@inproceedings{507, abstract = {{We study two-party communication in the context of directed dynamic networks that are controlled by an adaptive adversary. This adversary is able to change all edges as long as the networks stay strongly-connected in each round. In this work, we establish a relation between counting the total number of nodes in the network and the problem of exchanging tokens between two communication partners which communicate through a dynamic network. We show that the communication problem for a constant fraction of n tokens in a dynamic network with n nodes is at most as hard as counting the number of nodes in a dynamic network with at most 4n+3 nodes. For the proof, we construct a family of directed dynamic networks and apply a lower bound from two-party communication complexity.}}, author = {{Abshoff, Sebastian and Benter, Markus and Malatyali, Manuel and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedings of the 17th International Conference on Principles of Distributed Systems (OPODIS)}}, pages = {{11--22}}, title = {{{On Two-Party Communication Through Dynamic Networks}}}, doi = {{10.1007/978-3-319-03850-6_2}}, year = {{2013}}, } @phdthesis{514, abstract = {{Diese Arbeit besch{\"a}ftigt sich mit dem Facility Location Problem. Dies ist ein Optimierungsproblem, bei dem festgelegt werden muss an welchen Positionen Ressourcen zur Verf{\"u}gung gestellt werden, so dass diese von Nutzern gut erreicht werden k{\"o}nnen. Es sollen dabei Kosten minimiert werden, die zum einen durch Bereitstellung von Ressourcen und zum anderen durch Verbindungskosten zwischen Nutzern und Ressourcen entstehen. Die Schwierigkeit des Problems liegt darin, dass man einerseits m{\"o}glichst wenige Ressourcen zur Verf{\"u}gung stellen m{\"o}chte, andererseits daf{\"u}r sorgen muss, dass sich Nutzer nicht all zu weit weg von Ressourcen befinden. Dies w{\"u}rde n{\"a}mlich hohe Verbindungskosten nach sich ziehen. Das Facility Location Problem wurde bereits sehr intensiv in vielen unterschiedlichen Varianten untersucht. In dieser Arbeit werden drei Varianten des Problems modelliert und neue Algorithmen f{\"u}r sie entwickelt und bez{\"u}glich ihres Approximationsfaktors und ihrer Laufzeit analysiert. Jede dieser drei untersuchten Varianten hat einen besonderen Schwerpunkt. Bei der ersten Varianten handelt es sich um ein Online Problem, da hier die Eingabe nicht von Anfang an bekannt ist, sondern Schritt f{\"u}r Schritt enth{\"u}llt wird. Die Schwierigkeit hierbei besteht darin unwiderrufliche Entscheidungen treffen zu m{\"u}ssen ohne dabei die Zukunft zu kennen und trotzdem eine zu jeder Zeit gute L{\"o}sung angeben zu k{\"o}nnen. Der Schwerpunkt der zweiten Variante liegt auf Lokalit{\"a}t, die z.B. in Sensornetzwerken von großer Bedeutung ist. Hier soll eine L{\"o}sung verteilt und nur mit Hilfe von lokalen Information berechnet werden. Schließlich besch{\"a}ftigt sich die dritte Variante mit einer verteilten Berechnung, bei welcher nur eine stark beschr{\"a}nkte Datenmenge verschickt werden darf und dabei trotzdem ein sehr guter Approximationsfaktor erreicht werden muss. Die bei der Analyse der Approximationsfaktoren bzw. der Kompetitivit{\"a}t verwendeten Techniken basieren zum großen Teil auf Absch{\"a}tzung der primalen L{\"o}sung mit Hilfe einer L{\"o}sung des zugeh{\"o}rigen dualen Problems. F{\"u}r die Modellierung von Lokalit{\"a}t wird das weitverbreitete LOCAL Modell verwendet. In diesem Modell werden f{\"u}r die Algorithmen subpolynomielle obere Laufzeitschranken gezeigt.}}, author = {{Pietrzyk, Peter}}, publisher = {{Universität Paderborn}}, title = {{{Local and Online Algorithms for Facility Location}}}, year = {{2013}}, } @unpublished{524, abstract = {{We study the complexity theory for the local distributed setting introduced by Korman, Peleg and Fraigniaud. They have defined three complexity classes LD (Local Decision), NLD (Nondeterministic Local Decision) and NLD^#n. The class LD consists of all languages which can be decided with a constant number of communication rounds. The class NLD consists of all languages which can be verified by a nondeterministic algorithm with a constant number of communication rounds. In order to define the nondeterministic classes, they have transferred the notation of nondeterminism into the distributed setting by the use of certificates and verifiers. The class NLD^#n consists of all languages which can be verified by a nondeterministic algorithm where each node has access to an oracle for the number of nodes. They have shown the hierarchy LD subset NLD subset NLD^#n. Our main contributions are strict hierarchies within the classes defined by Korman, Peleg and Fraigniaud. We define additional complexity classes: the class LD(t) consists of all languages which can be decided with at most t communication rounds. The class NLD-O(f) consists of all languages which can be verified by a local verifier such that the size of the certificates that are needed to verify the language are bounded by a function from O(f). Our main results are refined strict hierarchies within these nondeterministic classes.}}, author = {{Meyer auf der Heide, Friedhelm and Swirkot, Kamil}}, publisher = {{arXiv}}, title = {{{Hierarchies in Local Distributed Decision}}}, year = {{2013}}, } @proceedings{558, editor = {{Flocchini, Paola and Gao, Jie and Kranakis, Evangelos and Meyer auf der Heide, Friedhelm}}, location = {{Sophia Antipolis, France}}, publisher = {{Springer}}, title = {{{Algorithms for Sensor Systems - 9th International Symposium on Algorithms and Experiments for Sensor Systems, Wireless Networks and Distributed Robotics}}}, doi = {{10.1007/978-3-642-45346-5}}, volume = {{8243}}, year = {{2013}}, } @inproceedings{562, abstract = {{In Distributed Cloud Computing, applications are deployed across many data centres at topologically diverse locations to improved network-related quality of service (QoS). As we focus on interactive applications, we minimize the latency between users and an application by allocating Cloud resources nearby the customers. Allocating resources at all locations will result in the best latency but also in the highest expenses. So we need to find an optimal subset of locations which reduces the latency but also the expenses – the facility location problem (FLP). In addition, we consider resource capacity restrictions, as a resource can only serve a limited amount of users. An FLP can be globally solved. Additionally, we propose a local, distributed heuristic. This heuristic is running within the network and does not depend on a global component. No distributed, local approximations for the capacitated FLP have been proposed so far due to the complexity of the problem. We compared the heuristic with an optimal solution obtained from a mixed integer program for different network topologies. We investigated the influence of different parameters like overall resource utilization or different latency weights.}}, author = {{Keller, Matthias and Pawlik, Stefan and Pietrzyk, Peter and Karl, Holger}}, booktitle = {{Proceedings of the 6th International Conference on Utility and Cloud Computing (UCC) workshop on Distributed cloud computing}}, pages = {{429--434}}, title = {{{A Local Heuristic for Latency-Optimized Distributed Cloud Deployment}}}, doi = {{10.1109/UCC.2013.85}}, year = {{2013}}, } @inproceedings{563, abstract = {{Dominating set based virtual backbones are used for rou-ting in wireless ad-hoc networks. Such backbones receive and transmit messages from/to every node in the network. Existing distributed algorithms only consider undirected graphs, which model symmetric networks with uniform transmission ranges. We are particularly interested in the well-established disk graphs, which model asymmetric networks with non-uniform transmission ranges. The corresponding graph theoretic problem seeks a strongly connected dominating-absorbent set of minimum cardinality in a digraph. A subset of nodes in a digraph is a strongly connected dominating-absorbent set if the subgraph induced by these nodes is strongly connected and each node in the graph is either in the set or has both an in-neighbor and an out-neighbor in it. We introduce the first distributed algorithm for this problem in disk graphs. The algorithm gives an O(k^4) -approximation ratio and has a runtime bound of O(Diam) where Diam is the diameter of the graph and k denotes the transmission ratio r_{max}/r_{min} with r_{max} and r_{min} being the maximum and minimum transmission range, respectively. Moreover, we apply our algorithm on the subgraph of disk graphs consisting of only bidirectional edges. Our algorithm gives an O(ln k) -approximation and a runtime bound of O(k^8 log^∗ n) , which, for bounded k , is an optimal approximation for the problem, following Lenzen and Wattenhofer’s Ω(log^∗ n) runtime lower bound for distributed constant approximation in disk graphs.}}, author = {{Markarian, Christine and Meyer auf der Heide, Friedhelm and Schubert, Michael}}, booktitle = {{Proceedings of the 9th International Symposium on Algorithms and Experiments for Sensor Systems, Wireless Networks and Distributed Robotics (ALGOSENSORS)}}, pages = {{217--227}}, title = {{{A Distributed Approximation Algorithm for Strongly Connected Dominating-Absorbent Sets in Asymmetric Wireless Ad-Hoc Networks}}}, doi = {{10.1007/978-3-642-45346-5_16}}, year = {{2013}}, } @inproceedings{16393, abstract = {{Many 3D scenes (e.g. generated from CAD data) are composed of a multitude of objects that are nested in each other. A showroom, for instance, may contain multiple cars and every car has a gearbox with many gearwheels located inside. Because the objects occlude each other, only few are visible from outside. We present a new technique, Spherical Visibility Sampling (SVS), for real-time 3D rendering of such -- possibly highly complex -- scenes. SVS exploits the occlusion and annotates hierarchically structured objects with directional visibility information in a preprocessing step. For different directions, the directional visibility encodes which objects of a scene's region are visible from the outside of the regions' enclosing bounding sphere. Since there is no need to store a separate view space subdivision as in most techniques based on preprocessed visibility, a small memory footprint is achieved. Using the directional visibility information for an interactive walkthrough, the potentially visible objects can be retrieved very efficiently without the need for further visibility tests. Our evaluation shows that using SVS allows to preprocess complex 3D scenes fast and to visualize them in real time (e.g. a Power Plant model and five animated Boeing 777 models with billions of triangles). Because SVS does not require hardware support for occlusion culling during rendering, it is even applicable for rendering large scenes on mobile devices.}}, author = {{Eikel, Benjamin and Jähn, Claudius and Fischer, Matthias and Meyer auf der Heide, Friedhelm}}, booktitle = {{Computer Graphics Forum}}, issn = {{0167-7055}}, number = {{4}}, pages = {{49--58}}, title = {{{Spherical Visibility Sampling}}}, doi = {{10.1111/cgf.12150}}, volume = {{32}}, year = {{2013}}, } @inbook{16406, abstract = {{In order to evaluate the efficiency of algorithms for real-time 3D rendering, different properties like rendering time, occluded triangles, or image quality, need to be investigated. Since these properties depend on the position of the camera, usually some camera path is chosen, along which the measurements are performed. As those measurements cover only a small part of the scene, this approach hardly allows drawing conclusions regarding the algorithm's properties at arbitrary positions in the scene. The presented method allows the systematic and position-independent evaluation of rendering algorithms. It uses an adaptive sampling approach to approximate the distribution of a property (like rendering time) for all positions in the scene. This approximation can be visualized to produce an intuitive impression of the algorithm's behavior or be statistically analyzed for objectively rating and comparing algorithms. We demonstrate our method by evaluating performance aspects of a known occlusion culling algorithm. }}, author = {{Jähn, Claudius and Eikel, Benjamin and Fischer, Matthias and Petring, Ralf and Meyer auf der Heide, Friedhelm}}, booktitle = {{Advances in Visual Computing}}, isbn = {{9783642419133}}, issn = {{0302-9743}}, title = {{{Evaluation of Rendering Algorithms Using Position-Dependent Scene Properties}}}, doi = {{10.1007/978-3-642-41914-0_12}}, year = {{2013}}, } @inbook{16407, abstract = {{Many virtual 3D scenes, especially those that are large, are not structured evenly. For such heterogeneous data, there is no single algorithm that is able to render every scene type at each position fast and with the same high image quality. For a small set of scenes, this situation can be improved if different rendering algorithms are manually assigned to particular parts of the scene by an experienced user. We introduce the Multi-Algorithm-Rendering method. It automatically deploys different rendering algorithms simultaneously for a broad range of scene types. The method divides the scene into subregions and measures the behavior of different algorithms for each region in a preprocessing step. During runtime, this data is utilized to compute an estimate for the quality and running time of the available rendering algorithms from the observer's point of view. By solving an optimizing problem, the image quality can be optimized by an assignment of algorithms to regions while keeping the frame rate almost constant. }}, author = {{Petring, Ralf and Eikel, Benjamin and Jähn, Claudius and Fischer, Matthias and Meyer auf der Heide, Friedhelm}}, booktitle = {{Advances in Visual Computing}}, isbn = {{9783642419133}}, issn = {{0302-9743}}, title = {{{Real-Time 3D Rendering of Heterogeneous Scenes}}}, doi = {{10.1007/978-3-642-41914-0_44}}, year = {{2013}}, } @inproceedings{505, abstract = {{In this paper we introduce “On-The-Fly Computing”, our vision of future IT services that will be provided by assembling modular software components available on world-wide markets. After suitable components have been found, they are automatically integrated, configured and brought to execution in an On-The-Fly Compute Center. We envision that these future compute centers will continue to leverage three current trends in large scale computing which are an increasing amount of parallel processing, a trend to use heterogeneous computing resources, and—in the light of rising energy cost—energy-efficiency as a primary goal in the design and operation of computing systems. In this paper, we point out three research challenges and our current work in these areas.}}, author = {{Happe, Markus and Kling, Peter and Plessl, Christian and Platzner, Marco and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedings of the 9th IEEE Workshop on Software Technology for Future embedded and Ubiquitous Systems (SEUS)}}, publisher = {{IEEE}}, title = {{{On-The-Fly Computing: A Novel Paradigm for Individualized IT Services}}}, doi = {{10.1109/ISORC.2013.6913232}}, year = {{2013}}, } @inproceedings{1787, author = {{Suess, Tim and Schoenrock, Andrew and Meisner, Sebastian and Plessl, Christian}}, booktitle = {{Proc. Int. Symp. on Parallel and Distributed Processing Workshops (IPDPSW)}}, isbn = {{978-0-7695-4979-8}}, pages = {{64--73}}, publisher = {{IEEE Computer Society}}, title = {{{Parallel Macro Pipelining on the Intel SCC Many-Core Computer}}}, doi = {{10.1109/IPDPSW.2013.136}}, year = {{2013}}, } @inproceedings{20173, abstract = {{This paper investigates the properties required to evolve Artificial Neural Networks for distributed control in modular robotics, which typically involves non-linear dynamics and complex interactions in the sensori-motor space. We investigate the relation between macro-scale properties (such as modularity and regularity) and micro-scale properties in Neural Network controllers. We show how neurons capable of multiplicative-like arithmetic operations may increase the performance of controllers in several ways whenever challenging control problems with non-linear dynamics are involved. This paper provides evidence that performance and robustness of evolved controllers can be improved by a combination of carefully chosen micro- and macro-scale neural network properties.}}, author = {{Hamann, Heiko and Stradner, Jürgen and Bredeche, Nicolas and Cazenille, Leo}}, booktitle = {{14th Annual Genetic and Evolutionary Computation Conference, GECCO 2012}}, pages = {{89--96}}, publisher = {{ACM}}, title = {{{Impact of Neuron Models and Network Structure on Evolving Modular Robot Neural Network Controllers}}}, doi = {{10.1145/2330163.2330177}}, year = {{2012}}, } @inproceedings{20174, abstract = {{As a contribution to the efforts towards robotic systems of higher flexibility we present our concept of morphologically dynamic robots. Within the projects SYMBRION and REPLICATOR, that focus on modular robotics, we have developed bio-inspired control techniques to achieve new concepts of dynamic, autonomous morphological structures. We propose three modes of coupling between robot modules: swarm, team, and organism mode. We demonstrate our concepts along with simple robot experiments.}}, author = {{Hamann, Heiko and Schmickl, Thomas and Stradner, Jürgen}}, booktitle = {{Austrian Robotics Workshop (Operational Programme Slovenia-Austria)}}, title = {{{Towards Morphological Flexibility: Modular Robotics and Bio-inspired Control}}}, year = {{2012}}, } @inproceedings{20175, author = {{Hamann, Heiko and Schmickl, Thomas and Stradner, Jürgen and Crailsheim, Karl and Zahadat, Payam and Adami, Christoph and Bryson, David M. and Ofria, Charles and Pennock, Robert T.}}, booktitle = {{Alife XIII}}, pages = {{597--598}}, publisher = {{MIT Press}}, title = {{{On-line, On-board Evolution of Reaction-Diffusion Control for Self-Adaptation}}}, year = {{2012}}, } @article{20176, author = {{Hamann, Heiko and Schmickl, Thomas and Crailsheim, Karl}}, issn = {{1387-3954}}, journal = {{Mathematical and Computer Modelling of Dynamical Systems}}, number = {{1}}, pages = {{39--50}}, title = {{{Self-organized pattern formation in a swarm system as a transient phenomenon of non-linear dynamics}}}, doi = {{10.1080/13873954.2011.601418}}, volume = {{18}}, year = {{2012}}, } @article{20177, abstract = {{One of the main challenges in automatic controller synthesis is to develop methods that can successfully be applied for complex tasks. The difficulty is increased even more in the case of settings with multiple interacting agents. We apply the artificial homeostatic hormone system (AHHS) approach, which is inspired by the signaling network of unicellular organisms, to control a system of several independently acting agents decentrally. The approach is designed for evaluation-minimal, artificial evolution in order to be applicable to complex modular robotics scenarios. The performance of AHHS controllers is compared with neuroevolution of augmenting topologies (NEAT) in the coupled inverted pendulums benchmark. AHHS controllers are found to be better for multimodular settings. We analyze the evolved controllers with regard to the usage of sensory inputs and the emerging oscillations, and we give a nonlinear dynamics interpretation. The generalization of evolved controllers to initial conditions far from the original conditions is investigated and found to be good. Similarly, the performance of controllers scales well even with module numbers different from the original domain the controller was evolved for. Two reference implementations of a similar controller approach are reported and shown to have shortcomings. We discuss the related work and conclude by summarizing the main contributions of our work.}}, author = {{Hamann, Heiko and Schmickl, Thomas and Crailsheim, Karl}}, issn = {{1064-5462}}, journal = {{Artificial Life}}, number = {{2}}, pages = {{165--198}}, title = {{{A Hormone-Based Controller for Evaluation-Minimal Evolution in Decentrally Controlled Systems}}}, doi = {{10.1162/artl_a_00058}}, volume = {{18}}, year = {{2012}}, } @article{20178, author = {{Hamann, Heiko and Schmickl, Thomas and Wörn, Heinz and Crailsheim, Karl}}, issn = {{0941-0643}}, journal = {{Neural Computing and Applications}}, number = {{2}}, pages = {{207--218}}, title = {{{Analysis of emergent symmetry breaking in collective decision making}}}, doi = {{10.1007/s00521-010-0368-6}}, volume = {{21}}, year = {{2012}}, } @inproceedings{20179, author = {{Hamann, Heiko and Engelbrecht, Andreas and Birattari, Mauro and Dorigo, Marco and Blum, Christian and Stuetzle, Thomas and Christensen, Anders Lyhne and Gross, Roderich}}, booktitle = {{Swarm Intelligence: 8th International Conference, ANTS 2012}}, isbn = {{9783642326493}}, issn = {{0302-9743}}, pages = {{168--179}}, publisher = {{Springer}}, title = {{{Towards Swarm Calculus: Universal Properties of Swarm Performance and Collective Decisions}}}, doi = {{10.1007/978-3-642-32650-9_15}}, volume = {{7461}}, year = {{2012}}, } @inproceedings{17664, author = {{Cohen, Reuven and Nudelman, Ilia and Polevoy, Gleb}}, booktitle = {{Infocom'2012, Orlando, Florida}}, title = {{{On the Admission of Dependent Flows in Powerful Sensor Networks}}}, year = {{2012}}, } @article{579, abstract = {{A left-to-right maximum in a sequence of n numbers s_1, …, s_n is a number that is strictly larger than all preceding numbers. In this article we present a smoothed analysis of the number of left-to-right maxima in the presence of additive random noise. We show that for every sequence of n numbers s_i ∈ [0,1] that are perturbed by uniform noise from the interval [-ε,ε], the expected number of left-to-right maxima is Θ(&sqrt;n/ε + log n) for ε>1/n. For Gaussian noise with standard deviation σ we obtain a bound of O((log3/2 n)/σ + log n).We apply our results to the analysis of the smoothed height of binary search trees and the smoothed number of comparisons in the quicksort algorithm and prove bounds of Θ(&sqrt;n/ε + log n) and Θ(n/ε+1&sqrt;n/ε + n log n), respectively, for uniform random noise from the interval [-ε,ε]. Our results can also be applied to bound the smoothed number of points on a convex hull of points in the two-dimensional plane and to smoothed motion complexity, a concept we describe in this article. We bound how often one needs to update a data structure storing the smallest axis-aligned box enclosing a set of points moving in d-dimensional space.}}, author = {{Damerow, Valentina and Manthey, Bodo and Meyer auf der Heide, Friedhelm and Räcke, Harald and Scheideler, Christian and Sohler, Christian and Tantau, Till}}, journal = {{Transactions on Algorithms}}, number = {{3}}, pages = {{30}}, publisher = {{ACM}}, title = {{{Smoothed analysis of left-to-right maxima with applications}}}, doi = {{10.1145/2229163.2229174}}, year = {{2012}}, }