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 - CHAP AU - Daymude, Joshua J. AU - Hinnenthal, Kristian AU - Richa, Andréa W. AU - Scheideler, Christian ID - 9599 T2 - Distributed Computing by Mobile Entities, Current Research in Moving and Computing. TI - Computing by Programmable Particles ER - TY - CONF AB - We investigate the maintenance of overlay networks under massive churn, i.e. nodes joining and leaving the network. We assume an adversary that may churn a constant fraction $\alpha n$ of nodes over the course of $\mathcal{O}(\log n)$ rounds. In particular, the adversary has an almost up-to-date information of the network topology as it can observe an only slightly outdated topology that is at least $2$ rounds old. Other than that, we only have the provably minimal restriction that new nodes can only join the network via nodes that have taken part in the network for at least one round. Our contributions are as follows: First, we show that it is impossible to maintain a connected topology if adversary has up-to-date information about the nodes' connections. Further, we show that our restriction concerning the join is also necessary. As our main result present an algorithm that constructs a new overlay- completely independent of all previous overlays - every $2$ rounds. Furthermore, each node sends and receives only $\mathcal{O}(\log^3 n)$ messages each round. As part of our solution we propose the Linearized DeBruijn Swarm (LDS), a highly churn resistant overlay, which will be maintained by the algorithm. However, our approaches can be transferred to a variety of classical P2P Topologies where nodes are mapped into the $[0,1)$-interval. AU - Götte, Thorsten AU - Vijayalakshmi, Vipin Ravindran AU - Scheideler, Christian ID - 6976 T2 - Proceedings of the 2019 IEEE 33rd International Parallel and Distributed Processing Symposium (IPDPS '19) TI - Always be Two Steps Ahead of Your Enemy - Maintaining a Routable Overlay under Massive Churn with an Almost Up-to-date Adversary 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 - Götte, Thorsten AU - Hinnenthal, Kristian AU - Scheideler, Christian ID - 12944 T2 - Structural Information and Communication Complexity TI - Faster Construction of Overlay Networks 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 - JOUR AU - Gmyr, Robert AU - Lefevre, Jonas AU - Scheideler, Christian ID - 14830 IS - 2 JF - Theory Comput. Syst. TI - Self-Stabilizing Metric Graphs VL - 63 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 AU - Augustine, John AU - Hinnenthal, Kristian AU - Kuhn, Fabian AU - Scheideler, Christian AU - Schneider, Philipp ED - Chawla, Shuchi ID - 27051 T2 - Proceedings of the 2020 ACM-SIAM Symposium on Discrete Algorithms, SODA 2020, Salt Lake City, UT, USA, January 5-8, 2020 TI - Shortest Paths in a Hybrid Network Model ER - TY - JOUR AU - Gmyr, Robert AU - Hinnenthal, Kristian AU - Kostitsyna, Irina AU - Kuhn, Fabian AU - Rudolph, Dorian AU - Scheideler, Christian AU - Strothmann, Thim ID - 17808 IS - 2 JF - Nat. Comput. TI - Forming tile shapes with simple robots VL - 19 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 AB - We consider the clock synchronization problem in the (discrete) beeping model: Given a network of $n$ nodes with each node having a clock value $\delta(v) \in \{0,\ldots T-1\}$, the goal is to synchronize the clock values of all nodes such that they have the same value in any round. As is standard in clock synchronization, we assume \emph{arbitrary activations} for all nodes, i.e., the nodes start their protocol at an arbitrary round (not limited to $\{0,\ldots,T-1\}$). We give an asymptotically optimal algorithm that runs in $4D + \Bigl\lfloor \frac{D}{\lfloor T/4 \rfloor} \Bigr \rfloor \cdot (T \mod 4) = O(D)$ rounds, where $D$ is the diameter of the network. Once all nodes are in sync, they beep at the same round every $T$ rounds. The algorithm drastically improves on the $O(T D)$-bound of \cite{firefly_sync} (where $T$ is required to be at least $4n$, so the bound is no better than $O(nD)$). Our algorithm is very simple as nodes only have to maintain $3$ bits in addition to the $\lceil \log T \rceil$ bits needed to maintain the clock. Furthermore we investigate the complexity of \emph{self-stabilizing} solutions for the clock synchronization problem: We first show lower bounds of $\Omega(\max\{T,n\})$ rounds on the runtime and $\Omega(\log(\max\{T,n\}))$ bits of memory required for any such protocol. Afterwards we present a protocol that runs in $O(\max\{T,n\})$ rounds using at most $O(\log(\max\{T,n\}))$ bits at each node, which is asymptotically optimal with regards to both, runtime and memory requirements. AU - Feldmann, Michael AU - Khazraei, Ardalan AU - Scheideler, Christian ID - 16903 T2 - Proceedings of the 32nd ACM Symposium on Parallelism in Algorithms and Architectures (SPAA) TI - Time- and Space-Optimal Discrete Clock Synchronization in the Beeping Model 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 - CONF AU - Daymude, Joshua J. AU - Gmyr, Robert AU - Hinnenthal, Kristian AU - Kostitsyna, Irina AU - Scheideler, Christian AU - Richa, Andréa W. ID - 16346 SN - 9781450377515 T2 - Proceedings of the 21st International Conference on Distributed Computing and Networking TI - Convex Hull Formation for Programmable Matter ER - TY - CONF AU - Dolev, Shlomi AU - Prasadh Narayanan, Ram AU - Scheideler, Christian AU - Schindelhauer, Christian ED - Galluccio, Laura ED - Mitra, Urbashi ED - Magarini, Maurizio ED - Abada, Sergi ED - Taynnan Barros, Michael ED - Krishnaswamy, Bhuvana ID - 25105 T2 - NANOCOM '21: The Eighth Annual ACM International Conference on Nanoscale Computing and Communication, Virtual Event, Italy, September 7 - 9, 2021 TI - Logarithmic Time MIMO Based Self-Stabilizing Clock Synchronization ER - TY - CONF AU - Feldmann, Michael AU - Padalkin, Andreas AU - Scheideler, Christian AU - Dolev, Shlomi ED - Johnen, Colette ED - Michael Schiller, Elad ED - Schmid, Stefan ID - 28917 T2 - Stabilization, Safety, and Security of Distributed Systems - 23rd International Symposium, (SSS) 2021, Virtual Event, November 17-20, 2021, Proceedings TI - Coordinating Amoebots via Reconfigurable Circuits VL - 13046 ER - TY - CONF AU - Dolev, Shlomi AU - Prasadh Narayanan, Ram AU - Scheideler, Christian AU - Schindelhauer, Christian ED - Galluccio, Laura ED - Mitra, Urbashi ED - Magarini, Maurizio ED - Abada, Sergi ED - Taynnan Barros, Michael ED - Krishnaswamy, Bhuvana ID - 27048 T2 - NANOCOM '21: The Eighth Annual ACM International Conference on Nanoscale Computing and Communication, Virtual Event, Italy, September 7 - 9, 2021 TI - Logarithmic Time MIMO Based Self-Stabilizing Clock Synchronization ER - TY - CONF AU - J. Daymude, Joshua AU - W. Richa, Andrea AU - Scheideler, Christian ED - Gilbert, Seth ID - 27050 T2 - 35th International Symposium on Distributed Computing, DISC 2021, October 4-8, 2021, Freiburg, Germany (Virtual Conference) TI - The Canonical Amoebot Model: Algorithms and Concurrency Control VL - 209 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 - CONF AU - Coy, Sam AU - Czumaj, Artur AU - Feldmann, Michael AU - Hinnenthal, Kristian AU - Kuhn, Fabian AU - Scheideler, Christian AU - Schneider, Philipp AU - Struijs, Martijn ED - Bramas, Quentin ED - Gramoli, Vincent ED - Milani, Alessia ID - 30217 T2 - 25th International Conference on Principles of Distributed Systems, OPODIS 2021, December 13-15, 2021, Strasbourg, France TI - Near-Shortest Path Routing in Hybrid Communication Networks VL - 217 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 - JOUR AU - Feldmann, Michael AU - Padalkin, Andreas AU - Scheideler, Christian AU - Dolev, Shlomi ID - 31060 IS - 4 JF - J. Comput. Biol. TI - Coordinating Amoebots via Reconfigurable Circuits VL - 29 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 - CONF AU - Kostitsyna, Irina AU - Scheideler, Christian AU - Warner, Daniel ED - Ouldridge, Thomas E. ED - Wickham, Shelley F. J. ID - 32603 SN - 1868-8969 T2 - 28th International Conference on DNA Computing and Molecular Programming (DNA 28) TI - Fault-Tolerant Shape Formation in the Amoebot Model VL - 238 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 - Götte, Thorsten AU - Scheideler, Christian ED - Agrawal, Kunal ED - Lee, I-Ting Angelina ID - 33240 T2 - SPAA ’22: 34th ACM Symposium on Parallelism in Algorithms and Architectures, Philadelphia, PA, USA, July 11 - 14, 2022 TI - Brief Announcement: The (Limited) Power of Multiple Identities: Asynchronous Byzantine Reliable Broadcast with Improved Resilience through Collusion ER - TY - CONF AU - Kostitsyna, Irina AU - Scheideler, Christian AU - Warner, Daniel ED - Aspnes, James ED - Michail, Othon ID - 30987 SN - 1868-8969 T2 - 1st Symposium on Algorithmic Foundations of Dynamic Networks (SAND 2022) TI - Brief Announcement: Fault-Tolerant Shape Formation in the Amoebot Model 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 - 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 - 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 - CHAP AU - Blömer, Johannes AU - Eidens, Fabian AU - Jager, Tibor AU - Niehues, David AU - Scheideler, Christian ED - Haake, Claus-Jochen ED - Meyer auf der Heide, Friedhelm ED - Platzner, Marco ED - Wachsmuth, Henning ED - Wehrheim, Heike ID - 45891 T2 - On-The-Fly Computing -- Individualized IT-services in dynamic markets TI - Robustness and Security VL - 412 ER -