@inproceedings{580, abstract = {{We present and study a new model for energy-aware and profit-oriented scheduling on a single processor.The processor features dynamic speed scaling as well as suspension to a sleep mode.Jobs arrive over time, are preemptable, and have different sizes, values, and deadlines.On the arrival of a new job, the scheduler may either accept or reject the job.Accepted jobs need a certain energy investment to be finished in time, while rejected jobs cause costs equal to their values.Here, power consumption at speed $s$ is given by $P(s)=s^{\alpha}+\beta$ and the energy investment is power integrated over time.Additionally, the scheduler may decide to suspend the processor to a sleep mode in which no energy is consumed, though awaking entails fixed transition costs $\gamma$.The objective is to minimize the total value of rejected jobs plus the total energy.Our model combines aspects from advanced energy conservation techniques (namely speed scaling and sleep states) and profit-oriented scheduling models.We show that \emph{rejection-oblivious} schedulers (whose rejection decisions are not based on former decisions) have – in contrast to the model without sleep states – an unbounded competitive ratio.It turns out that the jobs' value densities (the ratio between a job's value and its work) are crucial for the performance of such schedulers.We give an algorithm whose competitiveness nearly matches the lower bound w.r.t\text{.} the maximum value density.If the maximum value density is not too large, the competitiveness becomes $\alpha^{\alpha}+2e\alpha$.Also, we show that it suffices to restrict the value density of low-value jobs only.Using a technique from \cite{Chan:2010} we transfer our results to processors with a fixed maximum speed.}}, author = {{Cord-Landwehr, Andreas and Kling, Peter and Mallmann Trenn, Fredrik}}, booktitle = {{Proceedings of the 1st Mediterranean Conference on Algorithms (MedAlg)}}, editor = {{Even, Guy and Rawitz, Dror}}, pages = {{218--231}}, title = {{{Slow Down & Sleep for Profit in Online Deadline Scheduling}}}, doi = {{10.1007/978-3-642-34862-4_17}}, year = {{2012}}, } @inproceedings{581, abstract = {{Nanoparticles are getting more and more in the focus of the scientic community since the potential for the development of very small particles interacting with each other and completing medical and other tasks is getting bigger year by year. In this work we introduce a distributed local algorithm for arranging a set of nanoparticles on the discrete plane into specic geometric shapes, for instance a rectangle. The concept of a particle we use can be seen as a simple mobile robot with the following restrictions: it can only view the state of robots it is physically connected to, is anonymous, has only a constant size memory, can only move by using other particles as an anchor point on which it pulls itself alongside, and it operates in Look-Compute-Move cycles. The main result of this work is the presentation of a random distributed local algorithm which transforms any given connected set of particles into a particular geometric shape. As an example we provide a version of this algorithm for forming a rectangle with an arbitrary predened aspect ratio. To the best of our knowledge this is the rst work that considers arrangement problems for these types of robots.}}, author = {{Drees, Maximilian and Hüllmann (married name: Eikel), Martina and Koutsopoulos, Andreas and Scheideler, Christian}}, booktitle = {{Proceedings of the 26th IEEE International Parallel and Distributed Processing Symposium (IPDPS)}}, pages = {{1272--1283}}, title = {{{Self-Organizing Particle Systems}}}, doi = {{10.1109/IPDPS.2012.116}}, year = {{2012}}, } @phdthesis{601, abstract = {{Wir betrachten eine Gruppe von mobilen, autonomen Robotern in einem ebenen Gel{\"a}nde. Es gibt keine zentrale Steuerung und die Roboter m{\"u}ssen sich selbst koordinieren. Zentrale Herausforderung dabei ist, dass jeder Roboter nur seine unmittelbare Nachbarschaft sieht und auch nur mit Robotern in seiner unmittelbaren Nachbarschaft kommunizieren kann. Daraus ergeben sich viele algorithmische Fragestellungen. In dieser Arbeit wird untersucht, unter welchen Voraussetzungen die Roboter sich auf einem Punkt versammeln bzw. eine Linie zwischen zwei festen Stationen bilden k{\"o}nnen. Daf{\"u}r werden mehrere Roboter-Strategien in verschiedenen Bewegungsmodellen vorgestellt. Diese Strategien werden auf ihre Effizienz hin untersucht. Es werden obere und untere Schranken f{\"u}r die ben{\"o}tigte Anzahl Runden und die Bewegungsdistanz gezeigt. In einigen F{\"a}llen wird außerdem die ben{\"o}tigte Bewegungsdistanz mit derjenigen Bewegungsdistanz verglichen, die eine optimale globale Strategie auf der gleichen Instanz ben{\"o}tigen w{\"u}rde. So werden kompetititve Faktoren hergeleitet.}}, author = {{Kempkes, Barbara}}, isbn = {{978-3-942647-21-2}}, publisher = {{Verlagsschriftenreihe des Heinz Nixdorf Instituts, Paderborn}}, title = {{{Local strategies for robot formation problems}}}, volume = {{302}}, year = {{2012}}, } @inproceedings{619, abstract = {{Dynamics in networks is caused by a variety of reasons, like nodes moving in 2D (or 3D) in multihop cellphone networks, joins and leaves in peer-to-peer networks, evolution in social networks, and many others. In order to understand such kinds of dynamics, and to design distributed algorithms that behave well under dynamics, many ways to model dynamics are introduced and analyzed w.r.t. correctness and eciency of distributed algorithms. In [16], Kuhn, Lynch, and Oshman have introduced a very general, worst case type model of dynamics: The edge set of the network may change arbitrarily from step to step, the only restriction is that it is connected at all times and the set of nodes does not change. An extended model demands that a xed connected subnetwork is maintained over each time interval of length T (T-interval dynamics). They have presented, among others, algorithms for counting the number of nodes under such general models of dynamics.In this paper, we generalize their models and algorithms by adding random edge faults, i.e., we consider fault-prone dynamic networks: We assume that an edge currently existing may fail to transmit data with some probability p. We rst observe that strong counting, i.e., each node knows the correct count and stops, is not possible in a model with random edge faults. Our main two positive results are feasibility and runtime bounds for weak counting, i.e., stopping is no longer required (but still a correct count in each node), and for strong counting with an upper bound, i.e., an upper bound N on n is known to all nodes.}}, author = {{Brandes, Philipp and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedings of the 4th Workshop on Theoretical Aspects of Dynamic Distributed Systems (TADDS)}}, pages = {{9--14}}, title = {{{Distributed Computing in Fault-Prone Dynamic Networks}}}, doi = {{10.1145/2414815.2414818}}, year = {{2012}}, } @inproceedings{628, abstract = {{Network creation games model the creation and usage costs of networks formed by a set of selfish peers.Each peer has the ability to change the network in a limited way, e.g., by creating or deleting incident links.In doing so, a peer can reduce its individual communication cost.Typically, these costs are modeled by the maximum or average distance in the network.We introduce a generalized version of the basic network creation game (BNCG).In the BNCG (by Alon et al., SPAA 2010), each peer may replace one of its incident links by a link to an arbitrary peer.This is done in a selfish way in order to minimize either the maximum or average distance to all other peers.That is, each peer works towards a network structure that allows himself to communicate efficiently with all other peers.However, participants of large networks are seldom interested in all peers.Rather, they want to communicate efficiently with a small subset only.Our model incorporates these (communication) interests explicitly.Given peers with interests and a communication network forming a tree, we prove several results on the structure and quality of equilibria in our model.We focus on the MAX-version, i.e., each node tries to minimize the maximum distance to nodes it is interested in, and give an upper bound of O(\sqrt(n)) for the private costs in an equilibrium of n peers.Moreover, we give an equilibrium for a circular interest graph where a node has private cost Omega(\sqrt(n)), showing that our bound is tight.This example can be extended such that we get a tight bound of Theta(\sqrt(n)) for the price of anarchy.For the case of general networks we show the price of anarchy to be Theta(n).Additionally, we prove an interesting connection between a maximum independent set in the interest graph and the private costs of the peers.}}, author = {{Cord-Landwehr, Andreas and Huellmann (married name: Eikel), Martina and Kling, Peter and Setzer, Alexander}}, booktitle = {{Proceedings of the 5th International Symposium on Algorithmic Game Theory (SAGT)}}, pages = {{72----83}}, title = {{{Basic Network Creation Games with Communication Interests}}}, doi = {{10.1007/978-3-642-33996-7_7}}, year = {{2012}}, } @inproceedings{636, abstract = {{We consider an online facility location problem where clients arrive over time and their demands have to be served by opening facilities and assigning the clients to opened facilities. When opening a facility we must choose one of K different lease types to use. A lease type k has a certain lease length lk. Opening a facility i using lease type k causes a cost of f k i and ensures that i is open for the next lk time steps. In addition to costs for opening facilities, we have to take connection costs ci j into account when assigning a client j to facility i. We develop and analyze the first online algorithm for this problem that has a time-independent competitive factor.This variant of the online facility location problem was introduced by Nagarajan and Williamson [7] and is strongly related to both the online facility problem by Meyerson [5] and the parking permit problem by Meyerson [6]. Nagarajan and Williamson gave a 3-approximation algorithm for the offline problem and an O(Klogn)-competitive algorithm for the online variant. Here, n denotes the total number of clients arriving over time. We extend their result by removing the dependency on n (and thereby on the time). In general, our algorithm is O(lmax log(lmax))-competitive. Here lmax denotes the maximum lease length. Moreover, we prove that it is O(log2(lmax))-competitive for many “natural” cases. Such cases include, for example, situations where the number of clients arriving in each time step does not vary too much, or is non-increasing, or is polynomially bounded in lmax.}}, author = {{Meyer auf der Heide, Friedhelm and Pietrzyk, Peter and Kling, Peter}}, booktitle = {{Proceedings of the 19th International Colloquium on Structural Information & Communication Complexity (SIROCCO)}}, pages = {{61--72}}, title = {{{An Algorithm for Facility Leasing}}}, doi = {{10.1007/978-3-642-31104-8_6}}, year = {{2012}}, } @misc{638, author = {{Eidens, Fabian}}, publisher = {{Universität Paderborn}}, title = {{{Adaptive Verbindungsstrategien in dynamischen Suchnetzwerken}}}, year = {{2012}}, } @inbook{16445, author = {{Kempkes, Barbara and Meyer auf der Heide, Friedhelm}}, booktitle = {{Experimental Algorithms}}, isbn = {{9783642308499}}, issn = {{0302-9743}}, title = {{{Continuous Local Strategies for Robotic Formation Problems}}}, doi = {{10.1007/978-3-642-30850-5_2}}, year = {{2012}}, } @inproceedings{16446, author = {{Kempkes, Barbara and Kling, Peter and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedinbgs of the 24th ACM symposium on Parallelism in algorithms and architectures - SPAA '12}}, isbn = {{9781450312134}}, title = {{{Optimal and competitive runtime bounds for continuous, local gathering of mobile robots}}}, doi = {{10.1145/2312005.2312009}}, year = {{2012}}, } @inbook{16448, author = {{Kempkes, Barbara and Meyer auf der Heide, Friedhelm}}, booktitle = {{Algorithms for Sensor Systems}}, isbn = {{9783642282089}}, issn = {{0302-9743}}, title = {{{Local, Self-organizing Strategies for Robotic Formation Problems}}}, doi = {{10.1007/978-3-642-28209-6_2}}, year = {{2012}}, } @inproceedings{16408, abstract = {{We present a parallel rendering system for heterogeneous PC clusters to visualize massive models. One single, powerful visualization node is supported by a group of backend nodes with weak graphics performance. While the visualization node renders the visible objects, the backend nodes asynchronously perform visibility tests and supply the front end with visible scene objects. The visualization node stores only currently visible objects in its memory, while the scene is distributed among the backend nodes’ memory without redundancy. To efficiently compute the occlusion tests in spite of that each backend node stores only a fraction of the original geometry, we complete the scene by adding highly simplified versions of the objects stored on other nodes. We test our system with 15 backend nodes. It is able to render a ≈ 350,M polygons (≈ 8.5,GiB) large aircraft model with 20, to 30,fps and thus allows a walk-through in real-time. }}, author = {{Suess, Tim and Koch, Clemens and Jähn, Claudius and Fischer, Matthias and Meyer auf der Heide, Friedhelm}}, booktitle = {{Advances in Visual Computing}}, isbn = {{9783642331787}}, issn = {{0302-9743}}, pages = {{502--512}}, title = {{{Asynchronous Occlusion Culling on Heterogeneous PC Clusters for Distributed 3D Scenes}}}, doi = {{10.1007/978-3-642-33179-4_48}}, volume = {{7431}}, year = {{2012}}, } @phdthesis{19619, author = {{Korzeniowski, Miroslaw}}, isbn = {{978-3-942647-08-3}}, publisher = {{Verlagsschriftenreihe des Heinz Nixdorf Instituts, Paderborn}}, title = {{{Dynamic Load Balancing in Peer-to-Peer Networks}}}, volume = {{289}}, year = {{2011}}, } @article{19677, author = {{Briest, Patrick and Krysta, Piotr and Hoefer, Martin}}, journal = {{Algorithmica}}, pages = {{733–753}}, title = {{{Stackelberg Network Pricing Games}}}, doi = {{10.1007/s00453-010-9480-3}}, volume = {{62}}, year = {{2011}}, } @inproceedings{19845, abstract = {{In dieser Arbeit stellen wir ein flexibles System zur Entwicklung und Evaluation von 3-D-Renderingalgorithmen vor, das die Visualisierung komplexer virtueller Szenen auf einem breiten Spektrum an Geräten erlaubt. Die Aufbereitung und Echtzeitdarstellung solcher virtueller Szenen, wie sie beispielsweise aus detaillierten CAD-Daten erzeugt werden, stellt in vielerlei Hinsicht eine algorithmische und technische Herausforderung dar. Die 3-D-Szenendaten können nach dem Dateiimport aus einem Austauschformat in eine Vielzahl unterschiedlicher Datenstrukturen überführt werden. Es muss ein geeignetes Renderingverfahren ausgewählt und eingestellt werden, welches sowohl die Eigenschaften der Szene (Zahl der Polygone, Grad der Verdeckung etc.) als auch die Fähigkeiten der Hardware berücksichtigt. Auf der einen Seite stellt die Darstellung auf mobilen Endgeräten wie Smartphones besonders hohe Anforderungen aufgrund der Speicherbeschränkung und der geringen Leistungsfähigkeit der Grafikhardware. Auf der anderen Seite stehen bei Großprojektionssystemen, wie beispielsweise dem HD-Visualisierungscenter des Heinz Nixdorf Instituts, die hohe Bildqualität bei stereoskopischer Darstellung und die Unterstützung von Trackingsystemen im Vordergrund. Der Fokus des von uns entwickelten Systems PADrend liegt in der Bereitstellung einer flexiblen und leicht erweiterbaren Grundlage für die Entwicklung und Evaluation von 3-D-Renderingalgorithmen und räumlichen Datenstrukturen im Bereich der Forschung und der universitären Ausbildung. Durch den modularen Aufbau und die große Bandbreite an unterstützten Systemen wird gewährleistet, dass eine Vielzahl unterschiedlicher Entwicklungen und Anwendungen auf PADrend aufsetzen können. In diesem Artikel geben wir einen Überblick über den Aufbau und die Fähigkeiten des Systems. Des Weiteren geben wir ein Beispiel für ein Anwendungsszenario, in dem PADrend eingesetzt wird: die Visualisierung von architektonischen Modellen auf einem Multiprojektionssystem.}}, author = {{Jähn, Claudius and Petring, Ralf and Eikel, Benjamin}}, booktitle = {{Augmented & Virtual Reality in der Produktentstehung}}, pages = {{159----170}}, publisher = {{Verlagsschriftenreihe des Heinz Nixdorf Instituts, Paderborn}}, title = {{{PADrend: Platform for Algorithm Development and Rendering}}}, volume = {{295}}, year = {{2011}}, } @inproceedings{20180, abstract = {{The challenging scientific field of self-reconfiguring modular robotics (i.e., decentrally controlled 'super-robots' based on autonomous, interacting robot modules with variable morphologies) calls for novel paradigms of designing robot controllers. One option is the approach of evolutionary robotics. In this approach, the challenge is to achieve high evaluation numbers with the available resources which may even affect the feasibility of this approach. Simulations are usually applied at least in a preliminary stage of research to support controller design. However, even simulations are computationally expensive which gets even more burdensome once comprehensive studies and comparisons between different controller designs and approaches have to be done. Hence, a benchmark with low computational cost is needed that still contains the typical challenges of decentral control, is comparable, and easily manageable. We propose such a benchmark and report an empirical study of its characteristics including the transition from the single-robot setting to the multi-robot setting, typical local optima, and properties of adaptive walks through the fitness landscape.}}, author = {{Hamann, Heiko and Schmickl, Thomas and Crailsheim, Karl and Krasnogor, Natalio and Luca Lanzi, Pier}}, booktitle = {{Proceedings of the 13th Annual Genetic and Evolutionary Computation Conference, GECCO 2011}}, pages = {{195----202}}, title = {{{Coupled inverted pendulums: A benchmark for evolving decentral controllers in modular robotics}}}, doi = {{10.1145/2001576.2001604}}, year = {{2011}}, } @inproceedings{20181, abstract = {{The current definitions of emergence have no effects in the context of artificial life that could convincingly be called `constructive'. They are rather descriptive labels or tests. In order to get towards recipes of generating emergence we need to know systemic characteristics that help during the design phase of artificial life systems and worlds. In this paper, we develop and discuss five hypotheses that are not meant to be irrevocable but rather thought-provoking. We introduce two modeling approaches for Langton's ant to clarify these hypotheses. Then we discuss general properties of systems, such as (ir-)reversibility, dependence on initial states, computation, discreetness, and undecidable properties of system states.}}, author = {{Hamann, Heiko and Schmickl, Thomas and Crailsheim, Karl}}, booktitle = {{IEEE Symposium on Artificial Life (IEEE ALIFE 2011)}}, pages = {{62----69}}, title = {{{Thermodynamics of Emergence: Langton's Ant Meets Boltzmann}}}, doi = {{10.1109/ALIFE.2011.5954660}}, year = {{2011}}, } @inproceedings{20183, author = {{Hamann, Heiko and Schmickl, Thomas and Crailsheim, Karl}}, booktitle = {{10th European Conference on Artificial Life (ECAL'09)}}, isbn = {{9783642212826}}, issn = {{0302-9743}}, pages = {{442----449}}, title = {{{Evolving for Creativity: Maximizing Complexity in a Self-organized Multi-particle System}}}, doi = {{10.1007/978-3-642-21283-3_55}}, volume = {{5777}}, year = {{2011}}, } @inproceedings{20184, author = {{Hamann, Heiko and Schmickl, Thomas and Stradner, Jürgen and Crailsheim, Karl and Thenius, Rona and Fitch, Robert}}, booktitle = {{Robotic Organisms: Artificial Homeostatic Hormone System and Virtual Embryogenesis as Examples}}, title = {{{Robotic Organisms: Artificial Homeostatic Hormone System and Virtual Embryogenesis as Examples for Adaptive Reaction-Diffusion Controllers}}}, year = {{2011}}, } @inbook{20193, author = {{Hamann, Heiko and Schmickl, Thomas}}, booktitle = {{Bio-inspired Computing and Communication Networks}}, editor = {{Xiao, Yang}}, publisher = {{CRC Press}}, title = {{{{BEECLUST}: {A} Swarm Algorithm Derived from Honeybees}}}, year = {{2011}}, } @inproceedings{20194, author = {{Hamann, Heiko and Karsai, Istvan and Schmickl, Thomas and Stradner, Jürgen and Crailsheim, Karl and Thenius, Ronald and Kampis, Gyoergy and Szathmary, Eoers}}, booktitle = {{Advances in Artificial Life, 10th European Conference, ECAL 2009}}, pages = {{132----139}}, title = {{{Evolving a novel bio-inspired controller in reconfigurable robots}}}, year = {{2011}}, }