). ferences for 2009. Appreciation goes to Tom 14. M. Wahlström. Algorithms, Measures and Upper and his website for some of this information. Bounds for Satisfiability and Related Problems.¨ (http://www.dur.ac.uk/tom.friedetzky/conf.html). In- PhD Thesis, Department of Computer and Informa- cluded are parameterized papers that I recognized, and tion Science, Linköpingsuniversitet, Sweden, 2007. some of the non-parameterized work that people in the F. Abu-Khzam. Kernelization Algorithms for d- parameterized community are doing. hitting Set Problems. WADS 2007. It has been learnt that A. Soleimanfallah and A. December 13 – 7. Parameterized Complexity Yeo has obtained first time O∗((2 − )k), a con- and Approximation Algorithms. Dagstuhl Seminar stant, algorithm for 3-Hitting set problem and the 09511. Organizers: Erik Demaine, Mohammad Taghi Ha- feedback vertex set problem in tournaments. jiAghayi, and DánielMarx. 15. H. L. Bodlaender, P. Heggernes and Y. Villanger: December 16 – 18. ISAAC: International Sym- Faster Parameterized Algorithms for Minimum Fill- posium on Algorithms and Computation. Hawaii, In, ISAAC 2008. USA. Submission deadline: July 15, 2009. December 15 – 17. FSTTCS: Foundations of Soft- ware Technology and Theoretical Computer Sci- ence. IIT Kanpur, India. Submission Deadline : 7 July, 2009. Special Issue and a New Book October 15 – 17, 2009. GROW: 4th workshop on Graph Classes, Optimization, and Width Pa- Journal of Combinatorial Optimization, Special Issue on rameters. Bergen, Norway. This is a continuation of Parameterized Complexity. Call for papers. Editors: the series of meetings: Barcelona 2001, Prague 2005, and Mike Fellows, Fedor Fomin and Gregory Gutin. Eugene 2007, very successful events each resulting in a The second edition of “Digraphs” by J. Bang- special issue of Discrete Applied Mathematics. Jensen and Gregory Gutin was published in January Parameterized Complexity News 7

October 24 - 27. FOCS: Symposium on Foun- and Chalmers University of Technology and Goteborg dations of Computer Science. Submission deadline: University, Devdatt Dubhashi. April 2, 2009 Atlanta, GA, USA. Call for Participation. St.Petersburg, Russia, August October 3 - 5. ALT: Conference on Algorithmic 12-16, 2009. http://logic.pdmi.ras.ru/ssct09/. Students, Learning Theory. Porto, Portugal. Submission dead- send a brief letter of reference from advisor, to Alexander line: May 10, 2009. Kulikov, kulikov at logic.pdmi.ras.ru. COURSES by Lance Fortnow (Northwestern University, September 7 - 9. IWPEC: International Work- Toyota Technological Institute): Structural Complexity; shop on Parameterized and Exact Computation Nicola Galesi (Roma University): Proof Complexity; Uri part of ALGO. Copenhagen, Denmark. More info: Zwick (Tel Aviv University): Complexity of Graph Algo- http://algo2009.itu.dk/4th-IWPEC/ ESA 2009 (Euro- rithms Based on Matrix Multiplication. pean Symposium on Algorithms). Submission deadline: April 12, 2009. July 21 – 24. FSMNLP: 8th Intl Workshop Finite- State Methods and Natural Language Processing. September 2 - 4. FCT: Symposium on Fundamen- Uni Pretoria, South Africa. Submission Deadline: 13 tals of Computation Theory. Submission deadline: April. The CFP explicitly mentions FPT. Merged with April 9, 2009. Wroclaw, Poland. FASTAR (Finite Automata Systems Theoretical and Ap- August 24 - 28. MFCS: Symposium on Mathe- plied Research). Note: A number of related events take matical Foundations of Computer Science. Novy place in the southern hemisphere in the weeks before and Smokovec, High Tatras, Slovakia. Submission deadline: after FSMNLP 2009: The first African edition of the April 10, 2009. String Masters workshop (ASM 2009) will be held at Stel- August 21 - 23. APPROX: Workshop on Approx- lenbosch, South Africa on July 27 - 31. imation Algorithms for Combinatorial Optimiza- The first Australian edition of the String Masters work- tion Problems. UC Berkeley, USA. Submission dead- shop (Aussie StringMasters 2009) will be held in Perth, line: April 12, 2009. Co-located with RANDOM 2009. Australia on August 3 - 7. August 21 - 29. WADS: Algorithms and Data The joint conference of the ACL and AFNLP (ACL- Structures Symposium. Banff, Alberta. IJCNLP 2009) will be held in Singapore on August 2 - 7. The Conference on Implementation and Application of August 18 - 23. CSR: 4th International Com- Automata (CIAA 2009) will be held in Sydney, Australia puter Science Symposium in Russia. Novosibirsk, on July 14th - 17th. Russia. Stefan Richter, Daniel Moelle, Peter Rossmanith and Dogan Kesdogan. Breaking Anonymity by Learning July 19 - 24. CiE: Mathematical Theory and Com- a Unique Minimum Hitting Set. putational Practice. Heidelberg, Germany. Y. Chen, Somnath Sikdar, Neeldhara Misra, Saket Saurabh and J. Flum, Moritz Müller.Lower bounds for kernelizations Venkatesh Raman. The Budgeted Unique Coverage Prob- and other preprocessing procedures. lem and Color-Coding. Barnaby Martin and Stefan Dantchev. Cutting planes and the parameter cutwidth. NoNA- Nordic Network on Algorithms. August 12-16, 09 NoNA Summer School on Com- June 30 – July 3. SAT: Twelfth International plexity Theory, St. Petersburg, Russia University of Conference on Theory and Applications of Sat- Bergen. isfiability Testing. Swansea, Wales, United Kingdom. March 12 - 15, 09 NoNA Spring School on Algo- Stefan Szeider, Program Committee. rithms, Istanbul, Turkey. June 20 - 23. FAW: 3rd International Frontiers of Activities of NoNA are coordinated by University of Algorithmics Workshop. Hefei, China. Bergen Department of Informatics, Fedor V. Fomin and Stefan Richter, Daniel Moelle, Peter Rossmanith and Pinar Heggernes; Lund University, Andrzej Lingas; Uni- Dogan Kesdogan. Breaking Anonymity by Learning a versity of Aarhus, Gerth S. Brodal; Linkping Univer- Unique Minimum Hitting Set. sity, Peter Jonsson; IT University of Copenhagen, Anna Somnath Sikdar, Neeldhara Misra, Saket Saurabh and stlin Pagh; University of Iceland, Magns M. Halldrsson; Venkatesh Raman. The Budgeted Unique Coverage Prob- University of Helsinki, Esko Ukkonen; KTH Stockholm, lem and Color-Coding. Johan Hstad; University of Southern Denmark, Jrgen June 28 - July 2. IWOCA. Hradec nad Moravici, Bang-Jensen; Vilnius University, Algimantas Juozapavi- Czech Republic. Mike Fellows invited speaker. cius; University of Latvia, Rusins Freivalds; Steklov Insti- June 24 - 26. WG: 35th International Workshop tute of Mathematics at St.Petersburg, Edward A. Hirsch; Parameterized Complexity News 8 on Graph-Theoretic Concepts in Computer Sci- tonomous Agents and Multiagent. Budapest. Nadja ence. Montpellier, France. Rolf Niedermeier program Betzler, Michael Fellows, Jiong Guo, Rolf Niedermeier, committee member. Frances Rosamond. How Similarity Helps to Efficiently June. AAIM: Algorithmic Aspects in Informa- Compute Kemeny Rankings. tion and Management. San Francisco. Jiong Guo, May 18 - 22. TAMC: 6th Annual Conference on Christian Komusiewicz, Rolf Niedermeier, and Johannes Theory and Applications of Models of Computa- Uhlmann. A More Relaxed Model for Graph-Based Data tion. Special Invited Session on Algorithms and Com- Clustering: s-Plex Editing. plexity Organizing Chair: Iyad A. Kanj, DePaul Univ., June. SEA: 8th International Symposium on Ex- USA, Jiong Guo, Jena, Invited Speaker. perimental Algorithms. Dortmund. Hannes Moser, Jianer Chen, Iyad Kanj and Ge Xia. On Parameterized Rolf Niedermeier, Manuel Sorge. Algorithms and Ex- Exponential Time Complexity. periments for Clique Relaxations - Finding Maximum s- Pinar Heggernes, Daniel Meister and Charis Papadopou- Plexes. los. A complete characterisation of the linear clique-width of path powers. June. 20th Annual Symposium on Combinato- Daniel Lokshtanov, Matthias Mnich and Saket Saurabh. rial Pattern Matching. Lille, France. Christian Ko- Linear Kernel for Planar Connected Dominating Set. musiewicz, Rolf Niedermeier, and Johannes Uhlmann. Jiri Fiala, Petr Golovach and Jan Kratochvil. Parameter- Deconstructing Intractability A Case Study for Interval ized Complexity of Coloring Problems: Treewidth versus Constrained Coloring. Vertex Cover. May 25 - 29. Corsica Spring School Jianxin Wang and Guohong Jiang. A Fixed-parameter on Fixed Parameter and Exact Algo- Enumeration Algorithm for Weighted FVS Problem. rithms. Ile Rousse, Corsica (France. http://www- Faisal Abu-Khzam. Quadratic Kernel for 3-Set Packing. sop.inria.fr/mascotte/seminaires/AGAPE/. Email Fred- April 19 - 24. Adaptive, Output Sensitive, Online [email protected]. Fixed parameter tractable and Parameterized Algorithms. Dagstuhl Seminar (FPT) and exponential-time algorithms are hot topics 09171. Organizers: Jeremy Barbay (University of San- in algorithms. Both approaches aim at reducing the tiago), Rolf Klein (Universitt Bonn), Alejandro Lopez- combinatorial explosion of NP-hard problems. In moder- Ortiz (University of Waterloo), Rolf Niedermeier (Uni- ately exponential-time algorithms, we search for fastest versitt Jena). possible exact algorithms typically the exponential time depends on the size of the instance which should be prac- March 23 - 25. DIMAP workshop on ”Al- tical on instances of moderate sizes. In FPT, the idea is gorithmic Graph Theory. The newly established to design algorithms for which the exponential factor of Centre for Discrete Mathematics and its applications the running-time only depends on some parameter which (DIMAP) at the University of Warwick is organising a is expected to be small in practical use. series on workshops on different emerging research topics. http://www2.warwick.ac.uk/fac/cross fac/dimap/ The school adresses doctoral and post-doctoral stu- events/agt2009. Keynote Speakers: Rolf Nieder- dents as well as confirmed researchers working in or in- meier, Friedrich-Schiller-Universitt Jena; Bruno Cour- terested by these areas. Two to three hours lectures, dis- celle, Laboratoire Bordelais de Recherche en Informa- cussions on each of the topics, open problems sessions. tique (LaBRI), Bordeaux; Martin Golumbic, University Lectures: of Haifa. M. Fellows: Introduction to fixed parameter tractability Daniel Brgmann, Christian Komusiewicz, and Hannes and overview of the field Moser. On Generating Triangle-Free Graphs. T. Husfeldt, P. Kaski: Introduction to exact exponential algorithms March. Israel Theory Day. Word is that 7–8 of the D. Marx: FPT algorithmic techniques top Israeli TCS gave 1 hour talks about their current F. Grandoni: Analysis of exact algorithms research, and that Noga Alon dedicated his talk to pa- S. Saurabh and D. Lokshtanov: Kernels - lower and up- rameterized algorithmics. per bounds February. STACS. Nicolas Bousquet, Jean Daligault, M. Fellows: FPT complexity and W- hierarchy StéphanThomasséand Anders Yeo. A Polynomial Ker- D. Kratsch: Branching algorithms nel for Multicut In Trees. F. Fomin: Subexponential algorithms, bidimensonality. Andrei A. Bulatov, Victor Dalmau, Martin Grohe, and May. AAMAS: International Conference on Au- DánielMarx. Enumerating Homomorphisms. Erik D. Demaine, MohammadTaghi Hajiaghayi, Hamid Parameterized Complexity News 9

Mahini and Morteza Zadimoghaddam. The Price of An- Klembt, Vadim Lozin and Raffaele Mosca. Independent archy in Cooperative Network Creation Games. Sets of Maximum Weight in Apple-Free Graphs. Fedor Fomin, Petr Golovach and Dimitrios Thilikos. Jaroslaw Byrka, Sylvain Guillemot and Jesper Jansson. Approximating Acyclicity Parameters of Sparse Hyper- New Results on Optimizing Rooted Triplets Consistency. graphs. Hee-Kap Ahn, Peter Brass, Christian Knauer, Hyeon-Suk Michael R. Fellows, Jiong Guo, Hannes Moser and Rolf Na and Chan-Su Shin. Covering a Simple Polygon by Niedermeier. A Generalization of Nemhauser and Trot- Monotone Directions. ter’s Local Optimization Theorem. Hans L. Bodlaender, Pinar Heggernes and Yngve Vil- Henning Fernau, Fedor V. Fomin, Daniel Lokshtanov, langer. Faster parameterized algorithms for Minimum Daniel Raible, Saket Saurabh and Yngve Villanger. Ker- Fill-In. nel(s) for Problems with No Kernel: On Out-Trees with Somnath Sikdar, Venkatesh Raman, Saket Saurabh and Many Leaves. Leslie Ann Goldberg, Martin Grohe, Mark Sounaka Mishra. Konig Deletion Sets and Vertex Covers Jerrum and Marc Thurley. A Complexity Dichotomy for Above the Matching Size. Partition Functions with Mixed Signs. Christian Knauer and Marc Scherfenberg. Approximate Danny Hermelin, Gad M. Landau, Shir Landau and nearest neighbor search under translation invariant Haus- Oren Weimann. A Unified Algorithm for Accelerating dorff distance. Edit-Distance Computation via Text-Compression. Elias Vicari, Matus Mihalak, Peter Widmayer, Alex Hall, Juraj Hromkovic and Georg Schnitger. Ambiguity and Fedor Fomin and Petr Golovach. How to Guard a Graph?. Communication. Eelko Penninkx and Hans L. Bodlaender. A Linear Ker- Stefan Kratsch. Polynomial Kernelizations for nel for the k-Disjoint Cycle Problem on Planar Graphs. + MIN F Π1 and MAX NP. Daniel Raible and Henning Fernau. Power Domination DánielMarx. Tractable Structures for Constraint Satis- in O∗(1.7548n) using Reference Search Trees. faction with Truth Tables. Joachim Kneis, Alexander Langer and Peter Rossmanith. February. WALCOM. Michael Dom, Michael Fellows A New Algorithm for Finding Trees with Many Leaves. and Frances A. Rosamond. Parameterized Complexity of Michael Lampis, Georgia Kaouri, Valia Mitsou. On the Stabbing Rectangles and Squares in the Plane, 298–309. Algorithmic Effectiveness of Digraph Decompositions and Complexity Measures. January. SOFSEM: 35th International Confer- Michael Fellows, Daniel Lokshtanov, Neeldhara Misra, ence on Current Trends in Theory and Practice Frances A. Rosamond and Saket Saurabh. Graph Lay- of Computer Science. Hannes Moser. A Problem Ker- out problems Parameterized by Vertex Cover. nelization for Graph Packing. Michael Fellows, Daniel Meister, Frances A. Rosamond, January. SODA. Erik D. Demaine, Dion Harmon, John R. Sritharan and Jan Arne Telle. Leaf Powers and Their Iacono, Daniel Kane and Mihai Patrascu. The Geometry Properties: Using the Trees. of Binary Search Trees. Leizhen Cai, Elad Verbin and Lin Yang. Firefight- Fedor V. Fomin, Petr A. Golovach, Daniel Lokshtanov, ing on Trees: (1-1/e)–Approximation, Fixed Parameter and Saket Saurabh. Clique-Width: On the Price of Gen- Tractability and a New Subexponential Algorithm. erality. November 2008. ICYCS: 9th International Con- Serge Gaspers and Gregory Sorkin. A universally fastest ference for Young Computer Scientists. Zhangjia- algorithm for Max 2-Sat, Max 2-CSP, and everything in jie, China. Mike Fellows and Mike Langston were invited between. keynote speakers. Mike Fellows and Fran Rosamond also Klaus Jansen. Parameterized approximation scheme for spoke at Central South University, Changsha, where they the multiple knapsack problem met with the research group of Prof Jianxin Wang. Ken-ichi Kawarabayashi, Erik Demaine and Mohammad Taghi Haijaghayi. Additive Approximation Algorithms Aug 24 – Sept 6, 2008. Taiwan. Rolf Niedermeier for List-Coloring Minor-Closed Class of Graphs. and Peter Rosmanith gave a week-long workshop on Pa- Ken-ichi Kawarabayashi and Bojan Mohar. List-Color- rameterized Complexity in Taiwan, giving talks at Na- Critical Graphs on a Fixed Surface. tional Chung Cheng University, National Tsing Hua Uni- Dániel Marx. Approximating Fractional Hypertree versity, National Dong Hwa University, and Academia Width. Sinica, Taipei. StéphanThomassé.A quadratic kernel for feedback vertex set. December 2008. ISAAC. Andreas Brandstadt, Tilo Parameterized Complexity News 10

Figure 1: Rolf Niedermeier, Daniel Lokshtanov, Danny Hermelin, and Yonatan Aumann at IWPEC 2008.

Positions Advertised university-wide projects as well as to successfully apply for external research funding. Royal Holloway, UK LECTURESHIP IN MATHS; Teaching duties associated with the position will focus Discrete Maths is one of the areas we’re most on lectures for advanced students in the area of algorithm interested in (see the link below). Department engineering. Leadership in the development of an Algo- of Mathematics Royal Holloway, University of Lon- rithm Engineering Laboratory is also expected. don, Egham, Surrey TW20 0EX, United King- The review of applications for the position has started. dom. http://www.rhul.ac.uk/Personnel/Ads/X0309- 0586.html. Contact Prof. Gregory Gutin.

Univ Karlsruhe, Germany ASSOC PROF IN COM- Appointments and Positions PUTER SCIENCE. Contact Detlef Seese. D´anielMarx has accepted a one-year position with Noga Institute of Informatics, Friedrich-Schiller- Alon in Israel. University Jena, Germany ASSISTANT PROFES- Henning Fernau is visiting the University of Newcastle, SOR (W1) for Algorithm Engineering. The position is Australia for several months beginning March. supported by the Carl Zeiss Foundation. A successful Jan Kratochvil will visit the University of Newcastle, Aus- candidate will become part of the Jena research focus tralia in April. on data-driven algorithmics. Our group has a strong interest in research concerning algorithms for NP-hard problems (particularly, but not exclusively, parameterized algorithmics). Activities in cooperation with the Congratulations! Jena research teams could target applications in such areas as computational biology, computational geome- Jianer Chen, Associate Editor, IEEE Transactions on try, algorithmic graph theory, or computational social Computers, 2009. choice. A successful candidate is expected to take part in Michael Fellows, Associate Editor, ACM Transactions on Algorithms, 2009.