@inproceedings{20817, author = {{Bienkowski, Marcin and Feldkord, Björn and Schmidt, Pawel}}, booktitle = {{Proceedings of the 38th Symposium on Theoretical Aspects of Computer Science (STACS)}}, pages = {{14:1 -- 14:17}}, title = {{{A Nearly Optimal Deterministic Online Algorithm for Non-Metric Facility Location}}}, doi = {{10.4230/LIPIcs.STACS.2021.14}}, year = {{2021}}, } @article{22510, abstract = {{Over the past decades, the Gathering problem, which asks to gather a group of robots in finite time given some restrictions, has been intensively studied. In this paper, we are given a group of n autonomous, dimensionless, deterministic, and anonymous robots, with bounded viewing range. Assuming a continuous time model, the goal is to gather these robots into one point in finite time. We introduce a simple convergence criterion that defines a new class of algorithms which perform gathering in O(nd) time, where d is the diameter of the initial robot configuration. We show that some gathering algorithms in the literature belong to this class and propose two new algorithms that belong to this class and have quadratic running time, namely, Go-To-The-Relative-Center algorithm (GTRC) and Safe-Go-To-The-Relative-Center algorithm (S-GTRC). We prove that the latter can perform gathering without collision by using a slightly more complex robot model: non oblivious, chiral, and luminous (i.e. robots have observable external memory, as in [8]). We also consider a variant of the Gathering problem, the Near-Gathering problem, in which robots must get close to each other without colliding. We show that S-GTRC solves the Near-Gathering problem in quadratic time and assumes a weaker robot model than the one assumed in the current state-of-the-art.}}, author = {{Li, Shouwei and Markarian, Christine and Meyer auf der Heide, Friedhelm and Podlipyan, Pavel}}, issn = {{0304-3975}}, journal = {{Theoretical Computer Science}}, keywords = {{Local algorithms, Distributed algorithms, Collisionless gathering, Mobile robots, Multiagent system}}, pages = {{41--60}}, title = {{{A continuous strategy for collisionless gathering}}}, doi = {{10.1016/j.tcs.2020.10.037}}, volume = {{852}}, year = {{2021}}, } @article{22511, abstract = {{In this paper, we reconsider the well-known discrete, round-based Go-To-The-Center algorithm due to Ando, Suzuki, and Yamashita [2] for gathering n autonomous mobile robots with limited viewing range in the plane. Remarquably, this algorithm exploits the fact that during its execution, many collisions of robots occur. Such collisions are interpreted as a success because it is assumed that such collided robots behave the same from now on. This is acceptable under the assumption that each robot is represented by a single point. Otherwise, collisions should be avoided. In this paper, we consider a continuous Go-To-The-Center algorithm in which the robots continuously observe the positions of their neighbors and adapt their speed (assuming a speed limit) and direction. Our first results are time bounds of O(n2) for gathering in two dimensions Euclidean space, and Θ(n) for the one dimension. Our main contribution is the introduction and evaluation of a continuous algorithm which performs Go-To-The-Center considering only the neighbors of a robot with respect to the Gabriel subgraph of the visibility graph, i.e. Go-To-The-Gabriel-Center algorithm. We show that this modification still correctly executes gathering in one and two dimensions, with the same time bounds as above. Simulations exhibit a severe difference of the behavior of the Go-To-The-Center and the Go-To-The-Gabriel-Center algorithms: Whereas lots of collisions occur during a run of the Go-To-The-Center algorithm, typically only one, namely the final collision occurs during a run of the Go-To-The-Gabriel-Center algorithm. We can prove this “collisionless property” of the Go-To-The-Gabriel-Center algorithm for one dimension. In two-dimensional Euclidean space, we conjecture that the “collisionless property” holds for almost every initial configuration. We support our conjecture with measurements obtained from the simulation where robots execute both continuous Go-To-The-Center and Go-To-The-Gabriel-Center algorithms. }}, author = {{Li, Shouwei and Meyer auf der Heide, Friedhelm and Podlipyan, Pavel}}, issn = {{0304-3975}}, journal = {{Theoretical Computer Science}}, keywords = {{Local algorithms, Distributed algorithms, Collisionless gathering, Mobile robots, Multiagent system}}, pages = {{29--40}}, title = {{{The impact of the Gabriel subgraph of the visibility graph on the gathering of mobile autonomous robots}}}, doi = {{10.1016/j.tcs.2020.11.009}}, volume = {{852}}, year = {{2021}}, } @inproceedings{26986, author = {{Castenow, Jannik and Götte, Thorsten and Knollmann, Till and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedings of the 23rd International Symposium on Stabilization, Safety, and Security of Distributed Systems, SSS 2021}}, editor = {{Johnen, C. and Schiller, E.M. and Schmid, S.}}, location = {{Online}}, pages = {{289--304 }}, publisher = {{Springer}}, title = {{{The Max-Line-Formation Problem – And New Insights for Gathering and Chain-Formation}}}, doi = {{10.1007/978-3-030-91081-5_19}}, volume = {{13046}}, year = {{2021}}, } @unpublished{27778, abstract = {{Consider a set of jobs connected to a directed acyclic task graph with a fixed source and sink. The edges of this graph model precedence constraints and the jobs have to be scheduled with respect to those. We introduce the Server Cloud Scheduling problem, in which the jobs have to be processed either on a single local machine or on one of many cloud machines. Both the source and the sink have to be scheduled on the local machine. For each job, processing times both on the server and in the cloud are given. Furthermore, for each edge in the task graph, a communication delay is included in the input and has to be taken into account if one of the two jobs is scheduled on the server, the other in the cloud. The server can process jobs sequentially, whereas the cloud can serve as many as needed in parallel, but induces costs. We consider both makespan and cost minimization. The main results are an FPTAS with respect for the makespan objective for a fairly general case and strong hardness for the case with unit processing times and delays.}}, author = {{Maack, Marten and Meyer auf der Heide, Friedhelm and Pukrop, Simon}}, booktitle = {{arXiv:2108.02109}}, title = {{{Full Version -- Server Cloud Scheduling}}}, year = {{2021}}, } @misc{44234, author = {{Berger, Thilo Frederik}}, title = {{{Combining Mobility, Heterogeneity, and Leasing Approaches for Online Resource Allocation}}}, year = {{2021}}, } @misc{44233, author = {{Pranger, Sebastian}}, title = {{{Online k-Facility Reallocation using k-Server Algorithms}}}, year = {{2021}}, } @inproceedings{19899, abstract = {{Most existing robot formation problems seek a target formation of a certain minimal and, thus, efficient structure. Examples include the Gathering and the Chain-Formation problem. In this work, we study formation problems that try to reach a maximal structure, supporting for example an efficient coverage in exploration scenarios. A recent example is the NASA Shapeshifter project, which describes how the robots form a relay chain along which gathered data from extraterrestrial cave explorations may be sent to a home base. As a first step towards understanding such maximization tasks, we introduce and study the Max-Chain-Formation problem, where $n$ robots are ordered along a winding, potentially self-intersecting chain and must form a connected, straight line of maximal length connecting its two endpoints. We propose and analyze strategies in a discrete and in a continuous time model. In the discrete case, we give a complete analysis if all robots are initially collinear, showing that the worst-case time to reach an $\varepsilon$-approximation is upper bounded by $\mathcal{O}(n^2 \cdot \log (n/\varepsilon))$ and lower bounded by $\Omega(n^2 \cdot~\log (1/\varepsilon))$. If one endpoint of the chain remains stationary, this result can be extended to the non-collinear case. If both endpoints move, we identify a family of instances whose runtime is unbounded. For the continuous model, we give a strategy with an optimal runtime bound of $\Theta(n)$. Avoiding an unbounded runtime similar to the discrete case relies crucially on a counter-intuitive aspect of the strategy: slowing down the endpoints while all other robots move at full speed. Surprisingly, we can show that a similar trick does not work in the discrete model.}}, author = {{Castenow, Jannik and Kling, Peter and Knollmann, Till and Meyer auf der Heide, Friedhelm}}, booktitle = {{Stabilization, Safety, and Security of Distributed Systems - 22nd International Symposium, SSS 2020, Austin, Texas, USA, November 18-21, 2020, Proceedings}}, editor = {{Devismes , Stéphane and Mittal, Neeraj }}, isbn = {{978-3-030-64347-8}}, pages = {{65--80}}, publisher = {{Springer}}, title = {{{A Discrete and Continuous Study of the Max-Chain-Formation Problem – Slow Down to Speed Up}}}, doi = {{10.1007/978-3-030-64348-5_6}}, volume = {{12514}}, year = {{2020}}, } @inproceedings{20159, abstract = {{Let G = (V,E) be an undirected graph on n vertices with non-negative capacities on its edges. The mincut sensitivity problem for the insertion of an edge is defined as follows. Build a compact data structure for G and a given set S ⊆ V of vertices that, on receiving any edge (x,y) ∈ S×S of positive capacity as query input, can efficiently report the set of all pairs from S× S whose mincut value increases upon insertion of the edge (x,y) to G. The only result that exists for this problem is for a single pair of vertices (Picard and Queyranne, Mathematical Programming Study, 13 (1980), 8-16). We present the following results for the single source and the all-pairs versions of this problem. 1) Single source: Given any designated source vertex s, there exists a data structure of size 𝒪(|S|) that can output all those vertices from S whose mincut value to s increases upon insertion of any given edge. The time taken by the data structure to answer any query is 𝒪(|S|). 2) All-pairs: There exists an 𝒪(|S|²) size data structure that can output all those pairs of vertices from S× S whose mincut value gets increased upon insertion of any given edge. The time taken by the data structure to answer any query is 𝒪(k), where k is the number of pairs of vertices whose mincut increases. For both these versions, we also address the problem of reporting the values of the mincuts upon insertion of any given edge. To derive our results, we use interesting insights into the nearest and the farthest mincuts for a pair of vertices. In addition, a crucial result, that we establish and use in our data structures, is that there exists a directed acyclic graph of 𝒪(n) size that compactly stores the farthest mincuts from all vertices of V to a designated vertex s in the graph. We believe that this result is of independent interest, especially, because it also complements a previously existing result by Hariharan et al. (STOC 2007) that the nearest mincuts from all vertices of V to s is a laminar family, and hence, can be stored compactly in a tree of 𝒪(n) size.}}, author = {{Baswana, Surender and Gupta, Shiv and Knollmann, Till}}, booktitle = {{28th Annual European Symposium on Algorithms (ESA 2020)}}, editor = {{Grandoni, Fabrizio and Herman, Grzegorz and Sanders, Peter}}, isbn = {{978-3-95977-162-7}}, issn = {{1868-8969}}, keywords = {{Mincut, Sensitivity, Data Structure}}, pages = {{12:1--12:14}}, publisher = {{Schloss Dagstuhl -- Leibniz-Zentrum für Informatik}}, title = {{{Mincut Sensitivity Data Structures for the Insertion of an Edge}}}, doi = {{10.4230/LIPIcs.ESA.2020.12}}, volume = {{173}}, year = {{2020}}, } @inproceedings{20185, author = {{Castenow, Jannik and Harbig, Jonas and Jung, Daniel and Knollmann, Till and Meyer auf der Heide, Friedhelm}}, booktitle = {{Stabilization, Safety, and Security of Distributed Systems - 22nd International Symposium, SSS 2020, Austin, Texas, USA, November 18-21, 2020, Proceedings }}, editor = {{Devismes, Stéphane and Mittal, Neeraj}}, isbn = {{978-3-030-64347-8}}, pages = {{60--64}}, publisher = {{Springer}}, title = {{{Brief Announcement: Gathering in Linear Time: A Closed Chain of Disoriented & Luminous Robots with Limited Visibility }}}, doi = {{10.1007/978-3-030-64348-5_5}}, volume = {{12514}}, year = {{2020}}, } @inproceedings{17370, abstract = {{ 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.}}, author = {{Castenow, Jannik and Feldkord, Björn and Knollmann, Till and Malatyali, Manuel and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedings of the 32nd ACM Symposium on Parallelism in Algorithms and Architectures}}, isbn = {{9781450369350}}, keywords = {{Online Multi-Commodity Facility Location, Competitive Ratio, Online Optimization, Facility Location Problem}}, title = {{{The Online Multi-Commodity Facility Location Problem}}}, doi = {{10.1145/3350755.3400281}}, year = {{2020}}, } @inproceedings{17371, author = {{Castenow, Jannik and Kling, Peter and Knollmann, Till and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedings of the 32nd ACM Symposium on Parallelism in Algorithms and Architectures}}, isbn = {{9781450369350}}, title = {{{Brief Announcement: A Discrete and Continuous Study of the Max-Chain-Formation Problem: Slow Down to Speed up}}}, doi = {{10.1145/3350755.3400263}}, year = {{2020}}, } @inproceedings{16968, abstract = {{In this work, we initiate the research about the Gathering problem for robots with limited viewing range in the three-dimensional Euclidean space. In the Gathering problem, a set of initially scattered robots is required to gather at the same position. The robots' capabilities are very restricted -- they do not agree on any coordinate system or compass, have a limited viewing range, have no memory of the past and cannot communicate. We study the problem in two different time models, in FSYNC (fully synchronized discrete rounds) and the continuous time model. For FSYNC, we introduce the 3D-Go-To-The-Center-strategy and prove a runtime of $\Theta(n^2)$ that matches the currently best runtime bound for the same model in the Euclidean plane [SPAA'11]. Our main result is the generalization of contracting strategies (continuous time) from [Algosensors'17] to three dimensions. In contracting strategies, every robot that is located on the global convex hull of all robots' positions moves with full speed towards the inside of the convex hull. We prove a runtime bound of $O(\Delta \cdot n^{3/2})$ for any three-dimensional contracting strategy, where $\Delta$ denotes the diameter of the initial configuration. This comes up to a factor of $\sqrt{n}$ close to the lower bound of $\Omega (\Delta \cdot n)$ which is already true in two dimensions. In general, it might be hard for robots with limited viewing range to decide whether they are located on the global convex hull and which movement maintains the connectivity of the swarm, rendering the design of concrete contracting strategies a challenging task. We prove that the continuous variant of 3D-Go-To-The-Center is contracting and keeps the swarm connected. Moreover, we give a simple design criterion for three-dimensional contracting strategies that maintains the connectivity of the swarm and introduce an exemplary strategy based on this criterion.}}, author = {{Braun, Michael and Castenow, Jannik and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedings of the 27th Conference on Structural Information and Communication Complexity (SIROCCO)}}, location = {{Paderborn}}, publisher = {{Springer}}, title = {{{Local Gathering of Mobile Robots in Three Dimensions}}}, doi = {{10.1007/978-3-030-54921-3_4}}, year = {{2020}}, } @phdthesis{15631, author = {{Feldkord, Björn}}, title = {{{Mobile Resource Allocation}}}, doi = {{10.17619/UNIPB/1-869}}, year = {{2020}}, } @article{15025, abstract = {{In software engineering, the imprecise requirements of a user are transformed to a formal requirements specification during the requirements elicitation process. This process is usually guided by requirements engineers interviewing the user. We want to partially automate this first step of the software engineering process in order to enable users to specify a desired software system on their own. With our approach, users are only asked to provide exemplary behavioral descriptions. The problem of synthesizing a requirements specification from examples can partially be reduced to the problem of grammatical inference, to which we apply an active coevolutionary learning approach. However, this approach would usually require many feedback queries to be sent to the user. In this work, we extend and generalize our active learning approach to receive knowledge from multiple oracles, also known as proactive learning. The ‘user oracle’ represents input received from the user and the ‘knowledge oracle’ represents available, formalized domain knowledge. We call our two-oracle approach the ‘first apply knowledge then query’ (FAKT/Q) algorithm. We compare FAKT/Q to the active learning approach and provide an extensive benchmark evaluation. As result we find that the number of required user queries is reduced and the inference process is sped up significantly. Finally, with so-called On-The-Fly Markets, we present a motivation and an application of our approach where such knowledge is available.}}, author = {{Wever, Marcel Dominik and van Rooijen, Lorijn and Hamann, Heiko}}, journal = {{Evolutionary Computation}}, number = {{2}}, pages = {{165–193}}, publisher = {{MIT Press Journals}}, title = {{{Multi-Oracle Coevolutionary Learning of Requirements Specifications from Examples in On-The-Fly Markets}}}, doi = {{10.1162/evco_a_00266}}, volume = {{28}}, year = {{2020}}, } @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}}, } @article{16299, author = {{Castenow, Jannik and Fischer, Matthias and Harbig, Jonas and Jung, Daniel and Meyer auf der Heide, Friedhelm}}, issn = {{0304-3975}}, journal = {{Theoretical Computer Science}}, pages = {{289--309}}, title = {{{Gathering Anonymous, Oblivious Robots on a Grid}}}, doi = {{10.1016/j.tcs.2020.02.018}}, volume = {{815}}, year = {{2020}}, } @inproceedings{13868, author = {{Pukrop, Simon and Mäcker, Alexander and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedings of the 46th International Conference on Current Trends in Theory and Practice of Computer Science (SOFSEM)}}, title = {{{Approximating Weighted Completion Time for Order Scheduling with Setup Times}}}, year = {{2020}}, } @article{13770, author = {{Karl, Holger and Kundisch, Dennis and Meyer auf der Heide, Friedhelm and Wehrheim, Heike}}, journal = {{Business & Information Systems Engineering}}, number = {{6}}, pages = {{467--481}}, publisher = {{Springer}}, title = {{{A Case for a New IT Ecosystem: On-The-Fly Computing}}}, doi = {{10.1007/s12599-019-00627-x}}, volume = {{62}}, year = {{2020}}, } @inproceedings{17432, author = {{Baswana, Surender and Gupta, Shiv and Tulsyan, Ayush}}, booktitle = {{44th International Symposium on Mathematical Foundations of Computer Science (MFCS 2019)}}, pages = {{65:1----65:16}}, publisher = {{Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik}}, title = {{{Fault Tolerant and Fully Dynamic DFS in Undirected Graphs: Simple Yet Efficient}}}, doi = {{10.4230/LIPICS.MFCS.2019.65}}, year = {{2019}}, } @inproceedings{17667, abstract = {{Resolving distributed attacks benefits from collaboration between networks. We present three approaches for the same multi-domain defensive action that can be applied in such an alliance: 1) Counteract Everywhere, 2) Minimize Countermeasures, and 3) Minimize Propagation. First, we provide a formula to compute efficiency of a defense; then we use this formula to compute the efficiency of the approaches under various circumstances. Finally, we discuss how task execution order and timing influence defense efficiency. Our results show that the Minimize Propagation approach is the most efficient method when defending against the chosen attack.}}, author = {{Koning, Ralph and Polevoy, Gleb and Meijer, Lydia and de Laat, Cees and Grosso, Paola}}, booktitle = {{2019 6th IEEE International Conference on Cyber Security and Cloud Computing (CSCloud)/ 2019 5th IEEE International Conference on Edge Computing and Scalable Cloud (EdgeCom)}}, issn = {{null}}, keywords = {{computer network security, multinetwork environments, multidomain defensive action, task execution order, timing influence defense efficiency, distributed attacks, collaborative security defence approach, minimize propagation approach, minimize countermeasure approach, counteract everywhere approach, Conferences, Cloud computing, Computer crime, Edge computing, Security, Defense Approaches, Multi-Domain Defense, Collaborative Defense, Defense Algorithms, Computer Networks}}, pages = {{113--123}}, title = {{{Approaches for Collaborative Security Defences in Multi Network Environments}}}, doi = {{10.1109/CSCloud/EdgeCom.2019.000-9}}, year = {{2019}}, } @phdthesis{18975, author = {{Malatyali, Manuel}}, title = {{{Big Data: Sublinear Algorithms for Distributed Data Streams}}}, doi = {{10.17619/UNIPB/1-766}}, year = {{2019}}, } @phdthesis{8080, abstract = {{This thesis investigates approximate pure Nash equilibria in different game-theoretic models. In such an outcome, no player can improve her objective by more than a given factor through a deviation to another strategy. In the first part, we investigate two variants of Congestion Games in which the existence of pure Nash equilibria is guaranteed through a potential function argument. However, the computation of such equilibria might be hard. We construct and analyze approximation algorithms that enable the computation of states with low approximation factors in polynomial time. To show their guarantees we use sub games among players, bound the potential function values of arbitrary states and exploit a connection between Shapley and proportional cost shares. Furthermore, we apply and analyze sampling techniques for the computation of approximate Shapley values in different settings. In the second part, we concentrate on the existence of approximate pure Nash equilibria in games in which no pure Nash equilibria exist in general. In the model of Coevolving Opinion Formation Games, we bound the approximation guarantees for natural states nearly independent of the specific definition of the players' neighborhoods by applying a concept of virtual costs. For the special case of only one influential neighbor, we even show lower approximation factors for a natural strategy. Then, we investigate a two-sided Facility Location Game among facilities and clients on a line with an objective function consisting of distance and load. We show tight bounds on the approximation factor for settings with three facilities and infinitely many clients. For the general scenario with an arbitrary number of facilities, we bound the approximation factor for two promising candidates, namely facilities that are uniformly distributed and which are paired.}}, author = {{Feldotto, Matthias}}, title = {{{Approximate Pure Nash Equilibria in Congestion, Opinion Formation and Facility Location Games}}}, doi = {{10.17619/UNIPB/1-588}}, year = {{2019}}, } @inproceedings{8866, author = {{Jansen, Klaus and Maack, Marten and Mäcker, Alexander}}, booktitle = {{Proceedings of the 33rd IEEE International Parallel and Distributed Processing Symposium (IPDPS)}}, pages = {{145 -- 154}}, publisher = {{IEEE}}, title = {{{Scheduling on (Un-)Related Machines with Setup Times}}}, year = {{2019}}, } @inproceedings{5471, abstract = {{We characterise the set of dominant strategy incentive compatible (DSIC), strongly budget balanced (SBB), and ex-post individually rational (IR) mechanisms for the multi-unit bilateral trade setting. In such a setting there is a single buyer and a single seller who holds a finite number k of identical items. The mechanism has to decide how many units of the item are transferred from the seller to the buyer and how much money is transferred from the buyer to the seller. We consider two classes of valuation functions for the buyer and seller: Valuations that are increasing in the number of units in possession, and the more specific class of valuations that are increasing and submodular. Furthermore, we present some approximation results about the performance of certain such mechanisms, in terms of social welfare: For increasing submodular valuation functions, we show the existence of a deterministic 2-approximation mechanism and a randomised e/(1-e) approximation mechanism, matching the best known bounds for the single-item setting.}}, author = {{Lazos, Philip and Goldberg, Paul and Skopalik, Alexander and Gerstgrasser, Matthias and de Keijzer, Bart}}, booktitle = {{Proceedings of the Thirty-Third AAAI Conference on Artificial Intelligence (AAAI)}}, location = {{Honolulu, Hawaii, USA}}, title = {{{ Multi-unit Bilateral Trade}}}, doi = {{10.1609/aaai.v33i01.33011973}}, year = {{2019}}, } @inproceedings{12870, author = {{Feldkord, Björn and Knollmann, Till and Malatyali, Manuel and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedings of the 17th Workshop on Approximation and Online Algorithms (WAOA)}}, pages = {{120 -- 137}}, publisher = {{Springer}}, title = {{{Managing Multiple Mobile Resources}}}, doi = {{10.1007/978-3-030-39479-0_9}}, year = {{2019}}, } @phdthesis{14851, author = {{Mäcker, Alexander}}, title = {{{On Scheduling with Setup Times}}}, doi = {{10.17619/UNIPB/1-828}}, year = {{2019}}, } @unpublished{16341, abstract = {{We present a technique for rendering highly complex 3D scenes in real-time by generating uniformly distributed points on the scene's visible surfaces. The technique is applicable to a wide range of scene types, like scenes directly based on complex and detailed CAD data consisting of billions of polygons (in contrast to scenes handcrafted solely for visualization). This allows to visualize such scenes smoothly even in VR on a HMD with good image quality, while maintaining the necessary frame-rates. In contrast to other point based rendering methods, we place points in an approximated blue noise distribution only on visible surfaces and store them in a highly GPU efficient data structure, allowing to progressively refine the number of rendered points to maximize the image quality for a given target frame rate. Our evaluation shows that scenes consisting of a high amount of polygons can be rendered with interactive frame rates with good visual quality on standard hardware.}}, author = {{Brandt, Sascha and Jähn, Claudius and Fischer, Matthias and Meyer auf der Heide, Friedhelm}}, booktitle = {{arXiv:1904.08225}}, title = {{{Rendering of Complex Heterogenous Scenes using Progressive Blue Surfels}}}, year = {{2019}}, } @article{13873, author = {{Feldkord, Björn and Meyer auf der Heide, Friedhelm}}, journal = {{ACM Transactions on Parallel Computing (TOPC)}}, number = {{3}}, title = {{{The Mobile Server Problem}}}, doi = {{10.1145/3364204}}, volume = {{6}}, year = {{2019}}, } @article{13937, author = {{Meyer auf der Heide, Friedhelm}}, journal = {{Mathematische Semesterberichte}}, number = {{2}}, pages = {{259--260}}, title = {{{Paul Curzon, Peter W. McOwan: Computational Thinking; Die Welt des algorithmischen Denkens – in Spielen, Zaubertricks und Rätseln}}}, doi = {{10.1007/s00591-019-00249-0}}, volume = {{66}}, year = {{2019}}, } @inbook{13939, author = {{Kling, Peter and Meyer auf der Heide, Friedhelm}}, booktitle = {{Distributed Computing by Mobile Entities, Current Research in Moving and Computing}}, pages = {{317--334}}, publisher = {{Springer}}, title = {{{Continuous Protocols for Swarm Robotics}}}, doi = {{10.1007/978-3-030-11072-7\_13}}, volume = {{11340}}, year = {{2019}}, } @inproceedings{13942, author = {{Markarian, Christine and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedings of the 8th International Conference on Operations Research and Enterprise Systems}}, pages = {{315--321}}, publisher = {{SciTePress}}, title = {{{Online Algorithms for Leasing Vertex Cover and Leasing Non-metric Facility Location}}}, doi = {{10.5220/0007369503150321}}, year = {{2019}}, } @article{13946, author = {{Abu-Khzam, Faisal N. and Li, Shouwei and Markarian, Christine and Meyer auf der Heide, Friedhelm and Podlipyan, Pavel}}, journal = {{Theoretical Computer Science}}, pages = {{2--12}}, title = {{{Efficient parallel algorithms for parameterized problems}}}, doi = {{10.1016/j.tcs.2018.11.006}}, volume = {{786}}, 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{10281, abstract = {{Competing firms tend to select similar locations for their stores. This phenomenon, called the principle of minimum differentiation, was captured by Hotelling with a landmark model of spatial competition but is still the object of an ongoing scientific debate. Although consistently observed in practice, many more realistic variants of Hotelling's model fail to support minimum differentiation or do not have pure equilibria at all. In particular, it was recently proven for a generalized model which incorporates negative network externalities and which contains Hotelling's model and classical selfish load balancing as special cases, that the unique equilibria do not adhere to minimum differentiation. Furthermore, it was shown that for a significant parameter range pure equilibria do not exist. We derive a sharp contrast to these previous results by investigating Hotelling's model with negative network externalities from an entirely new angle: approximate pure subgame perfect equilibria. This approach allows us to prove analytically and via agent-based simulations that approximate equilibria having good approximation guarantees and that adhere to minimum differentiation exist for the full parameter range of the model. Moreover, we show that the obtained approximate equilibria have high social welfare.}}, author = {{Feldotto, Matthias and Lenzner, Pascal and Molitor, Louise and Skopalik, Alexander}}, booktitle = {{Proceedings of the 18th International Conference on Autonomous Agents and MultiAgent Systems}}, location = {{Montreal QC, Canada}}, pages = {{1949----1951}}, publisher = {{International Foundation for Autonomous Agents and Multiagent Systems}}, title = {{{ From Hotelling to Load Balancing: Approximation and the Principle of Minimum Differentiation}}}, year = {{2019}}, } @misc{10344, author = {{Pukrop, Simon}}, publisher = {{Universität Paderborn}}, title = {{{Scheduling Algorithms for Multi-Operation Jobs with Setups on a Single Machine}}}, year = {{2019}}, } @inproceedings{2484, abstract = {{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.}}, author = {{Feldkord, Björn and Feldotto, Matthias and Gupta, Anupam and Guruganesh, Guru and Kumar, Amit and Riechers, Sören and Wajc, David}}, booktitle = {{45th International Colloquium on Automata, Languages, and Programming (ICALP 2018)}}, editor = {{Chatzigiannakis, Ioannis and Kaklamanis, Christos and Marx, Dániel and Sannella, Donald}}, isbn = {{978-3-95977-076-7}}, issn = {{1868-8969}}, location = {{Prag}}, pages = {{51:1--51:24}}, publisher = {{Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik}}, title = {{{Fully-Dynamic Bin Packing with Little Repacking}}}, doi = {{10.4230/LIPIcs.ICALP.2018.51}}, volume = {{107}}, year = {{2018}}, } @inproceedings{2485, author = {{Feldkord, Björn and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedings of the 30th ACM Symposium on Parallelism in Algorithms and Architectures (SPAA)}}, location = {{Wien}}, pages = {{373 -- 381 }}, publisher = {{ACM}}, title = {{{Online Facility Location with Mobile Facilities}}}, doi = {{10.1145/3210377.3210389}}, year = {{2018}}, } @misc{25121, abstract = {{We consider a group of $n$ autonomous mobile robots of which $m$ are stationary thus cannot move. Robots are represented by points in the Euclidean plane. They have no memory, do not communicate or share a common coordinate system and they move solely based on the positioning of other robots within their limited viewing range of 1. The goal is to gather the robots inside of the convex hull of all stationary robots. A variant of this problem, the general gathering problem, has been studied in various different time models. In this work, we consider a continuous time model, where robots continuously observe their neighbors, compute the next target of movement and move with a speed limit of 1 at any time. Regarding the robots' local strategy, we only study contracting algorithms in which every robot that is positioned on the border of the convex hull of all robots moves into this hull. We present a time bound of $\mathcal{O}(nd)$ for any general contracting algorithms in a configuration with only a single stationary robot. For configurations with more stationary robots, we prove that robots converge against the convex hull of all stationary robots and that no upper bound on the runtime exists. For the specific contracting algorithms Go-To-The-Left, Go-On-Bisector and Go-To-The-Middle, we provide linear time bounds.}}, author = {{Liedtke, David Jan}}, title = {{{Influence of Stationary Robots on Continuous Robot Formation Problems}}}, year = {{2018}}, } @unpublished{19978, abstract = {{We introduce the \emph{Online Connected Dominating Set Leasing} problem (OCDSL) in which we are given an undirected connected graph $G = (V, E)$, a set $\mathcal{L}$ of lease types each characterized by a duration and cost, and a sequence of subsets of $V$ arriving over time. A node can be leased using lease type $l$ for cost $c_l$ and remains active for time $d_l$. The adversary gives in each step $t$ a subset of nodes that need to be dominated by a connected subgraph consisting of nodes active at time $t$. The goal is to minimize the total leasing costs. OCDSL contains the \emph{Parking Permit Problem}~\cite{PPP} as a special subcase and generalizes the classical offline \emph{Connected Dominating Set} problem~\cite{Guha1998}. It has an $\Omega(\log ^2 n + \log |\mathcal{L}|)$ randomized lower bound resulting from lower bounds for the \emph{Parking Permit Problem} and the \emph{Online Set Cover} problem~\cite{Alon:2003:OSC:780542.780558,Korman}, where $|\mathcal{L}|$ is the number of available lease types and $n$ is the number of nodes in the input graph. We give a randomized $\mathcal{O}(\log ^2 n + \log |\mathcal{L}| \log n)$-competitive algorithm for OCDSL. We also give a deterministic algorithm for a variant of OCDSL in which the dominating subgraph need not be connected, the \emph{Online Dominating Set Leasing} problem. The latter is based on a simple primal-dual approach and has an $\mathcal{O}(|\mathcal{L}| \cdot \Delta)$-competitive ratio, where $\Delta$ is the maximum degree of the input graph.}}, author = {{Markarian, Christine}}, booktitle = {{arXiv:1805.02994}}, title = {{{Online Connected Dominating Set Leasing}}}, year = {{2018}}, } @inproceedings{2831, abstract = {{We consider a market where final products or services are compositions of a number of basic services. Users are asked to evaluate the quality of the composed product after purchase. The quality of the basic service influences the performance of the composed services but cannot be observed directly. The question we pose is whether it is possible to use user evaluations on composed services to assess the quality of basic services. We discuss how to combine aggregation of evaluations across users and disaggregation of information on composed services to derive valuations for the single components. As a solution we propose to use the (weighted) average as aggregation device in connection with the Shapley value as disaggregation method, since this combination fulfills natural requirements in our context. In addition, we address some occurring computational issues: We give an approximate solution concept using only a limited number of evaluations which guarantees nearly optimal results with reduced running time. Lastly, we show that a slightly modified Shapley value and the weighted average are still applicable if the evaluation profiles are incomplete.}}, author = {{Feldotto, Matthias and Haake, Claus-Jochen and Skopalik, Alexander and Stroh-Maraun, Nadja}}, booktitle = {{Proceedings of the 13th Workshop on Economics of Networks, Systems and Computation (NetEcon 2018)}}, isbn = {{978-1-4503-5916-0}}, location = {{Irvine, California, USA}}, pages = {{5:1--5:6}}, title = {{{Disaggregating User Evaluations Using the Shapley Value}}}, doi = {{10.1145/3230654.3230659}}, year = {{2018}}, } @article{2848, author = {{Li, Shouwei and Markarian, Christine and Meyer auf der Heide, Friedhelm}}, journal = {{Algorithmica}}, number = {{5}}, pages = {{1556–1574}}, publisher = {{Springer}}, title = {{{Towards Flexible Demands in Online Leasing Problems. }}}, doi = {{10.1007/s00453-018-0420-y}}, volume = {{80}}, year = {{2018}}, } @article{2849, author = {{Abu-Khzam, Faisal N. and Markarian, Christine and Meyer auf der Heide, Friedhelm and Schubert, Michael}}, journal = {{Theory of Computing Systems}}, publisher = {{Springer}}, title = {{{Approximation and Heuristic Algorithms for Computing Backbones in Asymmetric Ad-hoc Networks}}}, doi = {{10.1007/s00224-017-9836-z}}, year = {{2018}}, } @inproceedings{2850, author = {{Hamann, Heiko and Markarian, Christine and Meyer auf der Heide, Friedhelm and Wahby, Mostafa}}, booktitle = {{Ninth International Conference on Fun with Algorithms (FUN)}}, title = {{{Pick, Pack, & Survive: Charging Robots in a Modern Warehouse based on Online Connected Dominating Sets}}}, doi = {{10.4230/LIPIcs.FUN.2018.22}}, year = {{2018}}, } @inproceedings{24396, abstract = {{We study the Online Prize-collecting Node-weighted Steiner Forest problem (OPC-NWSF) in which we are given an undirected graph \(G=(V, E)\) with \(|V| = n\) and node-weight function \(w: V \rightarrow \mathcal {R}^+\). A sequence of k pairs of nodes of G, each associated with a penalty, arrives online. OPC-NWSF asks to construct a subgraph H such that each pair \(\{s, t\}\) is either connected (there is a path between s and t in H) or its associated penalty is paid. The goal is to minimize the weight of H and the total penalties paid. The current best result for OPC-NWSF is a randomized \(\mathcal {O}(\log ^4 n)\)-competitive algorithm due to Hajiaghayi et al. (ICALP 2014). We improve this by proposing a randomized \(\mathcal {O}(\log n \log k)\)-competitive algorithm for OPC-NWSF, which is optimal up to constant factor since OPC-NWSF has a randomized lower bound of \(\varOmega (\log ^2 n)\) due to Korman [11]. Moreover, our result also implies an improvement for two special cases of OPC-NWSF, the Online Prize-collecting Node-weighted Steiner Tree problem (OPC-NWST) and the Online Node-weighted Steiner Forest problem (ONWSF). In OPC-NWST, there is a distinguished node which is one of the nodes in each pair. In ONWSF, all penalties are set to infinity. The currently best known results for OPC-NWST and ONWSF are a randomized \(\mathcal {O}(\log ^3 n)\)-competitive algorithm due to Hajiaghayi et al. (ICALP 2014) and a randomized \(\mathcal {O}(\log n \log ^2 k)\)-competitive algorithm due to Hajiaghayi et al. (FOCS 2013), respectively.}}, author = {{Markarian, Christine}}, booktitle = {{International Workshop on Combinatorial Algorithms (IWOCA)}}, issn = {{0302-9743}}, title = {{{An Optimal Algorithm for Online Prize-Collecting Node-Weighted Steiner Forest}}}, doi = {{10.1007/978-3-319-94667-2_18}}, year = {{2018}}, } @article{3551, author = {{König, Jürgen and Mäcker, Alexander and Meyer auf der Heide, Friedhelm and Riechers, Sören}}, journal = {{Journal of Combinatorial Optimization}}, number = {{4}}, pages = {{1356--1379}}, title = {{{Scheduling with interjob communication on parallel processors}}}, doi = {{10.1007/s10878-018-0325-3}}, volume = {{36}}, year = {{2018}}, } @misc{3851, author = {{Koop, Samuel}}, publisher = {{Universität Paderborn}}, title = {{{Congestion Games mit gewichteten Strategien}}}, year = {{2018}}, } @inproceedings{17651, abstract = {{Consider mitigating the effects of denial of service or of malicious traffic in networks by deleting edges. Edge deletion reduces the DoS or the number of the malicious flows, but it also inadvertently removes some of the desired flows. To model this important problem, we formulate two problems: (1) remove all the undesirable flows while minimizing the damage to the desirable ones and (2) balance removing the undesirable flows and not removing too many of the desirable flows. We prove these problems are equivalent to important theoretical problems, thereby being important not only practically but also theoretically, and very hard to approximate in a general network. We employ reductions to nonetheless approximate the problem and also provide a greedy approximation. When the network is a tree, the problems are still MAX SNP-hard, but we provide a greedy-based 2l-approximation algorithm, where l is the longest desirable flow. We also provide an algorithm, approximating the first and the second problem within {\$}{\$}2 {\backslash}sqrt{\{} 2{\backslash}left| E {\backslash}right| {\}}{\$}{\$}and {\$}{\$}2 {\backslash}sqrt{\{}2 ({\backslash}left| E {\backslash}right| + {\backslash}left| {\backslash}text {\{}undesirable flows{\}} {\backslash}right| ){\}}{\$}{\$}, respectively, where E is the set of the edges of the network. We also provide a fixed-parameter tractable (FPT) algorithm. Finally, if the tree has a root such that every flow in the tree flows on the path from the root to a leaf, we solve the problem exactly using dynamic programming.}}, author = {{Polevoy, Gleb and Trajanovski, Stojan and Grosso, Paola and de Laat, Cees}}, booktitle = {{Combinatorial Optimization and Applications}}, editor = {{Kim, Donghyun and Uma, R. N. and Zelikovsky, Alexander}}, isbn = {{978-3-030-04651-4}}, keywords = {{flow, Red-Blue Set Cover, Positive-Negative Partial Set Cover, approximation, tree, MAX SNP-hard, root, leaf, dynamic programming, FPT}}, pages = {{217--232}}, publisher = {{Springer International Publishing}}, title = {{{Removing Undesirable Flows by Edge Deletion}}}, year = {{2018}}, } @article{17666, abstract = {{Software Defined Networks (SDN) and Network Function Virtualisation (NFV) provide the basis for autonomous response and mitigation against attacks on networked computer infrastructures. We propose a new framework that uses SDNs and NFV to achieve this goal: Secure Autonomous Response Network (SARNET). In a SARNET, an agent running a control loop constantly assesses the security state of the network by means of observables. The agent reacts to and resolves security problems, while learning from its previous decisions. Two main metrics govern the decision process in a SARNET: impact and efficiency; these metrics can be used to compare and evaluate countermeasures and are the building blocks for self-learning SARNETs that exhibit autonomous response. In this paper we present the software implementation of the SARNET framework, evaluate it in a real-life network and discuss the tradeoffs between parameters used by the SARNET agent and the efficiency of its actions.}}, author = {{Koning, R. and de Graaff, B. and Polevoy, Gleb and Meijer, R. and de Laat, C. and Grosso, P.}}, issn = {{0167-739X}}, journal = {{Future Generation Computer Systems}}, keywords = {{Software defined networks, Network function virtualization, Cyber attacks, Cyber security, Defense efficiency, Overlay networks}}, title = {{{Measuring the efficiency of SDN mitigations against attacks on computer infrastructures}}}, doi = {{https://doi.org/10.1016/j.future.2018.08.011}}, year = {{2018}}, } @article{63, author = {{Althaus, Ernst and Brinkmann, Andre and Kling, Peter and Meyer auf der Heide, Friedhelm and Nagel, Lars and Riechers, Sören and Sgall, Jiri and Suess, Tim}}, journal = {{Journal of Scheduling}}, number = {{1}}, pages = {{77--92}}, publisher = {{Springer}}, title = {{{Scheduling Shared Continuous Resources on Many-Cores}}}, doi = {{10.1007/s10951-017-0518-0}}, volume = {{21}}, year = {{2018}}, } @inproceedings{4411, abstract = {{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.}}, author = {{Knollmann, Till and Scheideler, Christian}}, booktitle = {{Proceedings of the 20th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS)}}, editor = {{Izumi, Taisuke and Kuznetsov, Petr}}, keywords = {{Self-Stabilizing, Prefix Search, Distributed Data Structure}}, location = {{Tokyo}}, publisher = {{Springer, Cham}}, title = {{{A Self-Stabilizing Hashed Patricia Trie}}}, doi = {{10.1007/978-3-030-03232-6_1}}, volume = {{11201}}, year = {{2018}}, } @inproceedings{4563, abstract = {{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. }}, author = {{Jung, Daniel and Kolb, Christina and Scheideler, Christian and Sundermeier, Jannik}}, booktitle = {{Proceedings of the 14th International Symposium on Algorithms and Experiments for Wireless Networks (ALGOSENSORS) }}, keywords = {{greedy routing, ad hoc networks, convex hulls, c-competitiveness}}, location = {{Helsinki}}, publisher = {{Springer}}, title = {{{Competitive Routing in Hybrid Communication Networks}}}, year = {{2018}}, } @inproceedings{4565, author = {{Jung, Daniel and Kolb, Christina and Scheideler, Christian and Sundermeier, Jannik}}, booktitle = {{Proceedings of the 30th on Symposium on Parallelism in Algorithms and Architectures (SPAA)}}, isbn = {{9781450357999}}, location = {{Wien}}, publisher = {{ACM Press}}, title = {{{Brief Announcement: Competitive Routing in Hybrid Communication Networks}}}, doi = {{10.1145/3210377.3210663}}, year = {{2018}}, } @inproceedings{7570, author = {{Meyer auf der Heide, Friedhelm and Schaefer, Johannes Sebastian}}, booktitle = {{Proceedings of the 30th on Symposium on Parallelism in Algorithms and Architectures - SPAA '18}}, isbn = {{9781450357999}}, location = {{Vienna}}, publisher = {{ACM Press}}, title = {{{Brief Announcement: Communication in Systems of Home Based Mobile Agents}}}, doi = {{10.1145/3210377.3210662}}, year = {{2018}}, } @inproceedings{4375, abstract = {{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.}}, author = {{Benter, Markus and Knollmann, Till and Meyer auf der Heide, Friedhelm and Setzer, Alexander and Sundermeier, Jannik}}, booktitle = {{Proceedings of the 4th International Symposium on Algorithmic Aspects of Cloud Computing (ALGOCLOUD)}}, keywords = {{Distributed Storage, Multi-Dimensional Range Queries, Peer-to-Peer, Hilbert Curve}}, location = {{Helsinki}}, title = {{{A Peer-to-Peer based Cloud Storage supporting orthogonal Range Queries of arbitrary Dimension}}}, doi = {{10.1007/978-3-030-19759-9_4}}, year = {{2018}}, } @misc{5403, author = {{Geromel, Marcel}}, publisher = {{Universität Paderborn}}, title = {{{Mobile Facility Leasing}}}, year = {{2018}}, } @misc{5404, author = {{Kolpaczki, Patrick Irenäus}}, publisher = {{Universität Paderborn}}, title = {{{Online Algorithmen für das k-Page Migration Problem}}}, year = {{2018}}, } @article{669, abstract = {{We study a new class of games which generalizes congestion games andits bottleneck variant. We introduce congestion games with mixed objectives to modelnetwork scenarios in which players seek to optimize for latency and bandwidths alike.We characterize the (non-)existence of pure Nash equilibria (PNE), the convergenceof improvement dynamics, the quality of equilibria and show the complexity of thedecision problem. For games that do not possess PNE we give bounds on the approx-imation ratio of approximate pure Nash equilibria.}}, author = {{Feldotto, Matthias and Leder, Lennart and Skopalik, Alexander}}, issn = {{1382-6905}}, journal = {{Journal of Combinatorial Optimization}}, number = {{4}}, pages = {{1145--1167}}, publisher = {{Springer Nature}}, title = {{{Congestion games with mixed objectives}}}, doi = {{10.1007/s10878-017-0189-y}}, volume = {{36}}, year = {{2018}}, } @misc{1186, author = {{Kemper, Arne}}, publisher = {{Universität Paderborn}}, title = {{{Pure Nash Equilibria in Robust Congestion Games via Potential Functions}}}, year = {{2018}}, } @misc{1187, author = {{Nachtigall, Marcel}}, publisher = {{Universität Paderborn}}, title = {{{Scenario-driven Strategy Analysis in a n-player Composition Game Model}}}, year = {{2018}}, } @misc{1188, author = {{Kempf, Jérôme}}, publisher = {{Universität Paderborn}}, title = {{{Learning deterministic bandit behaviour form compositions}}}, year = {{2018}}, } @phdthesis{1209, abstract = {{My dissertation deals with the Gathering problem for swarms of n point-shaped robots on a grid, in which all robots of the swarm are supposed to gather at a previously undefined point. Special attention is paid to the strong limitation of robot capabilities. These include in particular the lack of global control, a global compass, global visibility and (global) communication skills. Furthermore, all robots are identical. The robots are given only local abilities. This includes a constant range of vision. The robots all work completely synchronously. In this work we present and analyze three different Gathering strategies in different robot models. We formally prove correctness and total running time: Chapter 4 focuses on minimizing the available robot capabilities. The underlying strategy completes the gathering in O(n^2) time. For the following Chapters 5 and 6, the aim is to optimize the total running time under using only local robot capabilities: We additionally allow a constant-sized memory and a constant number of locally visible statuses (lights, flags). For the strategies of both chapters we show an asymptotically optimal running time of O(n). Unlike in Chapters 4 and 5, we additionally restrict connectivity and vision to an initially given chain connectivity in Chapter 6, where two chain neighbors must have a distance of 1 from each other. A robot can only see and interact with a constant number of its direct chain neighbors.}}, author = {{Jung, Daniel}}, isbn = {{978-3-942647-99-1}}, publisher = {{Universität Paderborn}}, title = {{{Local Strategies for Swarm Formations on a Grid}}}, doi = {{10.17619/UNIPB/1-271}}, year = {{2018}}, } @inbook{16392, author = {{Feldkord, Björn and Malatyali, Manuel and Meyer auf der Heide, Friedhelm}}, booktitle = {{Progress in Pattern Recognition, Image Analysis, Computer Vision, and Applications}}, isbn = {{9783319125671}}, issn = {{0302-9743}}, title = {{{A Dynamic Distributed Data Structure for Top-k and k-Select Queries}}}, doi = {{10.1007/978-3-319-98355-4_18}}, year = {{2018}}, } @article{1369, abstract = {{In budget games, players compete over resources with finite budgets. For every resource, a player has a specific demand and as a strategy, he chooses a subset of resources. If the total demand on a resource does not exceed its budget, the utility of each player who chose that resource equals his demand. Otherwise, the budget is shared proportionally. In the general case, pure Nash equilibria (NE) do not exist for such games. In this paper, we consider the natural classes of singleton and matroid budget games with additional constraints and show that for each, pure NE can be guaranteed. In addition, we introduce a lexicographical potential function to prove that every matroid budget game has an approximate pure NE which depends on the largest ratio between the different demands of each individual player.}}, author = {{Drees, Maximilian and Feldotto, Matthias and Riechers, Sören and Skopalik, Alexander}}, issn = {{1382-6905}}, journal = {{Journal of Combinatorial Optimization}}, publisher = {{Springer Nature}}, title = {{{Pure Nash equilibria in restricted budget games}}}, doi = {{10.1007/s10878-018-0269-7}}, year = {{2018}}, } @phdthesis{19604, author = {{Li, Shouwei}}, title = {{{Parallel fixed parameter tractable problems}}}, doi = {{10.17619/UNIPB/1-252}}, year = {{2017}}, } @inproceedings{2851, author = {{Markarian, Christine}}, booktitle = {{International Conference on Operations Research (OR)}}, location = {{Berlin}}, title = {{{Leasing with Uncertainty}}}, doi = {{10.1007/978-3-319-89920-6_57}}, year = {{2017}}, } @inproceedings{24398, abstract = {{Through this study, we introduce the idea of applying scheduling techniques to allocate spatial resources that are shared among multiple robots moving in a static environment and having temporal constraints on the arrival time to destinations. To illustrate this idea, we present an exemplified algorithm that plans and assigns a motion path to each robot. The considered problem is particularly challenging because: (i) the robots share the same environment and thus the planner must take into account overlapping paths which cannot happen at the same time; (ii) there are time deadlines thus the planner must deal with temporal constraints; (iii) new requests arrive without a priori knowledge thus the planner must be able to add new paths online and adjust old plans; (iv) the robot motion is subject to noise thus the planner must be reactive to adapt to online changes. We showcase the functioning of the proposed algorithm through a set of agent-based simulations.}}, author = {{Khaluf, Yara and Markarian, Christine and Simoens, Pieter and Reina, Andreagiovanni}}, booktitle = {{International Conference on Practical Applications of Agents and Multi-Agent Systems (PAAMS 2017)}}, issn = {{0302-9743}}, title = {{{Scheduling Access to Shared Space in Multi-robot Systems}}}, doi = {{10.1007/978-3-319-59930-4_12}}, year = {{2017}}, } @inproceedings{112, abstract = {{We study a model of selfish resource allocation that seeks to incorporate dependencies among resources as they exist in in modern networked environments. Our model is inspired by utility functions with constant elasticity of substitution (CES) which is a well-studied model in economics. We consider congestion games with different aggregation functions. In particular, we study $L_p$ norms and analyze the existence and complexity of (approximate) pure Nash equilibria. Additionally, we give an almost tight characterization based on monotonicity properties to describe the set of aggregation functions that guarantee the existence of pure Nash equilibria.}}, author = {{Feldotto, Matthias and Leder, Lennart and Skopalik, Alexander}}, booktitle = {{Proceedings of the 10th International Conference on Algorithms and Complexity (CIAC)}}, pages = {{222----233}}, title = {{{Congestion Games with Complementarities}}}, doi = {{10.1007/978-3-319-57586-5_19}}, year = {{2017}}, } @inproceedings{113, abstract = {{We study the computation of approximate pure Nash equilibria in Shapley value (SV) weighted congestion games, introduced in [19]. This class of games considers weighted congestion games in which Shapley values are used as an alternative (to proportional shares) for distributing the total cost of each resource among its users. We focus on the interesting subclass of such games with polynomial resource cost functions and present an algorithm that computes approximate pure Nash equilibria with a polynomial number of strategy updates. Since computing a single strategy update is hard, we apply sampling techniques which allow us to achieve polynomial running time. The algorithm builds on the algorithmic ideas of [7], however, to the best of our knowledge, this is the first algorithmic result on computation of approximate equilibria using other than proportional shares as player costs in this setting. We present a novel relation that approximates the Shapley value of a player by her proportional share and vice versa. As side results, we upper bound the approximate price of anarchy of such games and significantly improve the best known factor for computing approximate pure Nash equilibria in weighted congestion games of [7].}}, author = {{Feldotto, Matthias and Gairing, Martin and Kotsialou, Grammateia and Skopalik, Alexander}}, booktitle = {{Proceedings of the 13th International Conference on Web and Internet Economics (WINE)}}, title = {{{Computing Approximate Pure Nash Equilibria in Shapley Value Weighted Congestion Games}}}, doi = {{10.1007/978-3-319-71924-5_14}}, year = {{2017}}, } @inproceedings{17652, author = {{Polevoy, Gleb and Trajanovski, Stojan and Grosso, Paola and de Laat, Cees}}, booktitle = {{Combinatorial Optimization and Applications: 11th International Conference, COCOA 2017, Shanghai, China, December 16-18, 2017, Proceedings, Part I}}, isbn = {{978-3-319-71150-8}}, keywords = {{flow, filter, MMSA, set cover, approximation, local ratio algorithm}}, pages = {{3--17}}, publisher = {{Springer International Publishing}}, title = {{{Filtering Undesirable Flows in Networks}}}, doi = {{10.1007/978-3-319-71150-8_1}}, year = {{2017}}, } @inproceedings{17653, author = {{Polevoy, Gleb and de Weerdt, M.M.}}, booktitle = {{Proceedings of the 29th Benelux Conference on Artificial Intelligence}}, keywords = {{interaction, reciprocation, contribute, shared effort, curbing, convergence, threshold, Nash equilibrium, social welfare, efficiency, price of anarchy, price of stability}}, publisher = {{Springer}}, title = {{{Reciprocation Effort Games}}}, year = {{2017}}, } @inproceedings{17654, author = {{Polevoy, Gleb and de Weerdt, M.M.}}, booktitle = {{Proceedings of the 29th Benelux Conference on Artificial Intelligence}}, keywords = {{agents, projects, contribute, shared effort game, competition, quota, threshold, Nash equilibrium, social welfare, efficiency, price of anarchy, price of stability}}, publisher = {{Springer}}, title = {{{Competition between Cooperative Projects}}}, year = {{2017}}, } @unpublished{17811, abstract = {{We consider a swarm of $n$ autonomous mobile robots, distributed on a 2-dimensional grid. A basic task for such a swarm is the gathering process: All robots have to gather at one (not predefined) place. A common local model for extremely simple robots is the following: The robots do not have a common compass, only have a constant viewing radius, are autonomous and indistinguishable, can move at most a constant distance in each step, cannot communicate, are oblivious and do not have flags or states. The only gathering algorithm under this robot model, with known runtime bounds, needs $\mathcal{O}(n^2)$ rounds and works in the Euclidean plane. The underlying time model for the algorithm is the fully synchronous $\mathcal{FSYNC}$ model. On the other side, in the case of the 2-dimensional grid, the only known gathering algorithms for the same time and a similar local model additionally require a constant memory, states and "flags" to communicate these states to neighbors in viewing range. They gather in time $\mathcal{O}(n)$. In this paper we contribute the (to the best of our knowledge) first gathering algorithm on the grid that works under the same simple local model as the above mentioned Euclidean plane strategy, i.e., without memory (oblivious), "flags" and states. We prove its correctness and an $\mathcal{O}(n^2)$ time bound in the fully synchronous $\mathcal{FSYNC}$ time model. This time bound matches the time bound of the best known algorithm for the Euclidean plane mentioned above. We say gathering is done if all robots are located within a $2\times 2$ square, because in $\mathcal{FSYNC}$ such configurations cannot be solved.}}, author = {{Fischer, Matthias and Jung, Daniel and Meyer auf der Heide, Friedhelm}}, booktitle = {{arXiv:1702.03400}}, title = {{{Gathering Anonymous, Oblivious Robots on a Grid}}}, year = {{2017}}, } @inproceedings{79, abstract = {{Consider a problem in which $n$ jobs that are classified into $k$ types arrive over time at their release times and are to be scheduled on a single machine so as to minimize the maximum flow time.The machine requires a setup taking $s$ time units whenever it switches from processing jobs of one type to jobs of a different type.We consider the problem as an online problem where each job is only known to the scheduler as soon as it arrives and where the processing time of a job only becomes known upon its completion (non-clairvoyance).We are interested in the potential of simple ``greedy-like'' algorithms.We analyze a modification of the FIFO strategy and show its competitiveness to be $\Theta(\sqrt{n})$, which is optimal for the considered class of algorithms.For $k=2$ types it achieves a constant competitiveness.Our main insight is obtained by an analysis of the smoothed competitiveness.If processing times $p_j$ are independently perturbed to $\hat p_j = (1+X_j)p_j$, we obtain a competitiveness of $O(\sigma^{-2} \log^2 n)$ when $X_j$ is drawn from a uniform or a (truncated) normal distribution with standard deviation $\sigma$.The result proves that bad instances are fragile and ``practically'' one might expect a much better performance than given by the $\Omega(\sqrt{n})$-bound.}}, author = {{Mäcker, Alexander and Malatyali, Manuel and Meyer auf der Heide, Friedhelm and Riechers, Sören}}, booktitle = {{Proceedings of the 15th Workshop on Approximation and Online Algorithms (WAOA)}}, pages = {{207--222}}, publisher = {{Springer}}, title = {{{Non-Clairvoyant Scheduling to Minimize Max Flow Time on a Machine with Setup Times}}}, doi = {{10.1007/978-3-319-89441-6}}, volume = {{10787}}, year = {{2017}}, } @inproceedings{82, abstract = {{Many graph problems such as maximum cut, chromatic number, hamiltonian cycle, and edge dominating set are known to be fixed-parameter tractable (FPT) when parameterized by the treewidth of the input graphs, but become W-hard with respect to the clique-width parameter. Recently, Gajarský et al. proposed a new parameter called modular-width using the notion of modular decomposition of graphs. They showed that the chromatic number problem and the partitioning into paths problem, and hence hamiltonian path and hamiltonian cycle, are FPT when parameterized by this parameter. In this paper, we study modular-width in parameterized parallel complexity and show that the weighted maximum clique problem and the maximum matching problem are fixed-parameter parallel-tractable (FPPT) when parameterized by this parameter.}}, author = {{Abu-Khzam, Faisal N. and Li, Shouwei and Markarian, Christine and Meyer auf der Heide, Friedhelm and Podlipyan, Pavel}}, booktitle = {{Proceedings of the 11th International Workshop on Frontiers in Algorithmics (FAW)}}, pages = {{139--150}}, title = {{{Modular-Width: An Auxiliary Parameter for Parameterized Parallel Complexity}}}, doi = {{10.1007/978-3-319-59605-1_13}}, year = {{2017}}, } @inproceedings{59, abstract = {{We consider a scheduling problem on $m$ identical processors sharing an arbitrarily divisible resource. In addition to assigning jobs to processors, the scheduler must distribute the resource among the processors (e.g., for three processors in shares of 20\%, 15\%, and 65\%) and adjust this distribution over time. Each job $j$ comes with a size $p_j \in \mathbb{R}$ and a resource requirement $r_j > 0$. Jobs do not benefit when receiving a share larger than $r_j$ of the resource. But providing them with a fraction of the resource requirement causes a linear decrease in the processing efficiency. We seek a (non-preemptive) job and resource assignment minimizing the makespan.Our main result is an efficient approximation algorithm which achieves an approximation ratio of $2 + 1/(m-2)$. It can be improved to an (asymptotic) ratio of $1 + 1/(m-1)$ if all jobs have unit size. Our algorithms also imply new results for a well-known bin packing problem with splittable items and a restricted number of allowed item parts per bin.Based upon the above solution, we also derive an approximation algorithm with similar guarantees for a setting in which we introduce so-called tasks each containing several jobs and where we are interested in the average completion time of tasks (a task is completed when all its jobs are completed).}}, author = {{Kling, Peter and Mäcker, Alexander and Riechers, Sören and Skopalik, Alexander}}, booktitle = {{Proceedings of the 29th ACM Symposium on Parallelism in Algorithms and Architectures (SPAA)}}, pages = {{123----132}}, title = {{{Sharing is Caring: Multiprocessor Scheduling with a Sharable Resource}}}, doi = {{10.1145/3087556.3087578}}, year = {{2017}}, } @inproceedings{70, author = {{Feldkord, Björn and Markarian, Christine and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedings of the 11th Annual International Conference on Combinatorial Optimization and Applications (COCOA)}}, pages = {{17 -- 31}}, title = {{{Price Fluctuations in Online Leasing}}}, doi = {{10.1007/978-3-319-71147-8_2}}, year = {{2017}}, } @phdthesis{703, author = {{Podlipyan, Pavel}}, publisher = {{Universität Paderborn}}, title = {{{Local Algorithms for the Continuous Gathering Problem}}}, doi = {{10.17619/UNIPB/1-230}}, year = {{2017}}, } @phdthesis{704, author = {{Riechers, Sören}}, publisher = {{Universität Paderborn}}, title = {{{Scheduling with Scarce Resources}}}, doi = {{10.17619/UNIPB/1-231}}, year = {{2017}}, } @article{706, author = {{Mäcker, Alexander and Malatyali, Manuel and Meyer auf der Heide, Friedhelm and Riechers, Sören}}, journal = {{Journal of Combinatorial Optimization}}, number = {{4}}, pages = {{1168--1194}}, publisher = {{Springer}}, title = {{{Cost-efficient Scheduling on Machines from the Cloud}}}, doi = {{10.1007/s10878-017-0198-x}}, volume = {{36}}, year = {{2017}}, } @inproceedings{97, abstract = {{Bridging the gap between informal, imprecise, and vague user requirements descriptions and precise formalized specifications is the main task of requirements engineering. Techniques such as interviews or story telling are used when requirements engineers try to identify a user's needs. The requirements specification process is typically done in a dialogue between users, domain experts, and requirements engineers. In our research, we aim at automating the specification of requirements. The idea is to distinguish between untrained users and trained users, and to exploit domain knowledge learned from previous runs of our system. We let untrained users provide unstructured natural language descriptions, while we allow trained users to provide examples of behavioral descriptions. In both cases, our goal is to synthesize formal requirements models similar to statecharts. From requirements specification processes with trained users, behavioral ontologies are learned which are later used to support the requirements specification process for untrained users. Our research method is original in combining natural language processing and search-based techniques for the synthesis of requirements specifications. Our work is embedded in a larger project that aims at automating the whole software development and deployment process in envisioned future software service markets.}}, author = {{van Rooijen, Lorijn and Bäumer, Frederik Simon and Platenius, Marie Christin and Geierhos, Michaela and Hamann, Heiko and Engels, Gregor}}, booktitle = {{2017 IEEE 25th International Requirements Engineering Conference Workshops (REW)}}, isbn = {{978-1-5386-3489-9}}, keywords = {{Software, Unified modeling language, Requirements engineering, Ontologies, Search problems, Natural languages}}, location = {{Lisbon, Portugal}}, pages = {{379--385}}, publisher = {{IEEE}}, title = {{{From User Demand to Software Service: Using Machine Learning to Automate the Requirements Specification Process}}}, doi = {{10.1109/REW.2017.26}}, year = {{2017}}, } @inproceedings{55, abstract = {{We introduce the mobile server problem, inspired by current trends to move computational tasks from cloud structures to multiple devices close to the end user. An example for this are embedded systems in autonomous cars that communicate in order to coordinate their actions. Our model is a variant of the classical Page Migration Problem. Moreformally, we consider a mobile server holding a data page.The server can move in the Euclidean space (of arbitrary dimension). In every round, requests for data items from the page pop up at arbitrary points in the space. The requests are served, each at a cost of the distance from the requesting point and the server, and the mobile server may move, at a cost D times the distance traveled for some constant D . We assume a maximum distance m the server is allowed to move per round. We show that no online algorithm can achieve a competitive ratio independent of the length of the input sequence in this setting. Hence we augment the maximum movement distance of the online algorithms to ( 1 + δ) times the maximum distance of the offline solution. We provide a deterministic algorithm which is simple to describe and works for multiple variants of our problem. The algorithm achieves almost tight competitive ratios independent of the length of the input sequence.}}, author = {{Feldkord, Björn and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedings of the 29th ACM Symposium on Parallelism in Algorithms and Architectures (SPAA)}}, pages = {{313--319}}, title = {{{The Mobile Server Problem}}}, doi = {{10.1145/3087556.3087575}}, year = {{2017}}, } @inproceedings{66, abstract = {{In budget games, players compete over resources with finite budgets. For every resource, a player has a specific demand and as a strategy, he chooses a subset of resources. If the total demand on a resource does not exceed its budget, the utility of each player who chose that resource equals his demand. Otherwise, the budget is shared proportionally. In the general case, pure Nash equilibria (NE) do not exist for such games. In this paper, we consider the natural classes of singleton and matroid budget games with additional constraints and show that for each, pure NE can be guaranteed. In addition, we introduce a lexicographical potential function to prove that every matroid budget game has an approximate pure NE which depends on the largest ratio between the different demands of each individual player.}}, author = {{Drees, Maximilian and Feldotto, Matthias and Riechers, Sören and Skopalik, Alexander}}, booktitle = {{Proceedings of the 23rd International Computing and Combinatorics Conference (COCOON)}}, pages = {{175----187}}, title = {{{Pure Nash Equilibria in Restricted Budget Games}}}, doi = {{10.1007/978-3-319-62389-4_15}}, year = {{2017}}, } @misc{695, author = {{Nowack, Joshua}}, publisher = {{Universität Paderborn}}, title = {{{On-The-Fly Konstruktion zusammenhängender Straßennetze aus gegebenen Einzelteilen}}}, year = {{2017}}, } @book{16444, author = {{Gausemeier, Jürgen and Bodden, Eric and Dressler, Falko and Dumitrescu, Roman and Meyer auf der Heide, Friedhelm and Scheytt, Christoph and Trächtler, Ansgar}}, pages = {{369}}, title = {{{Wissenschaftsforum Intelligente Technische Systeme (WInTeSys)}}}, year = {{2017}}, } @inbook{16461, author = {{Bemmann, Pascal and Biermeier, Felix and Bürmann, Jan and Kemper, Arne and Knollmann, Till and Knorr, Steffen and Kothe, Nils and Mäcker, Alexander and Malatyali, Manuel and Meyer auf der Heide, Friedhelm and Riechers, Sören and Schaefer, Johannes Sebastian and Sundermeier, Jannik}}, booktitle = {{Structural Information and Communication Complexity}}, isbn = {{9783319720494}}, issn = {{0302-9743}}, title = {{{Monitoring of Domain-Related Problems in Distributed Data Streams}}}, doi = {{10.1007/978-3-319-72050-0_13}}, year = {{2017}}, } @misc{1073, author = {{Nachtigall, Simon}}, publisher = {{Universität Paderborn}}, title = {{{Sortieren dynamischer Daten}}}, year = {{2017}}, } @misc{1074, author = {{Pukrop, Simon}}, publisher = {{Universität Paderborn}}, title = {{{Robuste Optimierung in Congestion Games}}}, year = {{2017}}, } @misc{1080, author = {{Bürmann, Jan}}, publisher = {{Universität Paderborn}}, title = {{{Complexity of Signalling in Routing Games under Uncertainty}}}, year = {{2017}}, } @misc{1081, author = {{Vijayalakshmi, Vipin Ravindran}}, publisher = {{Universität Paderborn}}, title = {{{Bounding the Inefficiency of Equilibria in Congestion Games under Taxation}}}, year = {{2017}}, } @inproceedings{1094, abstract = {{Many university students struggle with motivational problems, and gamification has the potential to address these problems. However, gamification is hardly used in education, because current approaches to gamification require instructors to engage in the time-consuming preparation of their course contents for use in quizzes, mini-games and the like. Drawing on research on limited attention and present bias, we propose a "lean" approach to gamification, which relies on gamifying learning activities (rather than learning contents) and increasing their salience. In this paper, we present the app StudyNow that implements such a lean gamification approach. With this app, we aim to enable more students and instructors to benefit from the advantages of gamification.}}, author = {{Feldotto, Matthias and John, Thomas and Kundisch, Dennis and Hemsen, Paul and Klingsieck, Katrin and Skopalik, Alexander}}, booktitle = {{Proceedings of the 12th International Conference on Design Science Research in Information Systems and Technology (DESRIST)}}, pages = {{462--467}}, title = {{{Making Gamification Easy for the Professor: Decoupling Game and Content with the StudyNow Mobile App}}}, doi = {{10.1007/978-3-319-59144-5_32}}, year = {{2017}}, } @inproceedings{1095, abstract = {{Many university students struggle with motivational problems, and gamification has the potential to address these problems. However, using gamification currently is rather tedious and time-consuming for instructors because current approaches to gamification require instructors to engage in the time-consuming preparation of course contents (e.g., for quizzes or mini-games). In reply to this issue, we propose a “lean” approach to gamification, which relies on gamifying learning activities rather than learning contents. The learning activities that are gamified in the lean approach can typically be drawn from existing course syllabi (e.g., attend certain lectures, hand in assignments, read book chapters and articles). Hence, compared to existing approaches, lean gamification substantially lowers the time requirements posed on instructors for gamifying a given course. Drawing on research on limited attention and the present bias, we provide the theoretical foundation for the lean gamification approach. In addition, we present a mobile application that implements lean gamification and outline a mixed-methods study that is currently under way for evaluating whether lean gamification does indeed have the potential to increase students’ motivation. We thereby hope to allow more students and instructors to benefit from the advantages of gamification. }}, author = {{John, Thomas and Feldotto, Matthias and Hemsen, Paul and Klingsieck, Katrin and Kundisch, Dennis and Langendorf, Mike}}, booktitle = {{Proceedings of the 25th European Conference on Information Systems (ECIS)}}, pages = {{2970--2979}}, title = {{{Towards a Lean Approach for Gamifying Education}}}, year = {{2017}}, } @article{110, abstract = {{We consider an extension of the dynamic speed scaling scheduling model introduced by Yao et al.: A set of jobs, each with a release time, deadline, and workload, has to be scheduled on a single, speed-scalable processor. Both the maximum allowed speed of the processor and the energy costs may vary continuously over time. The objective is to find a feasible schedule that minimizes the total energy costs. Theoretical algorithm design for speed scaling problems often tends to discretize problems, as our tools in the discrete realm are often better developed or understood. Using the above speed scaling variant with variable, continuous maximal processor speeds and energy prices as an example, we demonstrate that a more direct approach via tools from variational calculus can not only lead to a very concise and elegant formulation and analysis, but also avoids the “explosion of variables/constraints” that often comes with discretizing. Using well-known tools from calculus of variations, we derive combinatorial optimality characteristics for our continuous problem and provide a quite concise and simple correctness proof.}}, author = {{Antoniadis, Antonios and Kling, Peter and Ott, Sebastian and Riechers, Sören}}, journal = {{Theoretical Computer Science}}, pages = {{1--13}}, publisher = {{Elsevier}}, title = {{{Continuous Speed Scaling with Variability: A Simple and Direct Approach}}}, doi = {{10.1016/j.tcs.2017.03.021}}, year = {{2017}}, } @inproceedings{16338, abstract = {{To detect errors or find potential for improvement during the CAD-supported development of a complex technical system like modern industrial machines, the system’s virtual prototype can be examined in virtual reality (VR) in the context of virtual design reviews. Besides exploring the static shape of the examined system, observing the machines’ mechanics (e.g., motor-driven mechanisms) and transport routes for the material transport (e.g., via conveyor belts or chains, or rail-based transport systems) can play an equally important role in such a review. In practice it is often the case, that the relevant information about transport routes, or kinematic properties is either not consequently modeled in the CAD data or is lost during conversion processes. To significantly reduce the manual effort and costs for creating animations of the machines complex behavior with such limited input data for a design review, we present a set of algorithms to automatically determine geometrical properties of machine parts based only on their triangulated surfaces. The algorithms allow to detect the course of transport systems, the orientation of objects in 3d space, rotation axes of cylindrical objects and holes, the number of tooth of gears, as well as the tooth spacing of toothed racks. We implemented the algorithms in the VR system PADrend and applied them to animate virtual prototypes of real machines.}}, author = {{Brandt, Sascha and Fischer, Matthias and Gerges, Maria and Jähn, Claudius and Berssenbrügge, Jan}}, booktitle = {{Volume 1: 37th Computers and Information in Engineering Conference}}, isbn = {{9780791858110}}, location = {{Cleveland, USA}}, pages = {{91:1--91:10}}, title = {{{Automatic Derivation of Geometric Properties of Components From 3D Polygon Models}}}, doi = {{10.1115/detc2017-67528}}, volume = {{1}}, year = {{2017}}, } @inproceedings{16339, abstract = {{In der CAD-unterstützten Entwicklung von technischen Systemen (Maschinen, Anlagen etc.) werden virtuelle Prototypen im Rahmen eines virtuellen Design-Reviews mit Hilfe eines VR-Systems gesamtheitlich betrachtet, um frühzeitig Fehler und Verbesserungsbedarf zu erkennen. Ein wichtiger Untersuchungsgegenstand ist dabei die Analyse von Transportwegen für den Materialtransport mittels Fließbändern, Förderketten oder schienenbasierten Transportsystemen. Diese Transportwege werden im VR-System animiert. Problematisch dabei ist, dass derartige Transportsysteme im zugrundeliegenden CAD-Modell in der Praxis oft nicht modelliert und nur exemplarisch angedeutet werden, da diese für die Konstruktion nicht relevant sind (z.B. der Fördergurt eines Förderbandes, oder die Kette einer Förderkette), oder die Informationen über den Verlauf bei der Konvertierung der Daten in das VR-System verloren gehen. Bei der Animation dieser Transportsysteme in einem VR-System muss der Transportweg also aufwändig, manuell nachgearbeitet werden. Das Ziel dieser Arbeit ist die Reduzierung des notwendigen manuellen Nachbearbeitungsaufwandes für das Design-Review durch eine automatische Berechnung der Animationspfade entlang eines Transportsystems. Es wird ein Algorithmus vorgestellt, der es ermöglicht mit nur geringem zeitlichem Benutzeraufwand den Animationspfad aus den reinen polygonalen dreidimensionalen Daten eines Transportsystems automatisch zu rekonstruieren.}}, author = {{Brandt, Sascha and Fischer, Matthias}}, booktitle = {{Wissenschaftsforum Intelligente Technische Systeme (WInTeSys) 2017}}, location = {{Paderborn}}, pages = {{415--427}}, publisher = {{Verlagsschriftenreihe des Heinz Nixdorf Instituts, Paderborn}}, title = {{{Automatische Ableitung der Transportwege von Transportsystemen aus dem 3D-Polygonmodell}}}, volume = {{369}}, year = {{2017}}, } @inproceedings{16347, author = {{Fischer, Matthias and Jung, Daniel and Meyer auf der Heide, Friedhelm}}, booktitle = {{Algorithms for Sensor Systems - 13th International Symposium on Algorithms and Experiments for Wireless Sensor Networks, {ALGOSENSORS}}}, editor = {{Fernández Anta, Antonio and Jurdzinski, Tomasz and Mosteiro, Miguel A. and Zhang, Yanyong}}, pages = {{168--181}}, publisher = {{Springer}}, title = {{{Gathering Anonymous, Oblivious Robots on a Grid}}}, doi = {{10.1007/978-3-319-72751-6_13}}, volume = {{10718}}, year = {{2017}}, } @inproceedings{16348, author = {{Biermeier, Felix and Feldkord, Björn and Malatyali, Manuel and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedings of the 15th Workshop on Approximation and Online Algorithms (WAOA)}}, pages = {{285 -- 300}}, publisher = {{Springer}}, title = {{{A Communication-Efficient Distributed Data Structure for Top-k and k-Select Queries}}}, doi = {{10.1007/978-3-319-89441-6_21}}, year = {{2017}}, } @inproceedings{16349, author = {{Podlipyan, Pavel and Li, Shouwei and Markarian, Christine and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedings of the 13th International Symposium on Algorithms and Experiments for Wireless Networks (ALGOSENSORS)}}, pages = {{182--197}}, title = {{{A Continuous Strategy for Collisionless Gathering}}}, doi = {{10.1007/978-3-319-72751-6_14 }}, year = {{2017}}, } @inproceedings{19961, abstract = {{The self-organizing bio-hybrid collaboration ofrobots and natural plants allows for a variety of interestingapplications. As an example we investigate how robots can beused to control the growth and motion of a natural plant, using LEDs to provide stimuli. We follow an evolutionaryrobotics approach where task performance is determined bymonitoring the plant's reaction. First, we do initial plantexperiments with simple, predetermined controllers. Then weuse image sampling data as a model of the dynamics ofthe plant tip xy position. Second, we use this approach toevolve robot controllers in simulation. The task is to makethe plant approach three predetermined, distinct points in anxy-plane. Finally, we test the evolved controllers in real plantexperiments and find that we cross the reality gap successfully. We shortly describe how we have extended from plant tipto many points on the plant, for a model of the plant stemdynamics. Future work will extend to two-axes image samplingfor a 3-d approach.}}, author = {{Wahby, Mostafa and Hofstadler, Daniel Nicolas and Heinrich, Mary Katherine and Zahadat, Payam and Hamann, Heiko}}, booktitle = {{Proc. of the 10th International Conference on Self-Adaptive and Self-Organizing Systems}}, isbn = {{9781509035342}}, title = {{{An Evolutionary Robotics Approach to the Control of Plant Growth and Motion: Modeling Plants and Crossing the Reality Gap}}}, doi = {{10.1109/saso.2016.8}}, year = {{2016}}, } @inproceedings{19968, author = {{Heinrich, Mary Katherine and Wahby, Mostafa and Divband Soorati, Mohammad and Hofstadler, Daniel Nicolas and Zahadat, Payam and Ayres, Phil and Stoy, Kasper and Hamann, Heiko}}, booktitle = {{Proc. of the 1st International Workshop on Self-Organising Construction (SOCO)}}, isbn = {{9781509036516}}, title = {{{Self-Organized Construction with Continuous Building Material: Higher Flexibility Based on Braided Structures}}}, doi = {{10.1109/fas-w.2016.43}}, year = {{2016}}, }