TY - CONF AU - Jacob, Riko AU - Ritscher, Stephan AU - Scheideler, Christian AU - Schmid, Stefan ID - 1930 T2 - Algorithms and Computation, 20th International Symposium, ISAAC 2009, Honolulu, Hawaii, USA, December 16-18, 2009. Proceedings TI - A Self-stabilizing and Local Delaunay Graph Construction VL - 5878 ER - TY - CONF AU - Jacob, Riko AU - W. Richa, Andrea AU - Scheideler, Christian AU - Schmid, Stefan AU - Täubig, Hanjo ID - 1932 SN - 978-1-60558-396-9 T2 - Proceedings of the 28th Annual ACM Symposium on Principles of Distributed Computing, PODC 2009, Calgary, Alberta, Canada, August 10-12, 2009 TI - A distributed polylogarithmic time algorithm for self-stabilizing skip graphs ER - TY - CONF AU - Baumgart, Matthias AU - Scheideler, Christian AU - Schmid, Stefan ID - 1933 SN - 978-1-60558-606-9 T2 - SPAA 2009: Proceedings of the 21st Annual ACM Symposium on Parallelism in Algorithms and Architectures, Calgary, Alberta, Canada, August 11-13, 2009 TI - A DoS-resilient information system for dynamic data management ER - TY - CONF AU - Gall, Dominik AU - Jacob, Riko AU - W. Richa, Andrea AU - Scheideler, Christian AU - Schmid, Stefan AU - Täubig, Hanjo ID - 1934 SN - 978-3-642-05117-3 T2 - Stabilization, Safety, and Security of Distributed Systems, 11th International Symposium, SSS 2009, Lyon, France, November 3-6, 2009. Proceedings TI - Brief Announcement: On the Time Complexity of Distributed Topological Self-stabilization VL - 5873 ER - TY - CONF AU - Doerr, Benjamin AU - Ann Goldberg, Leslie AU - Minder, Lorenz AU - Sauerwald, Thomas AU - Scheideler, Christian ID - 1935 T2 - Algorithmic Methods for Distributed Cooperative Systems, 06.09. - 11.09.2009 TI - Stabilizing Consensus with the Power of Two Choices VL - 09371 ER - TY - JOUR AU - Meyer auf der Heide, Friedhelm AU - Scheideler, Christian ID - 1903 IS - 5 JF - Informatik Spektrum TI - Algorithmische Grundlagen verteilter Speichersysteme ER - TY - JOUR AU - Gavoille, Cyril AU - Patt-Shamir, Boaz AU - Scheideler, Christian ID - 1904 IS - 4 JF - Theory of Computing Systems TI - Foreword ER - TY - CONF AU - Gall, Dominik AU - Jacob, Riko AU - W. Richa, Andrea AU - Scheideler, Christian AU - Schmid, Stefan AU - Täubig, Hanjo ID - 1905 SN - 978-3-642-12199-9 T2 - LATIN 2010: Theoretical Informatics, 9th Latin American Symposium, Oaxaca, Mexico, April 19-23, 2010. Proceedings TI - Time Complexity of Distributed Topological Self-stabilization: The Case of Graph Linearization VL - 6034 ER - TY - CONF AU - Richa, Andrea W. AU - Zhang, Jin AU - Scheideler, Christian AU - Schmid, Stefan ID - 1906 SN - 978-1-60558-888-9 T2 - Proceedings of the 29th Annual ACM Symposium on Principles of Distributed Computing, PODC 2010, Zurich, Switzerland, July 25-28, 2010 TI - Brief announcement: towards robust medium access in multi-hop networks ER - TY - CONF AU - Richa, Andrea W. AU - Scheideler, Christian AU - Schmid, Stefan AU - Zhang, Jin ID - 1907 SN - 978-3-642-15762-2 T2 - Distributed Computing, 24th International Symposium, DISC 2010, Cambridge, MA, USA, September 13-15, 2010. Proceedings TI - A Jamming-Resistant MAC Protocol for Multi-Hop Wireless Networks VL - 6343 ER - TY - CONF AU - Doerr, Benjamin AU - Ann Goldberg, Leslie AU - Minder, Lorenz AU - Sauerwald, Thomas AU - Scheideler, Christian ID - 1908 T2 - Distributed Computing, 24th International Symposium, DISC 2010, Cambridge, MA, USA, September 13-15, 2010. Proceedings TI - Brief Announcement: Stabilizing Consensus with the Power of Two Choices VL - 6343 ER - TY - CONF AU - W. Richa, Andrea AU - Scheideler, Christian AU - Schmid, Stefan AU - Zhang, Jin ID - 1891 SN - 978-0-7695-4364-2 T2 - 2011 International Conference on Distributed Computing Systems, ICDCS 2011, Minneapolis, Minnesota, USA, June 20-24, 2011 TI - Competitive and Fair Medium Access Despite Reactive Jamming ER - TY - CONF AU - W. Richa, Andrea AU - Scheideler, Christian AU - Schmid, Stefan AU - Zhang, Jin ID - 1892 SN - 978-1-4503-0868-7 T2 - Proceedings of the 3rd ACM workshop on Wireless of the students, by the students, for the students, S3@MOBICOM 2011, Las Vegas, NV, USA, September 19 - 23, 2011 TI - Towards jamming-resistant and competitive medium access in the SINR model ER - TY - CONF AU - W. Richa, Andrea AU - Scheideler, Christian AU - Schmid, Stefan AU - Zhang, Jin ID - 1893 SN - 978-1-4503-0722-2 T2 - Proceedings of the 12th ACM Interational Symposium on Mobile Ad Hoc Networking and Computing, MobiHoc 2011, Paris, France, May 16-20, 2011 TI - Self-stabilizing leader election for single-hop wireless networks despite jamming ER - TY - CONF AU - Kniesburges, Sebastian AU - Koutsopoulos, Andreas AU - Scheideler, Christian ID - 1895 SN - 978-1-4503-0743-7 T2 - SPAA 2011: Proceedings of the 23rd Annual ACM Symposium on Parallelism in Algorithms and Architectures, San Jose, CA, USA, June 4-6, 2011 (Co-located with FCRC 2011) TI - Re-Chord: a self-stabilizing chord overlay network ER - TY - CONF AU - Kniesburges, Sebastian AU - Scheideler, Christian ID - 1899 SN - 978-3-642-19093-3 T2 - WALCOM: Algorithms and Computation - 5th International Workshop, WALCOM 2011, New Delhi, India, February 18-20, 2011. Proceedings TI - Hashed Patricia Trie: Efficient Longest Prefix Matching in Peer-to-Peer Systems VL - 6552 ER - TY - CHAP AU - Scheideler, Christian AU - Graffi, Kalman ID - 1900 SN - 978-1-4614-1167-3 T2 - Computer Science, The Hardware, Software and Heart of It TI - Programming for Distributed Computing: From Physical to Logical Networks ER - TY - CHAP AU - Scheideler, Christian ID - 1901 SN - 978-3-642-15327-3 T2 - Algorithms Unplugged TI - Broadcasting - How Can I Quickly Disseminate Information? ER - TY - CONF AU - Kolman, Petr AU - Scheideler, Christian ID - 1924 T2 - 28th International Symposium on Theoretical Aspects of Computer Science, STACS 2011, March 10-12, 2011, Dortmund, Germany TI - Towards Duality of Multicommodity Multiroute Cuts and Flows: Multilevel Ball-Growing ER - TY - CONF AB - In the standard consensus problem there are n processes with possibly di®erent input values and the goal is to eventually reach a point at which all processes commit to exactly one of these values. We are studying a slight variant of the consensus problem called the stabilizing consensus problem [2]. In this problem, we do not require that each process commits to a ¯nal value at some point, but that eventually they arrive at a common, stable value without necessarily being aware of that. This should work irrespective of the states in which the processes are starting. Our main result is a simple randomized algorithm called median rule that, with high probability, just needs O(logmlog log n + log n) time and work per process to arrive at an almost stable consensus for any set of m legal values as long as an adversary can corrupt the states of at most p n processes at any time. Without adversarial involvement, just O(log n) time and work is needed for a stable consensus, with high probability. As a by-product, we obtain a simple distributed algorithm for approximating the median of n numbers in time O(logmlog log n + log n) under adversarial presence. AU - Doerr, Benjamin AU - Goldberg, Leslie Ann AU - Minder, Lorenz AU - Sauerwald, Thomas AU - Scheideler, Christian ID - 645 T2 - Proceedings of the 23rd ACM Symposium on Parallelism in Algorithms and Architectures (SPAA) TI - Stabilizing consensus with the power of two choices ER - TY - CONF AB - This paper presents a dynamic overlay network based on the De Bruijn graph which we call Linearized De Bruijn (LDB) network. The LDB network has the advantage that it has a guaranteed constant node degree and that the routing between any two nodes takes at most O(log n) hops with high probability. Also, we show that there is a simple local-control algorithm that can recover the LDB network from any network topology that is weakly connected. AU - Richa, Andrea W. AU - Scheideler, Christian ID - 646 T2 - Proceedings of the 13th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS) TI - Self-Stabilizing DeBruijn Networks ER - TY - CONF AB - We present Corona, a deterministic self-stabilizing algorithm for skip list construction in structured overlay networks. Corona operates in the low-atomicity message-passing asynchronous system model. Corona requires constant process memory space for its operation and, therefore, scales well. We prove the general necessary conditions limiting the initial states from which a self-stabilizing structured overlay network in message-passing system can be constructed. The conditions require that initial state information has to form a weakly connected graph and it should only contain identiers that are present in the system. We formally describe Corona and rigorously prove that it stabilizes from an arbitrary initial state subject to the necessary conditions. We extend Corona to construct a skip graph. AU - Nesterenko, Mikhail AU - Mohd, Rizal AU - Scheideler, Christian ID - 662 T2 - Proceedings of the 13th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS) TI - Corona: A Stabilizing Deterministic Message-Passing Skip List ER - TY - JOUR AU - Dolev, Shlomi AU - Scheideler, Christian ID - 1882 JF - Theor. Comput. Sci. TI - Editorial for Algorithmic Aspects of Wireless Sensor Networks ER - TY - CONF AU - Monien, Burkhard AU - Scheideler, Christian ID - 1884 SN - 978-3-642-32819-0 T2 - Euro-Par 2012 Parallel Processing - 18th International Conference, Euro-Par 2012, Rhodes Island, Greece, August 27-31, 2012. Proceedings TI - Selfish Distributed Optimization VL - 7484 ER - TY - JOUR AB - This article studies the construction of self-stabilizing topologies for distributed systems. While recent research has focused on chain topologies where nodes need to be linearized with respect to their identiers, we explore a natural and relevant 2-dimensional generalization. In particular, we present a local self-stabilizing algorithm DStab which is based on the concept of \local Delaunay graphs" and which forwards temporary edges in greedy fashion reminiscent of compass routing. DStab constructs a Delaunay graph from any initial connected topology and in a distributed manner in time O(n3) in the worst-case; if the initial network contains the Delaunay graph, the convergence time is only O(n) rounds. DStab also ensures that individual node joins and leaves aect a small part of the network only. Such self-stabilizing Delaunay networks have interesting applications and our construction gives insights into the necessary geometric reasoning that is required for higherdimensional linearization problems.Keywords: Distributed Algorithms, Topology Control, Social Networks AU - Jacob, Riko AU - Ritscher, Stephan AU - Scheideler, Christian AU - Schmid, Stefan ID - 570 JF - Theoretical Computer Science TI - Towards higher-dimensional topological self-stabilization: A distributed algorithm for Delaunay graphs ER - TY - JOUR AB - We present Tiara — a self-stabilizing peer-to-peer network maintenance algorithm. Tiara is truly deterministic which allows it to achieve exact performance bounds. Tiara allows logarithmic searches and topology updates. It is based on a novel sparse 0-1 skip list. We then describe its extension to a ringed structure and to a skip-graph.Key words: Peer-to-peer networks, overlay networks, self-stabilization. AU - Clouser, Thomas AU - Nesterenko, Mikhail AU - Scheideler, Christian ID - 574 JF - Theoretical Computer Science TI - Tiara: A self-stabilizing deterministic skip list and skip graph ER - TY - JOUR AB - A left-to-right maximum in a sequence of n numbers s_1, …, s_n is a number that is strictly larger than all preceding numbers. In this article we present a smoothed analysis of the number of left-to-right maxima in the presence of additive random noise. We show that for every sequence of n numbers s_i ∈ [0,1] that are perturbed by uniform noise from the interval [-ε,ε], the expected number of left-to-right maxima is Θ(&sqrt;n/ε + log n) for ε>1/n. For Gaussian noise with standard deviation σ we obtain a bound of O((log3/2 n)/σ + log n).We apply our results to the analysis of the smoothed height of binary search trees and the smoothed number of comparisons in the quicksort algorithm and prove bounds of Θ(&sqrt;n/ε + log n) and Θ(n/ε+1&sqrt;n/ε + n log n), respectively, for uniform random noise from the interval [-ε,ε]. Our results can also be applied to bound the smoothed number of points on a convex hull of points in the two-dimensional plane and to smoothed motion complexity, a concept we describe in this article. We bound how often one needs to update a data structure storing the smallest axis-aligned box enclosing a set of points moving in d-dimensional space. AU - Damerow, Valentina AU - Manthey, Bodo AU - Meyer auf der Heide, Friedhelm AU - Räcke, Harald AU - Scheideler, Christian AU - Sohler, Christian AU - Tantau, Till ID - 579 IS - 3 JF - Transactions on Algorithms TI - Smoothed analysis of left-to-right maxima with applications ER - TY - CONF AB - Nanoparticles are getting more and more in the focus of the scientic community since the potential for the development of very small particles interacting with each other and completing medical and other tasks is getting bigger year by year. In this work we introduce a distributed local algorithm for arranging a set of nanoparticles on the discrete plane into specic geometric shapes, for instance a rectangle. The concept of a particle we use can be seen as a simple mobile robot with the following restrictions: it can only view the state of robots it is physically connected to, is anonymous, has only a constant size memory, can only move by using other particles as an anchor point on which it pulls itself alongside, and it operates in Look-Compute-Move cycles. The main result of this work is the presentation of a random distributed local algorithm which transforms any given connected set of particles into a particular geometric shape. As an example we provide a version of this algorithm for forming a rectangle with an arbitrary predened aspect ratio. To the best of our knowledge this is the rst work that considers arrangement problems for these types of robots. AU - Drees, Maximilian AU - Hüllmann (married name: Eikel), Martina AU - Koutsopoulos, Andreas AU - Scheideler, Christian ID - 581 T2 - Proceedings of the 26th IEEE International Parallel and Distributed Processing Symposium (IPDPS) TI - Self-Organizing Particle Systems ER - TY - CONF AB - This paper initiates the formal study of a fundamental problem: How to efficiently allocate a shared communication medium among a set of K co-existing networks in the presence of arbitrary external interference? While most literature on medium access focuses on how to share a medium among nodes, these approaches are often either not directly applicable to co-existing networks as they would violate the independence requirement, or they yield a low throughput if applied to multiple networks. We present the randomized medium access (MAC) protocol COMAC which guarantees that a given communication channel is shared fairly among competing and independent networks, and that the available bandwidth is used efficiently. These performance guarantees hold in the presence of arbitrary external interference or even under adversarial jamming. Concretely, we show that the co-existing networks can use a Ω(ε2 min{ε, 1/poly(K)})-fraction of the non-jammed time steps for successful message transmissions, where ε is the (arbitrarily distributed) fraction of time which is not jammed. AU - Richa, Andrea W. AU - Scheideler, Christian AU - Schmid, Stefan AU - Zhang, Jin ID - 623 T2 - Proceedings of the 31st Annual ACM SIGACT-SIGOPS Symposium on Principles and Distributed Computing (PODC) TI - Competitive and fair throughput for co-existing networks under adversarial interference ER - TY - CONF AB - This paper initiates the study of self-adjusting distributed data structures for networks. In particular, we present SplayNets: a binary search tree based network that is self-adjusting to routing request.We derive entropy bounds on the amortized routing cost and show that our splaying algorithm has some interesting properties. AU - Schmid, Stefan AU - Avin, Chen AU - Scheideler, Christian AU - Häupler, Bernhard AU - Lotker, Zvi ID - 625 T2 - Proceedings of the 26th International Symposium on Distributed Computing (DISC) TI - Brief Announcement: SplayNets - Towards Self-Adjusting Distributed Data Structures ER - TY - CONF AB - The design of ecient search structures for peer-to-peer systems has attracted a lot of attention in recent years. In this announcement we address the problem of nding the predecessor in a key set and present an ecient data structure called hashed Predecessor Patricia trie. Our hashed Predecessor Patricia trie supports PredecessorSearch(x) and Insert(x) and Delete(x) in O(log log u) hash table accesses when u is the size of the universe of the keys. That is the costs only depend on u and not the size of the data structure. One feature of our approach is that it only uses the lookup interface of the hash table and therefore hash table accesses may be realized by any distributed hash table (DHT). AU - Kniesburges, Sebastian AU - Scheideler, Christian ID - 626 T2 - Proceedings of the 26th International Symposium on Distributed Computing (DISC) TI - Brief Announcement: Hashed Predecessor Patricia Trie - A Data Structure for Efficient Predecessor Queries in Peer-to-Peer Systems ER - TY - CONF AB - Given an integer h, a graph G = (V;E) with arbitrary positive edge capacities and k pairs of vertices (s1; t1); (s2; t2); : : : ; (sk; tk), called terminals, an h-route cut is a set F µ E of edges such that after the removal of the edges in F no pair si ¡ ti is connected by h edge-disjoint paths (i.e., the connectivity of every si ¡ ti pair is at most h ¡ 1 in (V;E n F)). The h-route cut is a natural generalization of the classical cut problem for multicommodity °ows (take h = 1). The main result of this paper is an O(h722h log2 k)-approximation algorithm for the minimum h-route cut problem in the case that s1 = s2 = ¢ ¢ ¢ = sk, called the single source case. As a corollary of it we obtain an approximate duality theorem for multiroute multicom-modity °ows and cuts with a single source. This partially answers an open question posted in several previous papers dealing with cuts for multicommodity multiroute problems. AU - Kolman, Petr AU - Scheideler, Christian ID - 632 T2 - Proceedings of the 23th ACM SIAM Symposium on Discrete Algorithms (SODA) TI - Approximate Duality of Multicommodity Multiroute Flows and Cuts: Single Source Case ER - TY - CONF AB - Small-world networks have received significant attention because of their potential as models for the interaction networks of complex systems. Specifically, neither random networks nor regular lattices seem to be an adequate framework within which to study real-world complex systems such as chemical-reaction networks, neural networks, food webs, social networks, scientific-collaboration networks, and computer networks. Small-world networks provide some desired properties like an expected polylogarithmic distance between two processes in the network, which allows routing in polylogarithmic hops by simple greedy routing, and robustness against attacks or failures. By these properties, small-world networks are possible solutions for large overlay networks comparable to structured overlay networks like CAN, Pastry, Chord, which also provide polylogarithmic routing, but due to their uniform structure, structured overlay networks are more vulnerable to attacks or failures. In this paper we bring together a randomized process converging to a small-world network and a self-stabilization process so that a small-world network is formed out of any weakly connected initial state. To the best of our knowledge this is the first distributed self-stabilization process for building a small-world network. AU - Kniesburges, Sebastian AU - Koutsopoulos, Andreas AU - Scheideler, Christian ID - 640 T2 - Proceedings of the 26th IEEE International Parallel and Distributed Processing Symposium (IPDPS) TI - A Self-Stabilization Process for Small-World Networks ER - TY - JOUR AU - W. Richa, Andr{\'{e}}a AU - Scheideler, Christian AU - Schmid, Stefan AU - Zhang, Jin ID - 1868 IS - 3 JF - Distributed Computing TI - Competitive throughput in multi-hop wireless networks despite adaptive jamming ER - TY - JOUR AU - Mohd Nor, Rizal AU - Nesterenko, Mikhail AU - Scheideler, Christian ID - 1870 JF - Theor. Comput. Sci. TI - Corona: A stabilizing deterministic message-passing skip list ER - TY - JOUR AU - W. Richa, Andrea AU - Scheideler, Christian AU - Schmid, Stefan AU - Zhang, Jin ID - 1871 IS - 3 JF - IEEE/ACM Trans. Netw. TI - An Efficient and Fair MAC Protocol Robust to Reactive Interference ER - TY - JOUR AB - An elementary h-route ow, for an integer h 1, is a set of h edge- disjoint paths between a source and a sink, each path carrying a unit of ow, and an h-route ow is a non-negative linear combination of elementary h-routeows. An h-route cut is a set of edges whose removal decreases the maximum h-route ow between a given source-sink pair (or between every source-sink pair in the multicommodity setting) to zero. The main result of this paper is an approximate duality theorem for multicommodity h-route cuts and ows, for h 3: The size of a minimum h-route cut is at least f=h and at most O(log4 k f) where f is the size of the maximum h-routeow and k is the number of commodities. The main step towards the proof of this duality is the design and analysis of a polynomial-time approximation algorithm for the minimum h-route cut problem for h = 3 that has an approximation ratio of O(log4 k). Previously, polylogarithmic approximation was known only for h-route cuts for h 2. A key ingredient of our algorithm is a novel rounding technique that we call multilevel ball-growing. Though the proof of the duality relies on this algorithm, it is not a straightforward corollary of it as in the case of classical multicommodity ows and cuts. Similar results are shown also for the sparsest multiroute cut problem. AU - Kolman, Petr AU - Scheideler, Christian ID - 476 IS - 2 JF - Theory of Computing Systems TI - Towards Duality of Multicommodity Multiroute Cuts and Flows: Multilevel Ball-Growing ER - TY - CONF AB - This paper initiates the study of self-adjusting networks (or distributed data structures) whose topologies dynamically adapt to a communication pattern $\sigma$. We present a fully decentralized self-adjusting solution called SplayNet. A SplayNet is a distributed generalization of the classic splay tree concept. It ensures short paths (which can be found using local-greedy routing) between communication partners while minimizing topological rearrangements. We derive an upper bound for the amortized communication cost of a SplayNet based on empirical entropies of $\sigma$, and show that SplayNets have several interesting convergence properties. For instance, SplayNets features a provable online optimality under special requests scenarios. We also investigate the optimal static network and prove different lower bounds for the average communication cost based on graph cuts and on the empirical entropy of the communication pattern $\sigma$. From these lower bounds it follows, e.g., that SplayNets are optimal in scenarios where the requests follow a product distribution as well. Finally, this paper shows that in contrast to the Minimum Linear Arrangement problem which is generally NP-hard, the optimal static tree network can be computed in polynomial time for any guest graph, despite the exponentially large graph family. We complement our formal analysis with a small simulation study on a Facebook graph. AU - Avin, Chen AU - Häupler, Bernhard AU - Lotker, Zvi AU - Scheideler, Christian AU - Schmid, Stefan ID - 513 T2 - Proceedings of the 27th IEEE International Parallel and Distributed Processing Symposium (IPDPS) TI - Locally Self-Adjusting Tree Networks ER - TY - CONF AB - In this work we present the first scalable distributed information system,i.e., a system with low storage overhead, that is provably robust againstDenial-of-Service (DoS) attacks by a current insider. We allow acurrent insider to have complete knowledge about the information systemand to have the power to block any \epsilon-fraction of its serversby a DoS-attack, where \epsilon can be chosen up to a constant. The taskof the system is to serve any collection of lookup requests with at most oneper non-blocked server in an efficient way despite this attack. Previously,scalable solutions were only known for DoS-attacks of past insiders, where apast insider only has complete knowledge about some past time pointt_0 of the information system. Scheideler et al. (DISC 2007, SPAA 2009) showedthat in this case it is possible to design an information system so that anyinformation that was inserted or last updated after t_0 is safe against a DoS-attack. But their constructions would not work at all for a current insider. The key idea behindour IRIS system is to make extensive use of coding. More precisely, we presenttwo alternative distributed coding strategies with an at most logarithmicstorage overhead that can handle up to a constant fraction of blocked servers. AU - Eikel, Martina AU - Scheideler, Christian ID - 519 T2 - Proceedings of the 25th ACM Symposium on Parallelism in Algorithms and Architectures (SPAA) TI - IRIS: A Robust Information System Against Insider DoS-Attacks ER - TY - CONF AB - We consider the problem of managing a dynamic heterogeneous storagesystem in a distributed way so that the amount of data assigned to a hostin that system is related to its capacity. Two central problems have to be solvedfor this: (1) organizing the hosts in an overlay network with low degree and diameterso that one can efficiently check the correct distribution of the data androute between any two hosts, and (2) distributing the data among the hosts so thatthe distribution respects the capacities of the hosts and can easily be adapted asthe set of hosts or their capacities change. We present distributed protocols forthese problems that are self-stabilizing and that do not need any global knowledgeabout the system such as the number of nodes or the overall capacity of thesystem. Prior to this work no solution was known satisfying these properties. AU - Kniesburges, Sebastian AU - Koutsopoulos, Andreas AU - Scheideler, Christian ID - 542 T2 - Proceedings of the 27th International Symposium on Distributed Computing (DISC) TI - CONE-DHT: A distributed self-stabilizing algorithm for a heterogeneous storage system ER - TY - CONF AB - We consider the problem of resource discovery in distributed systems. In particular we give an algorithm, such that each node in a network discovers the add ress of any other node in the network. We model the knowledge of the nodes as a virtual overlay network given by a directed graph such that complete knowledge of all nodes corresponds to a complete graph in the overlay network. Although there are several solutions for resource discovery, our solution is the first that achieves worst-case optimal work for each node, i.e. the number of addresses (O(n)) or bits (O(nlogn)) a node receives or sendscoincides with the lower bound, while ensuring only a linearruntime (O(n)) on the number of rounds. AU - Kniesburges, Sebastian AU - Koutsopoulos, Andreas AU - Scheideler, Christian ID - 564 T2 - Proceedings of 20th International Colloqium on Structural Information and Communication Complexity (SIROCCO) TI - A Deterministic Worst-Case Message Complexity Optimal Solution for Resource Discovery ER - TY - CONF AB - In this work we present the first distributed storage system that is provably robust against crash failures issued by an adaptive adversary, i.e., for each batch of requests the adversary can decide based on the entire system state which servers will be unavailable for that batch of requests. Despite up to \gamma n^{1/\log\log n} crashed servers, with \gamma>0 constant and n denoting the number of servers, our system can correctly process any batch of lookup and write requests (with at most a polylogarithmic number of requests issued at each non-crashed server) in at most a polylogarithmic number of communication rounds, with at most polylogarithmic time and work at each server and only a logarithmic storage overhead. Our system is based on previous work by Eikel and Scheideler (SPAA 2013), who presented IRIS, a distributed information system that is provably robust against the same kind of crash failures. However, IRIS is only able to serve lookup requests. Handling both lookup and write requests has turned out to require major changes in the design of IRIS. AU - Scheideler, Christian AU - Setzer, Alexander AU - Eikel, Martina ID - 371 T2 - Proceedings of the 18th International Conference on Principles of Distributed Systems (OPODIS) TI - RoBuSt: A Crash-Failure-Resistant Distributed Storage System ER - TY - JOUR AB - The Chord peer-to-peer system is considered, together with CAN, Tapestry and Pastry, as one of the pioneering works on peer-to-peer distributed hash tables (DHT) that inspired a large volume of papers and projects on DHTs as well as peer-to-peer systems in general. Chord, in particular, has been studied thoroughly, and many variants of Chord have been presented that optimize various criteria. Also, several implementations of Chord are available on various platforms. Though Chord is known to be very efficient and scalable and it can handle churn quite well, no protocol is known yet that guarantees that Chord is self-stabilizing, i.e., the Chord network can be recovered from any initial state in which the network is still weakly connected. This is not too surprising since it is known that the Chord network is not locally checkable for its current topology. We present a slight extension of the Chord network, called Re-Chord (reactive Chord), that turns out to be locally checkable, and we present a self-stabilizing distributed protocol for it that can recover the Re-Chord network from any initial state, in which the n peers are weakly connected, in O(nlogn) communication rounds. We also show that our protocol allows a new peer to join or an old peer to leave an already stable Re-Chord network so that within O(logn)^2) communication rounds the Re-Chord network is stable again. AU - Kniesburges, Sebastian AU - Koutsopoulos, Andreas AU - Scheideler, Christian ID - 378 IS - 3 JF - Theory of Computing Systems TI - Re-Chord: A Self-stabilizing Chord Overlay Network ER - TY - JOUR AB - This article studies the design of medium access control (MAC) protocols for wireless networks that are provably robust against arbitrary and unpredictable disruptions (e.g., due to unintentional external interference from co-existing networks or due to jamming). We consider a wireless network consisting of a set of n honest and reliable nodes within transmission (and interference) range of each other, and we model the external disruptions with a powerful adaptive adversary. This adversary may know the protocol and its entire history and can use this knowledge to jam the wireless channel at will at any time. It is allowed to jam a (1 − )-fraction of the timesteps, for an arbitrary constant > 0 unknown to the nodes. The nodes cannot distinguish between the adversarial jamming or a collision of two or more messages that are sent at the same time. We demonstrate, for the first time, that there is a local-control MAC protocol requiring only very limited knowledge about the adversary and the network that achieves a constant (asymptotically optimal) throughput for the nonjammed time periods under any of the aforementioned adversarial strategies. The derived principles are also useful to build robust applications on top of the MAC layer, and we present an exemplary study for leader election, one of the most fundamental tasks in distributed computing. AU - Awerbuch, Baruch AU - Richa, Andrea W. AU - Scheideler, Christian AU - Schmid, Stefan AU - Zhang, Jin ID - 387 IS - 4 JF - Transactions on Algorithms TI - Principles of Robust Medium Access and an Application to Leader Election ER - TY - JOUR AU - Jacob, Riko AU - W. Richa, Andrea AU - Scheideler, Christian AU - Schmid, Stefan AU - Täubig, Hanjo ID - 1858 IS - 6 JF - J. ACM TI - SKIP*: A Self-Stabilizing Skip Graph ER - TY - CONF AU - Derakhshandeh, Zahra AU - Dolev, Shlomi AU - Gmyr, Robert AU - W. Richa, Andrea AU - Scheideler, Christian AU - Strothmann, Thim Frederik ID - 1863 SN - 978-1-4503-2821-0 T2 - 26th ACM Symposium on Parallelism in Algorithms and Architectures, SPAA'14, Prague, Czech Republic - June 23 - 25, 2014 TI - Brief announcement: amoebot - a new model for programmable matter ER - TY - CONF AB - This paper considers the problem of how to efficiently share a wireless medium which is subject to harsh external interference or even jamming. While this problem has already been studied intensively for simplistic single-hop or unit disk graph models, we make a leap forward and study MAC protocols for the SINR interference model (a.k.a. the physical model). We make two contributions. First, we introduce a new adversarial SINR model which captures a wide range of interference phenomena. Concretely, we consider a powerful, adaptive adversary which can jam nodes at arbitrary times and which is only limited by some energy budget. The second contribution of this paper is a distributed MAC protocol which provably achieves a constant competitive throughput in this environment: we show that, with high probability, the protocol ensures that a constant fraction of the non-blocked time periods is used for successful transmissions. AU - Ogierman, Adrian AU - Richa, Andrea W. AU - Scheideler, Christian AU - Schmid, Stefan AU - Zhang, Jin ID - 446 T2 - Proceedings of the 33rd Annual IEEE International Conference on Computer Communications (INFOCOM) TI - Competitive MAC under adversarial SINR ER - TY - CONF AB - In this survey article, we discuss two algorithmic research areas that emerge from problems that arise when resources are offered in the cloud. The first area, online leasing, captures problems arising from the fact that resources in the cloud are not bought, but leased by cloud vendors. The second area, Distributed Storage Systems, deals with problems arising from so-called cloud federations, i.e., when several cloud providers are needed to fulfill a given task. AU - Kniesburges, Sebastian AU - Markarian, Christine AU - Meyer auf der Heide, Friedhelm AU - Scheideler, Christian ID - 459 T2 - Proceedings of the 21st International Colloquium on Structural Information and Communication Complexity (SIROCCO) TI - Algorithmic Aspects of Resource Management in the Cloud ER - TY - JOUR AB - Topological self-stabilization is an important concept to build robust open distributed systems (such as peer-to-peer systems) where nodes can organize themselves into meaningful network topologies. The goal is to devise distributed algorithms where nodes forward, insert, and delete links to neighboring nodes, and that converge quickly to such a desirable topology, independently of the initial network configuration. This article proposes a new model to study the parallel convergence time. Our model sheds light on the achievable parallelism by avoiding bottlenecks of existing models that can yield a distorted picture. As a case study, we consider local graph linearization—i.e., how to build a sorted list of the nodes of a connected graph in a distributed and self-stabilizing manner. In order to study the main structure and properties of our model, we propose two variants of a most simple local linearization algorithm. For each of these variants, we present analyses of the worst-case and bestcase parallel time complexities, as well as the performance under a greedy selection of the actions to be executed. It turns out that the analysis is non-trivial despite the simple setting, and to complement our formal insights we report on our experiments which indicate that the runtimes may be better in the average case. AU - Gall, Dominik AU - Jacob, Riko AU - Richa, Andrea W. AU - Scheideler, Christian AU - Schmid, Stefan AU - Täubig, Hanjo ID - 464 IS - 1 JF - Theory of Computing Systems TI - A Note on the Parallel Runtime of Self-Stabilizing Graph Linearization ER - TY - CONF AB - A fundamental problem for peer-to-peer systems is to maintain connectivity while nodes are leaving, i.e., the nodes requesting to leave the peer-to-peer system are excluded from the overlay network without affecting its connectivity. There are a number of studies for safe node exclusion if the overlay is in a well-defined state initially. Surprisingly, the problem is not formally studied yet for the case in which the overlay network is in an arbitrary initial state, i.e., when looking for a self-stabilizing solution for excluding leaving nodes. We study this problem in two variants: the Finite Departure Problem (FDP) ) and the Finite Sleep Problem (FSP). In the FDP the leaving nodes have to irrevocably decide when it is safe to leave the network, whereas in the FSP, this leaving decision does not have to be final: the nodes may resume computation if necessary. We show that there is no self-stabilizing distributed algorithm for the FDP, even in a synchronous message passing model. To allow a solution, we introduce an oracle called NIDEC and show that it is sufficient even for the asynchronous message passing model by proposing an algorithm that can solve the FDP using NIDEC. We also show that a solution to the FSP does not require an oracle. AU - Foreback, Dianne AU - Koutsopoulos, Andreas AU - Nesterenko, Mikhail AU - Scheideler, Christian AU - Strothmann, Thim Frederik ID - 393 T2 - Proceedings of the 16th International Symposium on Stabilization, Safety, and Security of Distributed Systems TI - On Stabilizing Departures in Overlay Networks ER -