TY - JOUR AU - Götte, Thorsten AU - Kolb, Christina AU - Scheideler, Christian AU - Werthmann, Julian ID - 43109 JF - Theor. Comput. Sci. TI - Beep-and-Sleep: Message and Energy Efficient Set Cover VL - 950 ER - TY - CONF AU - Werthmann, Julian AU - Scheideler, Christian AU - Coy, Sam AU - Czumaj, Artur AU - Schneider, Philipp ID - 45188 TI - Routing Schemes for Hybrid Communication Networks ER - TY - CONF AU - Dou, Jinfeng AU - Götte, Thorsten AU - Hillebrandt, Henning AU - Scheideler, Christian AU - Werthmann, Julian ID - 45193 T2 - Proc. of the 42nd ACM Symposium on Principles of Distributed Computing (PODC '23) TI - Brief Announcement: Distributed Construction of Near-Optimal Compact Routing Schemes for Planar Graphs ER - TY - JOUR AU - Götte, Thorsten AU - Hinnenthal, Kristian AU - Scheideler, Christian AU - Werthmann, Julian ID - 45192 JF - Distributed Computing TI - Time-Optimal Construction of Overlays ER - TY - CHAP AU - Götte, Thorsten AU - Knollmann, Till AU - Meyer auf der Heide, Friedhelm AU - Scheideler, Christian AU - Werthmann, Julian ED - Haake, Claus-Jochen ED - Meyer auf der Heide, Friedhelm ED - Platzner, Marco ED - Wachsmuth, Henning ED - Wehrheim, Heike ID - 45875 T2 - On-The-Fly Computing -- Individualized IT-services in dynamic markets TI - Capabilities and Limitations of Local Strategies in Dynamic Networks VL - 412 ER - TY - BOOK AB - In the proposal for our CRC in 2011, we formulated a vision of markets for IT services that describes an approach to the provision of such services that was novel at that time and, to a large extent, remains so today: „Our vision of on-the-fly computing is that of IT services individually and automatically configured and brought to execution from flexibly combinable services traded on markets. At the same time, we aim at organizing markets whose participants maintain a lively market of services through appropriate entrepreneurial actions.“ Over the last 12 years, we have developed methods and techniques to address problems critical to the convenient, efficient, and secure use of on-the-fly computing. Among other things, we have made the description of services more convenient by allowing natural language input, increased the quality of configured services through (natural language) interaction and more efficient configuration processes and analysis procedures, made the quality of (the products of) providers in the marketplace transparent through reputation systems, and increased the resource efficiency of execution through reconfigurable heterogeneous computing nodes and an integrated treatment of service description and configuration. We have also developed network infrastructures that have a high degree of adaptivity, scalability, efficiency, and reliability, and provide cryptographic guarantees of anonymity and security for market participants and their products and services. To demonstrate the pervasiveness of the OTF computing approach, we have implemented a proof-of-concept for OTF computing that can run typical scenarios of an OTF market. We illustrated the approach using a cutting-edge application scenario – automated machine learning (AutoML). Finally, we have been pushing our work for the perpetuation of On-The-Fly Computing beyond the SFB and sharing the expertise gained in the SFB in events with industry partners as well as transfer projects. This work required a broad spectrum of expertise. Computer scientists and economists with research interests such as computer networks and distributed algorithms, security and cryptography, software engineering and verification, configuration and machine learning, computer engineering and HPC, microeconomics and game theory, business informatics and management have successfully collaborated here. AU - Haake, Claus-Jochen AU - Meyer auf der Heide, Friedhelm AU - Platzner, Marco AU - Wachsmuth, Henning AU - Wehrheim, Heike ID - 45863 TI - On-The-Fly Computing -- Individualized IT-services in dynamic markets VL - 412 ER - TY - CONF AB - The famous $k$-Server Problem covers plenty of resource allocation scenarios, and several variations have been studied extensively for decades. However, to the best of our knowledge, no research has considered the problem if the servers are not identical and requests can express which specific servers should serve them. Therefore, we present a new model generalizing the $k$-Server Problem by *preferences* of the requests and proceed to study it in a uniform metric space for deterministic online algorithms (the special case of paging). In our model, requests can either demand to be answered by any server (*general requests*) or by a specific one (*specific requests*). If only general requests appear, the instance is one of the original $k$-Server Problem, and a lower bound for the competitive ratio of $k$ applies. If only specific requests appear, a solution with a competitive ratio of $1$ becomes trivial since there is no freedom regarding the servers' movements. Perhaps counter-intuitively, we show that if both kinds of requests appear, the lower bound raises to $2k-1$. We study deterministic online algorithms in uniform metrics and present two algorithms. The first one has an adaptive competitive ratio dependent on the frequency of specific requests. It achieves a worst-case competitive ratio of $3k-2$ while it is optimal when only general or only specific requests appear (competitive ratio of $k$ and $1$, respectively). The second has a fixed close-to-optimal worst-case competitive ratio of $2k+14$. For the first algorithm, we show a lower bound of $3k-2$, while the second algorithm has a lower bound of $2k-1$ when only general requests appear. The two algorithms differ in only one behavioral rule for each server that significantly influences the competitive ratio. Each server acting according to the rule allows approaching the worst-case lower bound, while it implies an increased lower bound for $k$-Server instances. In other words, there is a trade-off between performing well against instances of the $k$-Server Problem and instances containing specific requests. We also show that no deterministic online algorithm can be optimal for both kinds of instances simultaneously. AU - Castenow, Jannik AU - Feldkord, Björn AU - Knollmann, Till AU - Malatyali, Manuel AU - Meyer auf der Heide, Friedhelm ID - 31847 KW - K-Server Problem KW - Heterogeneity KW - Online Caching SN - 9781450391467 T2 - Proceedings of the 34th ACM Symposium on Parallelism in Algorithms and Architectures TI - The k-Server with Preferences Problem ER - TY - CONF AU - Padalkin, Andreas AU - Scheideler, Christian AU - Warner, Daniel ED - Ouldridge, Thomas E. ED - Wickham, Shelley F. J. ID - 32602 SN - 1868-8969 T2 - 28th International Conference on DNA Computing and Molecular Programming (DNA 28) TI - The Structural Power of Reconfigurable Circuits in the Amoebot Model VL - 238 ER - TY - JOUR AU - Baswana, Surender AU - Gupta, Shiv AU - Knollmann, Till ID - 31479 JF - Algorithmica KW - Applied Mathematics KW - Computer Science Applications KW - General Computer Science SN - 0178-4617 TI - Mincut Sensitivity Data Structures for the Insertion of an Edge ER - TY - CONF AU - Daymude, Joshua J. AU - Richa, Andréa W. AU - Scheideler, Christian ED - Aspnes, James ED - Michail, Othon ID - 33230 T2 - 1st Symposium on Algorithmic Foundations of Dynamic Networks, SAND 2022, March 28-30, 2022, Virtual Conference TI - Local Mutual Exclusion for Dynamic, Anonymous, Bounded Memory Message Passing Systems VL - 221 ER - TY - CONF AU - Aguiliera, Marcos AU - Richa, Andréa W. AU - Schwarzmann, Alexander A. AU - Panconesi, Alessandro AU - Scheideler, Christian AU - Woelfel, Philipp ED - Milani, Alessia ED - Woelfel, Philipp ID - 33967 T2 - PODC ’22: ACM Symposium on Principles of Distributed Computing, Salerno, Italy, July 25 - 29, 2022 TI - 2022 Edsger W. Dijkstra Prize in Distributed Computing ER - TY - GEN ED - Scheideler, Christian ID - 33968 SN - 978-3-95977-255-6 TI - 36th International Symposium on Distributed Computing, DISC 2022, October 25-27, 2022, Augusta, Georgia, USA VL - 246 ER - TY - JOUR AB - While many research in distributed computing has covered solutions for self-stabilizing computing and topologies, there is far less work on self-stabilization for distributed data structures. However, when peers in peer-to-peer networks crash, a distributed data structure may not remain intact. We present a self-stabilizing protocol for a distributed data structure called the Hashed Patricia Trie (Kniesburges and Scheideler WALCOM'11) that enables efficient prefix search on a set of keys. The data structure has many applications while offering low overhead and efficient operations when embedded on top of a Distributed Hash Table. Especially, longest prefix matching for x can be done in O(log |x|) hash table read accesses. We show how to maintain the structure in a self-stabilizing way, while assuring a low overhead in a legal state and an asymptotically optimal memory demand of O(d) bits, where d is the number of bits needed for storing all keys. AU - Knollmann, Till AU - Scheideler, Christian ID - 21096 JF - Information and Computation SN - 0890-5401 TI - A self-stabilizing Hashed Patricia Trie ER - TY - JOUR AU - Feldkord, Björn AU - Knollmann, Till AU - Malatyali, Manuel AU - Meyer auf der Heide, Friedhelm ID - 20683 JF - Theory of Computing Systems TI - Managing Multiple Mobile Resources VL - 65 ER - TY - CONF AU - Bienkowski, Marcin AU - Feldkord, Björn AU - Schmidt, Pawel ID - 20817 T2 - Proceedings of the 38th Symposium on Theoretical Aspects of Computer Science (STACS) TI - A Nearly Optimal Deterministic Online Algorithm for Non-Metric Facility Location ER - TY - CONF AB - We show how to construct an overlay network of constant degree and diameter $O(\log n)$ in time $O(\log n)$ starting from an arbitrary weakly connected graph. We assume a synchronous communication network in which nodes can send messages to nodes they know the identifier of and establish new connections by sending node identifiers. If the initial network's graph is weakly connected and has constant degree, then our algorithm constructs the desired topology with each node sending and receiving only $O(\log n)$ messages in each round in time $O(\log n)$, w.h.p., which beats the currently best $O(\log^{3/2} n)$ time algorithm of [Götte et al., SIROCCO'19]. Since the problem cannot be solved faster than by using pointer jumping for $O(\log n)$ rounds (which would even require each node to communicate $\Omega(n)$ bits), our algorithm is asymptotically optimal. We achieve this speedup by using short random walks to repeatedly establish random connections between the nodes that quickly reduce the conductance of the graph using an observation of [Kwok and Lau, APPROX'14]. Additionally, we show how our algorithm can be used to efficiently solve graph problems in \emph{hybrid networks} [Augustine et al., SODA'20]. Motivated by the idea that nodes possess two different modes of communication, we assume that communication of the \emph{initial} edges is unrestricted. In contrast, only polylogarithmically many messages can be communicated over edges that have been established throughout an algorithm's execution. For an (undirected) graph $G$ with arbitrary degree, we show how to compute connected components, a spanning tree, and biconnected components in time $O(\log n)$, w.h.p. Furthermore, we show how to compute an MIS in time $O(\log d + \log \log n)$, w.h.p., where $d$ is the initial degree of $G$. AU - Götte, Thorsten AU - Hinnenthal, Kristian AU - Scheideler, Christian AU - Werthmann, Julian ED - Censor-Hillel, Keren ID - 22283 T2 - Proc. of the 40th ACM Symposium on Principles of Distributed Computing (PODC '21) TI - Time-Optimal Construction of Overlays ER - TY - CHAP AU - Götte, Thorsten AU - Kolb, Christina AU - Scheideler, Christian AU - Werthmann, Julian ID - 26888 SN - 0302-9743 T2 - Algorithms for Sensor Systems (ALGOSENSORS '21) TI - Beep-And-Sleep: Message and Energy Efficient Set Cover ER - TY - CONF AB - We consider a natural extension to the metric uncapacitated Facility Location Problem (FLP) in which requests ask for different commodities out of a finite set \( S \) of commodities. Ravi and Sinha (SODA 2004) introduced the model as the \emph{Multi-Commodity Facility Location Problem} (MFLP) and considered it an offline optimization problem. The model itself is similar to the FLP: i.e., requests are located at points of a finite metric space and the task of an algorithm is to construct facilities and assign requests to facilities while minimizing the construction cost and the sum over all assignment distances. In addition, requests and facilities are heterogeneous; they request or offer multiple commodities out of $S$. A request has to be connected to a set of facilities jointly offering the commodities demanded by it. In comparison to the FLP, an algorithm has to decide not only if and where to place facilities, but also which commodities to offer at each. To the best of our knowledge we are the first to study the problem in its online variant in which requests, their positions and their commodities are not known beforehand but revealed over time. We present results regarding the competitive ratio. On the one hand, we show that heterogeneity influences the competitive ratio by developing a lower bound on the competitive ratio for any randomized online algorithm of \( \Omega ( \sqrt{|S|} + \frac{\log n}{\log \log n} ) \) that already holds for simple line metrics. Here, \( n \) is the number of requests. On the other side, we establish a deterministic \( \mathcal{O}(\sqrt{|S|} \cdot \log n) \)-competitive algorithm and a randomized \( \mathcal{O}(\sqrt{|S|} \cdot \frac{\log n}{\log \log n} ) \)-competitive algorithm. Further, we show that when considering a more special class of cost functions for the construction cost of a facility, the competitive ratio decreases given by our deterministic algorithm depending on the function. AU - Castenow, Jannik AU - Feldkord, Björn AU - Knollmann, Till AU - Malatyali, Manuel AU - Meyer auf der Heide, Friedhelm ID - 17370 KW - Online Multi-Commodity Facility Location KW - Competitive Ratio KW - Online Optimization KW - Facility Location Problem SN - 9781450369350 T2 - Proceedings of the 32nd ACM Symposium on Parallelism in Algorithms and Architectures TI - The Online Multi-Commodity Facility Location Problem ER - TY - GEN ED - Werneck Richa, Andrea ED - Scheideler, Christian ID - 17836 SN - 978-3-030-54920-6 TI - Structural Information and Communication Complexity - 27th International Colloquium, SIROCCO 2020, Paderborn, Germany, June 29 - July 1, 2020, Proceedings VL - 12156 ER - TY - GEN ED - Scheideler, Christian ED - Spear, Michael ID - 17839 SN - 978-1-4503-6935-0 TI - SPAA '20: 32nd ACM Symposium on Parallelism in Algorithms and Architectures, Virtual Event, USA, July 15-17, 2020 ER - TY - CONF AB - We consider the problem of computing shortest paths in \emph{hybrid networks}, in which nodes can make use of different communication modes. For example, mobile phones may use ad-hoc connections via Bluetooth or Wi-Fi in addition to the cellular network to solve tasks more efficiently. Like in this case, the different communication modes may differ considerably in range, bandwidth, and flexibility. We build upon the model of Augustine et al. [SODA '20], which captures these differences by a \emph{local} and a \emph{global} mode. Specifically, the local edges model a fixed communication network in which $O(1)$ messages of size $O(\log n)$ can be sent over every edge in each synchronous round. The global edges form a clique, but nodes are only allowed to send and receive a total of at most $O(\log n)$ messages over global edges, which restricts the nodes to use these edges only very sparsely. We demonstrate the power of hybrid networks by presenting algorithms to compute Single-Source Shortest Paths and the diameter very efficiently in \emph{sparse graphs}. Specifically, we present exact $O(\log n)$ time algorithms for cactus graphs (i.e., graphs in which each edge is contained in at most one cycle), and $3$-approximations for graphs that have at most $n + O(n^{1/3})$ edges and arboricity $O(\log n)$. For these graph classes, our algorithms provide exponentially faster solutions than the best known algorithms for general graphs in this model. Beyond shortest paths, we also provide a variety of useful tools and techniques for hybrid networks, which may be of independent interest. AU - Feldmann, Michael AU - Hinnenthal, Kristian AU - Scheideler, Christian ID - 20755 T2 - Proceedings of the 24th International Conference on Principles of Distributed Systems (OPODIS) TI - Fast Hybrid Network Algorithms for Shortest Paths in Sparse Graphs ER - TY - JOUR AB - The maintenance of efficient and robust overlay networks is one of the most fundamental and reoccurring themes in networking. This paper presents a survey of state-of-the-art algorithms to design and repair overlay networks in a distributed manner. In particular, we discuss basic algorithmic primitives to preserve connectivity, review algorithms for the fundamental problem of graph linearization, and then survey self-stabilizing algorithms for metric and scalable topologies. We also identify open problems and avenues for future research. AU - Feldmann, Michael AU - Scheideler, Christian AU - Schmid, Stefan ID - 16902 JF - ACM Computing Surveys TI - Survey on Algorithms for Self-Stabilizing Overlay Networks ER - TY - CONF AU - Castenow, Jannik AU - Kolb, Christina AU - Scheideler, Christian ID - 15169 T2 - Proceedings of the 21st International Conference on Distributed Computing and Networking (ICDCN) TI - A Bounding Box Overlay for Competitive Routing in Hybrid Communication Networks ER - TY - JOUR AU - Karl, Holger AU - Kundisch, Dennis AU - Meyer auf der Heide, Friedhelm AU - Wehrheim, Heike ID - 13770 IS - 6 JF - Business & Information Systems Engineering TI - A Case for a New IT Ecosystem: On-The-Fly Computing VL - 62 ER - TY - CONF AB - Self-stabilizing overlay networks have the advantage of being able to recover from illegal states and faults. However, the majority of these networks cannot give any guarantees on their functionality while the recovery process is going on. We are especially interested in searchability, i.e., the functionality that search messages for a specific node are answered successfully if a node exists in the network. In this paper we investigate overlay networks that ensure the maintenance of monotonic searchability while the self-stabilization is going on. 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 extend the existing research by focusing on skip graphs and present a solution for two scenarios: (i) the goal topology is a super graph of the perfect skip graph and (ii) the goal topology is exactly the perfect skip graph. AU - Luo, Linghui AU - Scheideler, Christian AU - Strothmann, Thim Frederik ID - 7636 T2 - Proceedings of the 2019 IEEE 33rd International Parallel and Distributed Processing Symposium (IPDPS '19) TI - MultiSkipGraph: A Self-stabilizing Overlay Network that Maintains Monotonic Searchability ER - TY - CONF AB - We propose two protocols for distributed priority queues (denoted by 'heap' for simplicity in this paper) called SKEAP and SEAP. SKEAP realizes a distributed heap for a constant amount of priorities and SEAP one for an arbitrary amount. Both protocols build on an overlay, which induces an aggregation tree on which heap operations are aggregated in batches, ensuring that our protocols scale even for a high rate of incoming requests. As part of SEAP we provide a novel distributed protocol for the k-selection problem that runs in time O(log n) w.h.p. SKEAP guarantees sequential consistency for its heap operations, while SEAP guarantees serializability. SKEAP and SEAP provide logarithmic runtimes w.h.p. on all their operations. SKEAP and SEAP provide logarithmic runtimes w.h.p. on all their operations with SEAP having to use only O(log n) bit messages. AU - Feldmann, Michael AU - Scheideler, Christian ID - 8534 T2 - Proceedings of the 31st ACM Symposium on Parallelism in Algorithms and Architectures (SPAA) TI - Skeap & Seap: Scalable Distributed Priority Queues for Constant and Arbitrary Priorities ER - TY - CONF AU - Augustine, John AU - Ghaffari, Mohsen AU - Gmyr, Robert AU - Hinnenthal, Kristian AU - Kuhn, Fabian AU - Li, Jason AU - Scheideler, Christian ID - 8871 T2 - Proceedings of the 31st ACM Symposium on Parallelism in Algorithms and Architectures TI - Distributed Computation in Node-Capacitated Networks ER - TY - CONF AB - We consider the problem of transforming a given graph G_s into a desired graph G_t by applying a minimum number of primitives from a particular set of local graph transformation primitives. These primitives are local in the sense that each node can apply them based on local knowledge and by affecting only its 1-neighborhood. Although the specific set of primitives we consider makes it possible to transform any (weakly) connected graph into any other (weakly) connected graph consisting of the same nodes, they cannot disconnect the graph or introduce new nodes into the graph, making them ideal in the context of supervised overlay network transformations. We prove that computing a minimum sequence of primitive applications (even centralized) for arbitrary G_s and G_t is NP-hard, which we conjecture to hold for any set of local graph transformation primitives satisfying the aforementioned properties. On the other hand, we show that this problem admits a polynomial time algorithm with a constant approximation ratio. AU - Scheideler, Christian AU - Setzer, Alexander ID - 10586 KW - Graphs transformations KW - NP-hardness KW - approximation algorithms T2 - Proceedings of the 46th International Colloquium on Automata, Languages, and Programming TI - On the Complexity of Local Graph Transformations VL - 132 ER - TY - CONF AU - Feldkord, Björn AU - Knollmann, Till AU - Malatyali, Manuel AU - Meyer auf der Heide, Friedhelm ID - 12870 T2 - Proceedings of the 17th Workshop on Approximation and Online Algorithms (WAOA) TI - Managing Multiple Mobile Resources ER - TY - CONF AU - Augustine, John AU - Hinnenthal, Kristian AU - Kuhn, Fabian AU - Scheideler, Christian AU - Schneider, Philipp ID - 15627 SN - 9781611975994 T2 - Proceedings of the Fourteenth Annual ACM-SIAM Symposium on Discrete Algorithms TI - Shortest Paths in a Hybrid Network Model ER - TY - GEN ED - Scheideler, Christian ED - Berenbrink, Petra ID - 14829 SN - 978-1-4503-6184-2 TI - The 31st ACM Symposium on Parallelism in Algorithms and Architectures, SPAA 2019, Phoenix, AZ, USA, June 22-24, 2019 ER - TY - JOUR AU - Feldkord, Björn AU - Meyer auf der Heide, Friedhelm ID - 13873 IS - 3 JF - ACM Transactions on Parallel Computing (TOPC) TI - The Mobile Server Problem VL - 6 ER - TY - CONF AU - Markarian, Christine AU - Meyer auf der Heide, Friedhelm ID - 13942 T2 - Proceedings of the 8th International Conference on Operations Research and Enterprise Systems TI - Online Algorithms for Leasing Vertex Cover and Leasing Non-metric Facility Location ER - TY - JOUR AU - Abu-Khzam, Faisal N. AU - Li, Shouwei AU - Markarian, Christine AU - Meyer auf der Heide, Friedhelm AU - Podlipyan, Pavel ID - 13946 JF - Theoretical Computer Science TI - Efficient parallel algorithms for parameterized problems VL - 786 ER - TY - CONF AU - Castenow, Jannik AU - Kolb, Christina AU - Scheideler, Christian ID - 14539 T2 - Proceedings of the 26th International Colloquium on Structural Information and Communication Complexity (SIROCCO) TI - A Bounding Box Overlay for Competitive Routing in Hybrid Communication Networks ER - TY - CONF AB - We consider congestion control in peer-to-peer distributed systems. The problem can be reduced to the following scenario: Consider a set $V$ of $n$ peers (called \emph{clients} in this paper) that want to send messages to a fixed common peer (called \emph{server} in this paper). We assume that each client $v \in V$ sends a message with probability $p(v) \in [0,1)$ and the server has a capacity of $\sigma \in \mathbb{N}$, i.e., it can recieve at most $\sigma$ messages per round and excess messages are dropped. The server can modify these probabilities when clients send messages. Ideally, we wish to converge to a state with $\sum p(v) = \sigma$ and $p(v) = p(w)$ for all $v,w \in V$. We propose a \emph{loosely} self-stabilizing protocol with a slightly relaxed legitimate state. Our protocol lets the system converge from \emph{any} initial state to a state where $\sum p(v) \in \left[\sigma \pm \epsilon\right]$ and $|p(v)-p(w)| \in O(\frac{1}{n})$. This property is then maintained for $\Omega(n^{\mathfrak{c}})$ rounds in expectation. In particular, the initial client probabilities and server variables are not necessarily well-defined, i.e., they may have arbitrary values. Our protocol uses only $O(W + \log n)$ bits of memory where $W$ is length of node identifiers, making it very lightweight. Finally we state a lower bound on the convergence time an see that our protocol performs asymptotically optimal (up to some polylogarithmic factor). AU - Feldmann, Michael AU - Götte, Thorsten AU - Scheideler, Christian ID - 13182 T2 - Proceedings of the 21st International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS) TI - A Loosely Self-stabilizing Protocol for Randomized Congestion Control with Logarithmic Memory ER - TY - CONF AU - Hinnenthal, Kristian AU - Scheideler, Christian AU - Struijs, Martijn ID - 13652 T2 - 33rd International Symposium on Distributed Computing (DISC 2019) TI - Fast Distributed Algorithms for LP-Type Problems of Low Dimension ER - TY - CONF AB - We study the classic bin packing problem in a fully-dynamic setting, where new items can arrive and old items may depart. We want algorithms with low asymptotic competitive ratio while repacking items sparingly between updates. Formally, each item i has a movement cost c_i >= 0, and we want to use alpha * OPT bins and incur a movement cost gamma * c_i, either in the worst case, or in an amortized sense, for alpha, gamma as small as possible. We call gamma the recourse of the algorithm. This is motivated by cloud storage applications, where fully-dynamic bin packing models the problem of data backup to minimize the number of disks used, as well as communication incurred in moving file backups between disks. Since the set of files changes over time, we could recompute a solution periodically from scratch, but this would give a high number of disk rewrites, incurring a high energy cost and possible wear and tear of the disks. In this work, we present optimal tradeoffs between number of bins used and number of items repacked, as well as natural extensions of the latter measure. AU - Feldkord, Björn AU - Feldotto, Matthias AU - Gupta, Anupam AU - Guruganesh, Guru AU - Kumar, Amit AU - Riechers, Sören AU - Wajc, David ED - Chatzigiannakis, Ioannis ED - Kaklamanis, Christos ED - Marx, Dániel ED - Sannella, Donald ID - 2484 SN - 1868-8969 T2 - 45th International Colloquium on Automata, Languages, and Programming (ICALP 2018) TI - Fully-Dynamic Bin Packing with Little Repacking VL - 107 ER - TY - CONF AU - Feldkord, Björn AU - Meyer auf der Heide, Friedhelm ID - 2485 T2 - Proceedings of the 30th ACM Symposium on Parallelism in Algorithms and Architectures (SPAA) TI - Online Facility Location with Mobile Facilities ER - TY - JOUR AU - Abu-Khzam, Faisal N. AU - Markarian, Christine AU - Meyer auf der Heide, Friedhelm AU - Schubert, Michael ID - 2849 JF - Theory of Computing Systems TI - Approximation and Heuristic Algorithms for Computing Backbones in Asymmetric Ad-hoc Networks ER - TY - CONF AU - Hamann, Heiko AU - Markarian, Christine AU - Meyer auf der Heide, Friedhelm AU - Wahby, Mostafa ID - 2850 T2 - Ninth International Conference on Fun with Algorithms (FUN) TI - Pick, Pack, & Survive: Charging Robots in a Modern Warehouse based on Online Connected Dominating Sets ER - TY - CONF AB - In this paper we present two major results: First, we introduce the first self-stabilizing version of a supervised overlay network (as introduced in~\cite{DBLP:conf/ispan/KothapalliS05}) by presenting a self-stabilizing supervised skip ring. Secondly, we show how to use the self-stabilizing supervised skip ring to construct an efficient self-stabilizing publish-subscribe system. That is, in addition to stabilizing the overlay network, every subscriber of a topic will eventually know all of the publications that have been issued so far for that topic. The communication work needed to processes a subscribe or unsubscribe operation is just a constant in a legitimate state, and the communication work of checking whether the system is still in a legitimate state is just a constant on expectation for the supervisor as well as any process in the system. AU - Feldmann, Michael AU - Kolb, Christina AU - Scheideler, Christian AU - Strothmann, Thim Frederik ID - 1163 KW - Topological Self-stabilization KW - Supervised Overlay KW - Publish-Subscribe System T2 - Proceedings of the 32nd IEEE International Parallel & Distributed Processing Symposium (IPDPS) TI - Self-Stabilizing Supervised Publish-Subscribe Systems ER - TY - CONF AB - We propose a distributed protocol for a queue, called Skueue, which spreads its data fairly onto multiple processes, avoiding bottlenecks in high throughput scenarios. Skueuecan be used in highly dynamic environments, through the addition of join and leave requests to the standard queue operations enqueue and dequeue. Furthermore Skueue satisfies sequential consistency in the asynchronous message passing model. Scalability is achieved by aggregating multiple requests to a batch, which can then be processed in a distributed fashion without hurting the queue semantics. Operations in Skueue need a logarithmic number of rounds w.h.p. until they are processed, even under a high rate of incoming requests. AU - Feldmann, Michael AU - Scheideler, Christian AU - Setzer, Alexander ID - 1164 T2 - Proceedings of the 32nd IEEE International Parallel & Distributed Processing Symposium (IPDPS) TI - Skueue: A Scalable and Sequentially Consistent Distributed Queue ER - TY - JOUR AU - Scheideler, Christian ID - 5984 JF - Theor. Comput. Sci. TI - Preface VL - 751 ER - TY - CONF AB - While a lot of research in distributed computing has covered solutions for self-stabilizing computing and topologies, there is far less work on self-stabilization for distributed data structures. Considering crashing peers in peer-to-peer networks, it should not be taken for granted that a distributed data structure remains intact. In this work, we present a self-stabilizing protocol for a distributed data structure called the hashed Patricia Trie (Kniesburges and Scheideler WALCOM'11) that enables efficient prefix search on a set of keys. The data structure has a wide area of applications including string matching problems while offering low overhead and efficient operations when embedded on top of a distributed hash table. Especially, longest prefix matching for $x$ can be done in $\mathcal{O}(\log |x|)$ hash table read accesses. We show how to maintain the structure in a self-stabilizing way. Our protocol assures low overhead in a legal state and a total (asymptotically optimal) memory demand of $\Theta(d)$ bits, where $d$ is the number of bits needed for storing all keys. AU - Knollmann, Till AU - Scheideler, Christian ED - Izumi, Taisuke ED - Kuznetsov, Petr ID - 4411 KW - Self-Stabilizing KW - Prefix Search KW - Distributed Data Structure T2 - Proceedings of the 20th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS) TI - A Self-Stabilizing Hashed Patricia Trie VL - 11201 ER - TY - CONF AB - Routing is a challenging problem for wireless ad hoc networks, especially when the nodes are mobile and spread so widely that in most cases multiple hops are needed to route a message from one node to another. In fact, it is known that any online routing protocol has a poor performance in the worst case, in a sense that there is a distribution of nodes resulting in bad routing paths for that protocol, even if the nodes know their geographic positions and the geographic position of the destination of a message is known. The reason for that is that radio holes in the ad hoc network may require messages to take long detours in order to get to a destination, which are hard to find in an online fashion. In this paper, we assume that the wireless ad hoc network can make limited use of long-range links provided by a global communication infrastructure like a cellular infrastructure or a satellite in order to compute an abstraction of the wireless ad hoc network that allows the messages to be sent along near-shortest paths in the ad hoc network. We present distributed algorithms that compute an abstraction of the ad hoc network in $\mathcal{O}\left(\log ^2 n\right)$ time using long-range links, which results in $c$-competitive routing paths between any two nodes of the ad hoc network for some constant $c$ if the convex hulls of the radio holes do not intersect. We also show that the storage needed for the abstraction just depends on the number and size of the radio holes in the wireless ad hoc network and is independent on the total number of nodes, and this information just has to be known to a few nodes for the routing to work. AU - Jung, Daniel AU - Kolb, Christina AU - Scheideler, Christian AU - Sundermeier, Jannik ID - 4563 KW - greedy routing KW - ad hoc networks KW - convex hulls KW - c-competitiveness T2 - Proceedings of the 14th International Symposium on Algorithms and Experiments for Wireless Networks (ALGOSENSORS) TI - Competitive Routing in Hybrid Communication Networks ER - TY - CONF AU - Jung, Daniel AU - Kolb, Christina AU - Scheideler, Christian AU - Sundermeier, Jannik ID - 4565 SN - 9781450357999 T2 - Proceedings of the 30th on Symposium on Parallelism in Algorithms and Architectures (SPAA) TI - Brief Announcement: Competitive Routing in Hybrid Communication Networks ER - TY - CONF AU - Meyer auf der Heide, Friedhelm AU - Schaefer, Johannes Sebastian ID - 7570 SN - 9781450357999 T2 - Proceedings of the 30th on Symposium on Parallelism in Algorithms and Architectures - SPAA '18 TI - Brief Announcement: Communication in Systems of Home Based Mobile Agents ER - TY - CONF AB - We extend the concept of monotonic searchability~\cite{DBLP:conf/opodis/ScheidelerSS15}~\cite{DBLP:conf/wdag/ScheidelerSS16} for self-stabilizing systems from one to multiple dimensions. A system is self-stabilizing if it can recover to a legitimate state from any initial illegal state. These kind of systems are most often used in distributed applications. Monotonic searchability provides guarantees when searching for nodes while the recovery process is going on. More precisely, if a search request started at some node $u$ succeeds in reaching its destination $v$, then all future search requests from $u$ to $v$ succeed as well. Although there already exists a self-stabilizing protocol for a two-dimensional topology~\cite{DBLP:journals/tcs/JacobRSS12} and an universal approach for monotonic searchability~\cite{DBLP:conf/wdag/ScheidelerSS16}, it is not clear how both of these concepts fit together effectively. The latter concept even comes with some restrictive assumptions on messages, which is not the case for our protocol. We propose a simple novel protocol for a self-stabilizing two-dimensional quadtree that satisfies monotonic searchability. Our protocol can easily be extended to higher dimensions and offers routing in $\mathcal O(\log n)$ hops for any search request. AU - Feldmann, Michael AU - Kolb, Christina AU - Scheideler, Christian ID - 4351 T2 - Proceedings of the 20th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS) TI - Self-stabilizing Overlays for high-dimensional Monotonic Searchability VL - 11201 ER - TY - CONF AB - We present a peer-to-peer network that supports the efficient processing of orthogonal range queries $R=\bigtimes_{i=1}^{d}[a_i,\,b_i]$ in a $d$-dimensional point space.\\ The network is the same for each dimension, namely a distance halving network like the one introduced by Naor and Wieder (ACM TALG'07). We show how to execute such range queries using $\mathcal{O}\left(2^{d'}d\,\log m + d\,|R|\right)$ hops (and the same number of messages) in total. Here $[m]^d$ is the ground set, $|R|$ is the size and $d'$ the dimension of the queried range. Furthermore, if the peers form a distributed network, the query can be answered in $\mathcal{O}\left(d\,\log m + d\,\sum_{i=1}^{d}(b_i-a_i+1)\right)$ communication rounds. Our algorithms are based on a mapping of the Hilbert Curve through $[m]^d$ to the peers. AU - Benter, Markus AU - Knollmann, Till AU - Meyer auf der Heide, Friedhelm AU - Setzer, Alexander AU - Sundermeier, Jannik ID - 4375 KW - Distributed Storage KW - Multi-Dimensional Range Queries KW - Peer-to-Peer KW - Hilbert Curve T2 - Proceedings of the 4th International Symposium on Algorithmic Aspects of Cloud Computing (ALGOCLOUD) TI - A Peer-to-Peer based Cloud Storage supporting orthogonal Range Queries of arbitrary Dimension ER -