@inproceedings{397, abstract = {{We present a factor $14D^2$ approximation algorithm for the minimum linear arrangement problem on series-parallel graphs, where $D$ is the maximum degree in the graph. Given a suitable decomposition of the graph, our algorithm runs in time $O(|E|)$ and is very easy to implement. Its divide-and-conquer approach allows for an effective parallelization. Note that a suitable decomposition can also be computed in time $O(|E|\log{|E|})$ (or even $O(\log{|E|}\log^*{|E|})$ on an EREW PRAM using $O(|E|)$ processors). For the proof of the approximation ratio, we use a sophisticated charging method that uses techniques similar to amortized analysis in advanced data structures. On general graphs, the minimum linear arrangement problem is known to be NP-hard. To the best of our knowledge, the minimum linear arrangement problem on series-parallel graphs has not been studied before.}}, author = {{Scheideler, Christian and Eikel, Martina and Setzer, Alexander}}, booktitle = {{Proceedings of the 12th Workshop on Approximation and Online Algorithms (WAOA)}}, pages = {{168----180}}, title = {{{Minimum Linear Arrangement of Series-Parallel Graphs}}}, year = {{2014}}, } @inproceedings{412, abstract = {{In this paper we present and analyze HSkip+, a self-stabilizing overlay network for nodes with arbitrary heterogeneous bandwidths. HSkip+ has the same topology as the Skip+ graph proposed by Jacob et al. [PODC 2009] but its self-stabilization mechanism significantly outperforms the self-stabilization mechanism proposed for Skip+. Also, the nodes are now ordered according to their bandwidths and not according to their identifiers. Various other solutions have already been proposed for overlay networks with heterogeneous bandwidths, but they are not self-stabilizing. In addition to HSkip+ being self-stabilizing, its performance is on par with the best previous bounds on the time and work for joining or leaving a network of peers of logarithmic diameter and degree and arbitrary bandwidths. Also, the dilation and congestion for routing messages is on par with the best previous bounds for such networks, so that HSkip+ combines the advantages of both worlds. Our theoretical investigations are backed by simulations demonstrating that HSkip+ is indeed performing much better than Skip+ and working correctly under high churn rates.}}, author = {{Feldotto, Matthias and Scheideler, Christian and Graffi, Kalman}}, booktitle = {{Proceedings of the 14th IEEE International Conference on Peer-to-Peer Computing (P2P)}}, pages = {{1--10}}, title = {{{HSkip+: A Self-Stabilizing Overlay Network for Nodes with Heterogeneous Bandwidths}}}, doi = {{10.1109/P2P.2014.6934300}}, year = {{2014}}, } @article{284, abstract = {{In this work, we present the first scalable distributed information system, that is, a system with low storage overhead, that is provably robust against denial-of-service (DoS) attacks by a current insider. We allow a current insider to have complete knowledge about the information system and to have the power to block any ϵ-fraction of its servers by a DoS attack, where ϵ can be chosen up to a constant. The task of the system is to serve any collection of lookup requests with at most one per nonblocked server in an efficient way despite this attack. Previously, scalable solutions were only known for DoS attacks of past insiders, where a past insider only has complete knowledge about some past time point t0 of the information system. Scheideler et al. [Awerbuch and Scheideler 2007; Baumgart et al. 2009] showed that in this case, it is possible to design an information system so that any information that was inserted or last updated after t0 is safe against a DoS attack. But their constructions would not work at all for a current insider. The key idea behind our IRIS system is to make extensive use of coding. More precisely, we present two alternative distributed coding strategies with an at most logarithmic storage overhead that can handle up to a constant fraction of blocked servers.}}, author = {{Eikel, Martina and Scheideler, Christian}}, journal = {{Transactions on Parallel Computing}}, number = {{3}}, pages = {{18:1----18:33}}, publisher = {{ACM}}, title = {{{IRIS: A Robust Information System Against Insider DoS Attacks}}}, doi = {{10.1145/2809806}}, year = {{2015}}, } @inproceedings{241, abstract = {{Distributed applications are commonly based on overlay networks interconnecting their sites so that they can exchange information. For these overlay networks to preserve their functionality, they should be able to recover from various problems like membership changes or faults. Various self-stabilizing overlay networks have already been proposed in recent years, which have the advantage of being able to recover from any illegal state, but none of these networks can give any guarantees on its functionality while the recovery process is going on. We initiate research on overlay networks that are not only self-stabilizing but that also ensure that searchability is maintained while the recovery process is going on, as long as there are no corrupted messages in the system. More precisely, once a search message from node u to another node v is successfully delivered, all future search messages from u to v succeed as well. We call this property monotonic searchability. We show that in general it is impossible to provide monotonic searchability if corrupted messages are present in the system, which justifies the restriction to system states without corrupted messages. Furthermore, we provide a self-stabilizing protocol for the line for which we can also show monotonic searchability. It turns out that even for the line it is non-trivial to achieve this property. Additionally, we extend our protocol to deal with node departures in terms of the Finite Departure Problem of Foreback et. al (SSS 2014). This makes our protocol even capable of handling node dynamics.}}, author = {{Scheideler, Christian and Setzer, Alexander and Strothmann, Thim Frederik}}, booktitle = {{Proceedings of the 19th International Conference on Principles of Distributed Systems (OPODIS)}}, title = {{{Towards Establishing Monotonic Searchability in Self-Stabilizing Data Structures}}}, doi = {{10.4230/LIPIcs.OPODIS.2015.24}}, year = {{2015}}, } @inproceedings{242, abstract = {{A fundamental problem for overlay networks is to safely exclude leaving nodes, i.e., the nodes requesting to leave the overlay network are excluded from it without affecting its connectivity. There are a number of studies for safe node exclusion if the overlay is in a well-defined state, but almost no formal results are known 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 when woken up by an incoming message. We are the first to present a self-stabilizing protocol for the FDP and the FSP that can be combined with a large class of overlay maintenance protocols so that these are then guaranteed to safely exclude leaving nodes from the system from any initial state while operating as specified for the staying nodes. In order to formally define the properties these overlay maintenance protocols have to satisfy, we identify four basic primitives for manipulating edges in an overlay network that might be of independent interest.}}, author = {{Koutsopoulos, Andreas and Scheideler, Christian and Strothmann, Thim Frederik}}, booktitle = {{Proceedings of the 17th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS)}}, pages = {{201--216}}, title = {{{Towards a Universal Approach for the Finite Departure Problem in Overlay Networks}}}, doi = {{10.1007/978-3-319-21741-3_14}}, year = {{2015}}, } @article{327, abstract = {{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 address 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)O(n)) or bits (O(nlog⁡n)O(nlog⁡n)) a node receives or sends coincides with the lower bound, while ensuring only a linear runtime (O(n)O(n)) on the number of rounds.}}, author = {{Kniesburges, Sebastian and Koutsopoulos, Andreas and Scheideler, Christian}}, journal = {{Theoretical Computer Science}}, pages = {{67--79}}, publisher = {{Elsevier}}, title = {{{A deterministic worst-case message complexity optimal solution for resource discovery}}}, doi = {{10.1016/j.tcs.2014.11.027}}, year = {{2015}}, } @inproceedings{1850, author = {{Derakhshandeh, Zahra and Gmyr, Robert and Strothmann, Thim Frederik and A. Bazzi, Rida and W. Richa, Andrea and Scheideler, Christian}}, booktitle = {{DNA Computing and Molecular Programming - 21st International Conference, DNA 21, Boston and Cambridge, MA, USA, August 17-21, 2015. Proceedings}}, isbn = {{978-3-319-21998-1}}, pages = {{117----132}}, title = {{{Leader Election and Shape Formation with Self-organizing Programmable Matter}}}, doi = {{10.1007/978-3-319-21999-8_8}}, volume = {{9211}}, year = {{2015}}, } @inproceedings{1851, author = {{Derakhshandeh, Zahra and Gmyr, Robert and W. Richa, Andrea and Scheideler, Christian and Strothmann, Thim Frederik}}, booktitle = {{Proceedings of the Second Annual International Conference on Nanoscale Computing and Communication, NANOCOM' 15, Boston, MA, USA, September 21-22, 2015}}, isbn = {{978-1-4503-3674-1}}, pages = {{21:1----21:2}}, publisher = {{ACM}}, title = {{{An Algorithmic Framework for Shape Formation Problems in Self-Organizing Particle Systems}}}, doi = {{10.1145/2800795.2800829}}, year = {{2015}}, } @inproceedings{1852, author = {{Derakhshandeh, Zahra and Gmyr, Robert and Strothmann, Thim Frederik and A. Bazzi, Rida and W. Richa, Andrea and Scheideler, Christian}}, booktitle = {{Proceedings of the 2015 ACM Symposium on Principles of Distributed Computing, PODC 2015, Donostia-San Sebasti{\'{a}}n, Spain, July 21 - 23, 2015}}, isbn = {{978-1-4503-3617-8}}, pages = {{67----69}}, publisher = {{ACM}}, title = {{{Brief Announcement: On the Feasibility of Leader Election and Shape Formation with Self-Organizing Programmable Matter}}}, doi = {{10.1145/2767386.2767451}}, year = {{2015}}, } @inproceedings{1853, author = {{Koutsopoulos, Andreas and Scheideler, Christian and Strothmann, Thim Frederik}}, booktitle = {{Proceedings of the 27th ACM on Symposium on Parallelism in Algorithms and Architectures, SPAA 2015, Portland, OR, USA, June 13-15, 2015}}, isbn = {{978-1-4503-3588-1}}, pages = {{77----79}}, publisher = {{ACM}}, title = {{{Brief Announcement: Towards a Universal Approach for the Finite Departure Problem in Overlay Networks}}}, doi = {{10.1145/2755573.2755614}}, year = {{2015}}, } @inproceedings{215, abstract = {{We present three robust overlay networks: First, we present a network that organizes the nodes into an expander and is resistant to even massive adversarial churn. Second, we develop a network based on the hypercube that maintains connectivity under adversarial DoS-attacks. For the DoS-attacks we use the notion of a Omega(log log n)-late adversary which only has access to topological information that is at least Omega(log log n) rounds old. Finally, we develop a network that combines both churn- and DoS-resistance. The networks gain their robustness through constant network reconfiguration, i.e., the topology of the networks changes constantly. Our reconguration algorithms are based on node sampling primitives for expanders and hypercubes that allow each node to sample a logarithmic number of nodes uniformly at random in O(log log n) communication rounds. These primitives are specific to overlay networks and their optimal runtime represents an exponential improvement over known techniques. Our results have a wide range of applications, for example in the area of scalable and robust peer-to-peer systems.}}, author = {{Drees, Maximilian and Gmyr, Robert and Scheideler, Christian}}, booktitle = {{Proceedings of the 28th ACM Symposium on Parallelism in Algorithms and Architectures (SPAA)}}, pages = {{417----427}}, title = {{{Churn- and DoS-resistant Overlay Networks Based on Network Reconfiguration}}}, doi = {{10.1145/2935764.2935783}}, year = {{2016}}, } @article{1835, author = {{Schmid, Stefan and Avin, Chen and Scheideler, Christian and Borokhovich, Michael and Haeupler, Bernhard and Lotker, Zvi}}, journal = {{IEEE/ACM Trans. Netw.}}, number = {{3}}, pages = {{1421----1433}}, title = {{{SplayNet: Towards Locally Self-Adjusting Networks}}}, doi = {{10.1109/TNET.2015.2410313}}, year = {{2016}}, } @inproceedings{1836, author = {{Derakhshandeh, Zahra and Gmyr, Robert and Porter, Alexandra and W. Richa, Andrea and Scheideler, Christian and Strothmann, Thim Frederik}}, booktitle = {{DNA Computing and Molecular Programming - 22nd International Conference, DNA 22, Munich, Germany, September 4-8, 2016, Proceedings}}, pages = {{148----164}}, title = {{{On the Runtime of Universal Coating for Programmable Matter}}}, doi = {{10.1007/978-3-319-43994-5_10}}, volume = {{9818}}, year = {{2016}}, } @inproceedings{1837, author = {{Derakhshandeh, Zahra and Gmyr, Robert and W. Richa, Andrea and Scheideler, Christian and Strothmann, Thim Frederik}}, booktitle = {{Proceedings of the 28th ACM Symposium on Parallelism in Algorithms and Architectures, SPAA 2016, Asilomar State Beach/Pacific Grove, CA, USA, July 11-13, 2016}}, pages = {{289----299}}, publisher = {{ACM}}, title = {{{Universal Shape Formation for Programmable Matter}}}, doi = {{10.1145/2935764.2935784}}, year = {{2016}}, } @inbook{1845, author = {{W. Richa, Andrea and Scheideler, Christian}}, booktitle = {{Encyclopedia of Algorithms}}, pages = {{999----1002}}, title = {{{Jamming-Resistant MAC Protocols for Wireless Networks}}}, doi = {{10.1007/978-1-4939-2864-4_593}}, year = {{2016}}, } @inproceedings{155, abstract = {{We present a self-stabilizing algorithm for overlay networks that, for an arbitrary metric given by a distance oracle, constructs the graph representing that metric. The graph representing a metric is the unique minimal undirected graph such that for any pair of nodes the length of a shortest path between the nodes corresponds to the distance between the nodes according to the metric. The algorithm works under both an asynchronous and a synchronous daemon. In the synchronous case, the algorithm stablizes in time O(n) and it is almost silent in that after stabilization a node sends and receives a constant number of messages per round.}}, author = {{Gmyr, Robert and Lefèvre, Jonas and Scheideler, Christian}}, booktitle = {{Proceedings of the 18th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS)}}, pages = {{248----262}}, title = {{{Self-stabilizing Metric Graphs}}}, doi = {{10.1007/978-3-319-49259-9_20}}, year = {{2016}}, } @inproceedings{142, abstract = {{For overlay networks, the ability to recover from a variety of problems like membership changes or faults is a key element to preserve their functionality. In recent years, various self-stabilizing overlay networks have been proposed that have the advantage of being able to recover from any illegal state. However, the vast majority of these networks cannot give any guarantees on its functionality while the recovery process is going on. We are especially interested in searchability, i.e., the functionality that search messages for a specific identifier are answered successfully if a node with that identifier exists in the network. We investigate overlay networks that are not only self-stabilizing but that also ensure that monotonic searchability is maintained while the recovery process is going on, as long as there are no corrupted messages in the system. More precisely, once a search message from node u to another node v is successfully delivered, all future search messages from u to v succeed as well. Monotonic searchability was recently introduced in OPODIS 2015, in which the authors provide a solution for a simple line topology.We present the first universal approach to maintain monotonic searchability that is applicable to a wide range of topologies. As the base for our approach, we introduce a set of primitives for manipulating overlay networks that allows us to maintain searchability and show how existing protocols can be transformed to use theses primitives.We complement this result with a generic search protocol that together with the use of our primitives guarantees monotonic searchability.As an additional feature, searching existing nodes with the generic search protocol is as fast as searching a node with any other fixed routing protocol once the topology has stabilized.}}, author = {{Scheideler, Christian and Setzer, Alexander and Strothmann, Thim Frederik}}, booktitle = {{Proceedings of the 30th International Symposium on Distributed Computing (DISC)}}, pages = {{71----84}}, title = {{{Towards a Universal Approach for Monotonic Searchability in Self-stabilizing Overlay Networks}}}, doi = {{10.1007/978-3-662-53426-7_6}}, year = {{2016}}, } @article{3872, abstract = {{This paper considers the problem of how to efficiently share a wireless medium which is subject to harsh external interference or even jamming. So far, this problem is understood only in simplistic single-hop or unit disk graph models. We in this paper initiate the study of MAC protocols for the SINR interference model (a.k.a. physical model). This paper makes 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. Our second contribution is a distributed MAC protocol called Sade 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.}}, author = {{Ogierman, Adrian and Richa, Andrea and Scheideler, Christian and Schmid, Stefan and Zhang, Jin}}, issn = {{0178-2770}}, journal = {{Distributed Computing}}, number = {{3}}, pages = {{241--254}}, publisher = {{Springer Nature}}, title = {{{Sade: competitive MAC under adversarial SINR}}}, doi = {{10.1007/s00446-017-0307-1}}, volume = {{31}}, year = {{2017}}, } @article{1812, author = {{Koutsopoulos, Andreas and Scheideler, Christian and Strothmann, Thim Frederik}}, journal = {{Inf. Comput.}}, pages = {{408----424}}, title = {{{Towards a universal approach for the finite departure problem in overlay networks}}}, doi = {{10.1016/j.ic.2016.12.006}}, year = {{2017}}, } @article{1813, author = {{P. Fekete, Sandor and W. Richa, Andrea and Römer, Kay and Scheideler, Christian}}, journal = {{SIGACT News}}, number = {{2}}, pages = {{87----94}}, title = {{{Algorithmic Foundations of Programmable Matter Dagstuhl Seminar 16271}}}, doi = {{10.1145/3106700.3106713}}, year = {{2017}}, }