@inproceedings{15169, author = {{Castenow, Jannik and Kolb, Christina and Scheideler, Christian}}, booktitle = {{Proceedings of the 21st International Conference on Distributed Computing and Networking (ICDCN)}}, location = {{Kolkata, Indien}}, publisher = {{ACM}}, title = {{{A Bounding Box Overlay for Competitive Routing in Hybrid Communication Networks}}}, year = {{2020}}, } @misc{17809, author = {{N., N.}}, title = {{{Scalable Multi Objective Path Optimization for Multi-Laser Selective Laser Melting Scanning Systems}}}, year = {{2019}}, } @inproceedings{8534, abstract = {{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.}}, author = {{Feldmann, Michael and Scheideler, Christian}}, booktitle = {{Proceedings of the 31st ACM Symposium on Parallelism in Algorithms and Architectures (SPAA)}}, pages = {{287----296}}, publisher = {{ACM}}, title = {{{Skeap & Seap: Scalable Distributed Priority Queues for Constant and Arbitrary Priorities}}}, doi = {{10.1145/3323165.3323193}}, year = {{2019}}, } @inproceedings{8871, author = {{Augustine, John and Ghaffari, Mohsen and Gmyr, Robert and Hinnenthal, Kristian and Kuhn, Fabian and Li, Jason and Scheideler, Christian}}, booktitle = {{Proceedings of the 31st ACM Symposium on Parallelism in Algorithms and Architectures}}, pages = {{69----79}}, publisher = {{ACM}}, title = {{{Distributed Computation in Node-Capacitated Networks}}}, doi = {{10.1145/3323165.3323195}}, year = {{2019}}, } @inproceedings{6976, abstract = {{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.}}, author = {{Götte, Thorsten and Vijayalakshmi, Vipin Ravindran and Scheideler, Christian}}, booktitle = {{Proceedings of the 2019 IEEE 33rd International Parallel and Distributed Processing Symposium (IPDPS '19)}}, location = {{Rio de Janeiro, Brazil}}, publisher = {{IEEE}}, title = {{{Always be Two Steps Ahead of Your Enemy - Maintaining a Routable Overlay under Massive Churn with an Almost Up-to-date Adversary}}}, year = {{2019}}, } @inproceedings{10586, abstract = {{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.}}, author = {{Scheideler, Christian and Setzer, Alexander}}, booktitle = {{Proceedings of the 46th International Colloquium on Automata, Languages, and Programming}}, keywords = {{Graphs transformations, NP-hardness, approximation algorithms}}, location = {{Patras, Greece}}, pages = {{150:1----150:14}}, publisher = {{Dagstuhl Publishing}}, title = {{{On the Complexity of Local Graph Transformations}}}, doi = {{10.4230/LIPICS.ICALP.2019.150}}, volume = {{132}}, year = {{2019}}, } @proceedings{14829, editor = {{Scheideler, Christian and Berenbrink, Petra}}, isbn = {{978-1-4503-6184-2}}, publisher = {{ACM}}, title = {{{The 31st ACM Symposium on Parallelism in Algorithms and Architectures, SPAA 2019, Phoenix, AZ, USA, June 22-24, 2019}}}, doi = {{10.1145/3323165}}, year = {{2019}}, } @article{14830, author = {{Gmyr, Robert and Lefevre, Jonas and Scheideler, Christian}}, journal = {{Theory Comput. Syst.}}, number = {{2}}, pages = {{177--199}}, title = {{{Self-Stabilizing Metric Graphs}}}, doi = {{10.1007/s00224-017-9823-4}}, volume = {{63}}, year = {{2019}}, } @inproceedings{14539, author = {{Castenow, Jannik and Kolb, Christina and Scheideler, Christian}}, booktitle = {{Proceedings of the 26th International Colloquium on Structural Information and Communication Complexity (SIROCCO)}}, location = {{L'Aquila, Italy}}, pages = {{345--348}}, title = {{{A Bounding Box Overlay for Competitive Routing in Hybrid Communication Networks}}}, doi = {{10.1007/978-3-030-24922-9\_26}}, year = {{2019}}, } @inproceedings{13182, abstract = {{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). }}, author = {{Feldmann, Michael and Götte, Thorsten and Scheideler, Christian}}, booktitle = {{Proceedings of the 21st International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS)}}, pages = {{149--164}}, publisher = {{Springer, Cham}}, title = {{{A Loosely Self-stabilizing Protocol for Randomized Congestion Control with Logarithmic Memory}}}, doi = {{https://doi.org/10.1007/978-3-030-34992-9_13}}, year = {{2019}}, } @misc{10271, author = {{N., N.}}, publisher = {{Universität Paderborn}}, title = {{{Implementation and Evaluation of Authenticated Data Structures Using Intel SGX Enclaves}}}, year = {{2019}}, } @inproceedings{13652, author = {{Hinnenthal, Kristian and Scheideler, Christian and Struijs, Martijn}}, booktitle = {{33rd International Symposium on Distributed Computing (DISC 2019)}}, title = {{{Fast Distributed Algorithms for LP-Type Problems of Low Dimension}}}, doi = {{10.4230/LIPICS.DISC.2019.23}}, year = {{2019}}, } @inproceedings{3422, abstract = {{We study the consensus problem in a synchronous distributed system of n nodes under an adaptive adversary that has a slightly outdated view of the system and can block all incoming and outgoing communication of a constant fraction of the nodes in each round. Motivated by a result of Ben-Or and Bar-Joseph (1998), showing that any consensus algorithm that is resilient against a linear number of crash faults requires $\tilde \Omega(\sqrt n)$ rounds in an n-node network against an adaptive adversary, we consider a late adaptive adversary, who has full knowledge of the network state at the beginning of the previous round and unlimited computational power, but is oblivious to the current state of the nodes. Our main contributions are randomized distributed algorithms that achieve consensus with high probability among all except a small constant fraction of the nodes (i.e., "almost-everywhere'') against a late adaptive adversary who can block up to ε n$ nodes in each round, for a small constant ε >0$. Our first protocol achieves binary almost-everywhere consensus and also guarantees a decision on the majority input value, thus ensuring plurality consensus. We also present an algorithm that achieves the same time complexity for multi-value consensus. Both of our algorithms succeed in $O(log n)$ rounds with high probability, thus showing an exponential gap to the $\tilde\Omega(\sqrt n)$ lower bound of Ben-Or and Bar-Joseph for strongly adaptive crash-failure adversaries, which can be strengthened to $\Omega(n)$ when allowing the adversary to block nodes instead of permanently crashing them. Our algorithms are scalable to large systems as each node contacts only an (amortized) constant number of peers in each communication round. We show that our algorithms are optimal up to constant (resp.\ sub-logarithmic) factors by proving that every almost-everywhere consensus protocol takes $\Omega(log_d n)$ rounds in the worst case, where d is an upper bound on the number of communication requests initiated per node in each round. We complement our theoretical results with an experimental evaluation of the binary almost-everywhere consensus protocol revealing a short convergence time even against an adversary blocking a large fraction of nodes.}}, author = {{Robinson, Peter and Scheideler, Christian and Setzer, Alexander}}, booktitle = {{Proceedings of the 30th ACM Symposium on Parallelism in Algorithms and Architectures (SPAA)}}, isbn = {{978-1-4503-5799-9/18/07}}, keywords = {{distributed consensus, randomized algorithm, adaptive adversary, complexity lower bound}}, location = {{Wien}}, title = {{{Breaking the $\tilde\Omega(\sqrt{n})$ Barrier: Fast Consensus under a Late Adversary}}}, doi = {{10.1145/3210377.3210399}}, year = {{2018}}, } @proceedings{3874, editor = {{Scheideler, Christian and Fineman, Jeremy T.}}, isbn = {{978-1-4503-5799-9}}, location = {{Vienna, Austria}}, publisher = {{ACM}}, title = {{{Proceedings of the 30th on Symposium on Parallelism in Algorithms and Architectures}}}, year = {{2018}}, } @phdthesis{1138, author = {{Gmyr, Robert}}, publisher = {{Universität Paderborn}}, title = {{{Distributed Algorithms for Overlay Networks and Programmable Matter}}}, doi = {{10.17619/UNIPB/1-265}}, year = {{2018}}, } @inproceedings{1163, abstract = {{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. }}, author = {{Feldmann, Michael and Kolb, Christina and Scheideler, Christian and Strothmann, Thim Frederik}}, booktitle = {{Proceedings of the 32nd IEEE International Parallel & Distributed Processing Symposium (IPDPS)}}, keywords = {{Topological Self-stabilization, Supervised Overlay, Publish-Subscribe System}}, location = {{Vancouver}}, publisher = {{IEEE}}, title = {{{Self-Stabilizing Supervised Publish-Subscribe Systems}}}, doi = {{10.1109/IPDPS.2018.00114}}, year = {{2018}}, } @inproceedings{1164, abstract = {{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.}}, author = {{Feldmann, Michael and Scheideler, Christian and Setzer, Alexander}}, booktitle = {{Proceedings of the 32nd IEEE International Parallel & Distributed Processing Symposium (IPDPS)}}, location = {{Vancouver}}, publisher = {{IEEE}}, title = {{{Skueue: A Scalable and Sequentially Consistent Distributed Queue}}}, doi = {{10.1109/IPDPS.2018.00113}}, year = {{2018}}, } @article{1796, author = {{J. Daymude, Joshua and Derakhshandeh, Zahra and Gmyr, Robert and Porter, Alexandra and W. Richa, Andrea and Scheideler, Christian and Strothmann, Thim Frederik}}, journal = {{Natural Computing}}, number = {{1}}, pages = {{81----96}}, title = {{{On the runtime of universal coating for programmable matter}}}, doi = {{10.1007/s11047-017-9658-6}}, year = {{2018}}, } @misc{18030, author = {{N., N.}}, publisher = {{Universität Paderborn}}, title = {{{Monotone Suchbarkeit bei den selbststabilisierenden Protokollen Build-List und Build-Multilist mit systemverlassenden Knoten}}}, year = {{2018}}, } @misc{18031, author = {{N., N.}}, title = {{{Gathering Strategien für mobile Roboterschwärme im Gitternetz}}}, year = {{2018}}, }