TY - CONF
AB - We investigate a non-cooperative game-theoretic model for the formation of communication networks by selfish agents. Each agent aims for a central position at minimum cost for creating edges. In particular, the general model (Fabrikant et al., PODC'03) became popular for studying the structure of the Internet or social networks. Despite its significance, locality in this game was first studied only recently (Bilò et al., SPAA'14), where a worst case locality model was presented, which came with a high efficiency loss in terms of quality of equilibria. Our main contribution is a new and more optimistic view on locality: agents are limited in their knowledge and actions to their local view ranges, but can probe different strategies and finally choose the best. We study the influence of our locality notion on the hardness of computing best responses, convergence to equilibria, and quality of equilibria. Moreover, we compare the strength of local versus non-local strategy changes. Our results address the gap between the original model and the worst case locality variant. On the bright side, our efficiency results are in line with observations from the original model, yet we have a non-constant lower bound on the Price of Anarchy.
AU - Cord-Landwehr, Andreas
AU - Lenzner, Pascal
ID - 275
T2 - Proceedings of the 40th Conference on Mathematical Foundations of Computer Science (MFCS)
TI - Network Creation Games: Think Global - Act Local
ER -
TY - THES
AU - Abshoff, Sebastian
ID - 270
TI - On the Complexity of Fundamental Problems in Dynamic Ad-hoc Networks
ER -
TY - CONF
AB - Besides the life-as-it-could-be driver of artificial life research there is also the concept of extending natural life by creating hybrids or mixed societies that are built from natural and artificial components. In this paper we motivate and present the research program of the project flora robotica. Our objective is to develop and to investigate closely linked symbiotic relationships between robots and natural plants and to explore the potentials of a plant-robot society able to produce architectural artifacts and living spaces. These robot-plant bio-hybrids create synergies that allow for new functions of plants and robots. They also create novel design opportunities for an architecture that fuses the design and construction phase. The bio-hybrid is an example of mixed societies between 'hard' artificial and 'wet' natural life, which enables an interaction between natural and artificial ecologies. They form an embodied, self-organizing, and distributed cognitive system which is supposed to grow and develop over long periods of time resulting in the creation of meaningful architectural structures. A key idea is to assign equal roles to robots and plants in order to create a highly integrated, symbiotic system. Besides the gain of knowledge, this project has the objective to create a bio-hybrid system with a defined function and application -- growing architectural artifacts.
AU - Hamann, Heiko
AU - Wahby, Mostafa
AU - Schmickl, Thomas
AU - Zahadat, Payam
AU - Hofstadler, Daniel
AU - Stoy, Kasper
AU - Risi, Sebastian
AU - Faina, Andres
AU - Veenstra, Frank
AU - Kernbach, Serge
AU - Kuksin, Igor
AU - Kernbach, Olga
AU - Ayres, Phil
AU - Wojtaszek, Przemyslaw
ID - 19960
SN - 9781479975600
T2 - Proceedings of the 2015 IEEE Symposium on Artificial Life (IEEE ALIFE'15)
TI - Flora Robotica - Mixed Societies of Symbiotic Robot-Plant Bio-Hybrids
ER -
TY - CHAP
AU - Hamann, Heiko
AU - Correll, Nikolaus
AU - Kacprzyk, Janusz
AU - Pedrycz, Witold
ID - 19989
T2 - Springer Handbook of Computational Intelligence
TI - Probabilistic Modeling of Swarming Systems
ER -
TY - CONF
AU - Hamann, Heiko
AU - Schmickl, Thomas
AU - Kengyel, Daniela
AU - Zahadat, Payam
AU - Radspieler, Gerald
AU - Wotawa, Franz
ID - 19991
T2 - Principles and Practice of Multi-Agent Systems (PRIMA 2015)
TI - Potential of Heterogeneity in Collective Behaviors: A Case Study on Heterogeneous Swarms
ER -
TY - CONF
AU - Dorigo, Marco
AU - Hamann, Heiko
AU - Valentini, Gabriele
ID - 20006
T2 - AAAI-15 Video Proceedings
TI - Self-organized collective decisions in a robot swarm
ER -
TY - CONF
AB - We consider online leasing problems in which demands arrive over time and need to be served by leasing resources. We introduce a new model for these problems such that a resource can be leased for K different durations each incurring a different cost (longer leases cost less per time unit). Each demand i can be served anytime between its arrival ai and its deadline ai+di by a leased resource. The objective is to meet all deadlines while minimizing the total leasing costs. This model is a natural generalization of Meyerson’s ParkingPermitProblem (FOCS 2005) in which di=0 for all i. We propose an online algorithm that is Θ(K+dmaxlmin)-competitive where dmax and lmin denote the largest di and the shortest available lease length, respectively. We also extend the SetCoverLeasing problem by deadlines and give a competitive online algorithm which also improves on existing solutions for the original SetCoverLeasing problem.
AU - Li, Shouwei
AU - Mäcker, Alexander
AU - Markarian, Christine
AU - Meyer auf der Heide, Friedhelm
AU - Riechers, Sören
ID - 240
T2 - Proceedings of the 21st Annual International Computing and Combinatorics Conference (COCOON)
TI - Towards Flexible Demands in Online Leasing Problems
ER -
TY - CONF
AB - In \emph{bandwidth allocation games} (BAGs), the strategy of a player consists of various demands on different resources. The player's utility is at most the sum of these demands, provided they are fully satisfied. Every resource has a limited capacity and if it is exceeded by the total demand, it has to be split between the players. Since these games generally do not have pure Nash equilibria, we consider approximate pure Nash equilibria, in which no player can improve her utility by more than some fixed factor $\alpha$ through unilateral strategy changes. There is a threshold $\alpha_\delta$ (where $\delta$ is a parameter that limits the demand of each player on a specific resource) such that $\alpha$-approximate pure Nash equilibria always exist for $\alpha \geq \alpha_\delta$, but not for $\alpha < \alpha_\delta$. We give both upper and lower bounds on this threshold $\alpha_\delta$ and show that the corresponding decision problem is ${\sf NP}$-hard. We also show that the $\alpha$-approximate price of anarchy for BAGs is $\alpha+1$. For a restricted version of the game, where demands of players only differ slightly from each other (e.g. symmetric games), we show that approximate Nash equilibria can be reached (and thus also be computed) in polynomial time using the best-response dynamic. Finally, we show that a broader class of utility-maximization games (which includes BAGs) converges quickly towards states whose social welfare is close to the optimum.
AU - Drees, Maximilian
AU - Feldotto, Matthias
AU - Riechers, Sören
AU - Skopalik, Alexander
ID - 271
T2 - Proceedings of the 8th International Symposium on Algorithmic Game Theory (SAGT)
TI - On Existence and Properties of Approximate Pure Nash Equilibria in Bandwidth Allocation Games
ER -
TY - CONF
AU - Jähn, Claudius
AU - Fischer, Matthias
AU - Gerges, Maria
AU - Berssenbrügge, Jan
ID - 17427
T2 - 12. Paderborner Workshop Augmented & Virtual Reality in der Produktentstehung
TI - Automatische Ableitung geometrischer Eigenschaften von Bauteilen aus dem 3-D-Polygonmodell
VL - 342
ER -
TY - CONF
AU - Wahby, Mostafa
AU - Hamann, Heiko
ID - 19959
T2 - Applications of Evolutionary Computation (EvoApplications 2015)
TI - On the Tradeoff between Hardware Protection and Optimization Success: A Case Study in Onboard Evolutionary Robotics for Autonomous Parallel Parking
ER -
TY - CONF
AB - Aggregation is a crucial task in swarm robotics to ensure cooperation. We investigate the task of aggregation on an area specified indirectly by certain environmental features, here it is a light distribution. We extend the original BEECLUST algorithm, that implements an aggregation behavior, to an adaptive variant that automatically adapts to any light conditions. We compare these two control algorithms in a number of swarm robot experiments with different light conditions. The improved, adaptive variant is found to be significantly better in the tested setup.
AU - Wahby, Mostafa
AU - Weinhold, Alexander
AU - Hamann, Heiko
ID - 19966
SN - 9781631901003
T2 - Proceedings of the 9th EAI International Conference on Bio-inspired Information and Communications Technologies (formerly BIONETICS)
TI - Revisiting BEECLUST: Aggregation of Swarm Robots with Adaptiveness to Different Light Settings
ER -
TY - CONF
AB - Fitness function design is known to be a critical feature of the evolutionary-robotics approach. Potentially, the complexity of evolving a successful controller for a given task can be reduced by integrating a priori knowledge into the fitness function which complicates the comparability of studies in evolutionary robotics. Still, there are only few publications that study the actual effects of different fitness functions on the robot's performance. In this paper, we follow the fitness function classification of Nelson et al. (2009) and investigate a selection of four classes of fitness functions that require different degrees of a priori knowledge. The robot controllers are evolved in simulation using NEAT and we investigate different tasks including obstacle avoidance and (periodic) goal homing. The best evolved controllers were then post-evaluated by examining their potential for adaptation, determining their convergence rates, and using cross-comparisons based on the different fitness function classes. The results confirm that the integration of more a priori knowledge can simplify a task and show that more attention should be paid to fitness function classes when comparing different studies.
AU - Hamann, Heiko
AU - Divband Soorati, Mohammad
ID - 19980
T2 - Proceedings of the Genetic and Evolutionary Computation Conference (GECCO 2015)
TI - The Effect of Fitness Function Design on Performance in Evolutionary Robotics: The Influence of a Priori Knowledge
ER -
TY - GEN
AB - In the gathering problem, n autonomous robots have to meet on a single point.
We consider the gathering of a closed chain of point-shaped, anonymous robots
on a grid. The robots only have local knowledge about a constant number of
neighboring robots along the chain in both directions. Actions are performed in
the fully synchronous time model FSYNC. Every robot has a limited memory that
may contain one timestamp of the global clock, also visible to its direct
neighbors. In this synchronous time model, there is no limited view gathering
algorithm known to perform better than in quadratic runtime. The configurations
that show the quadratic lower bound are closed chains. In this paper, we
present the first sub-quadratic---in fact linear time---gathering algorithm for
closed chains on a grid.
AU - Abshoff, Sebastian
AU - Andreas Cord-Landwehr, Andreas
AU - Jung, Daniel
AU - Meyer auf der Heide, Friedhelm
ID - 16397
T2 - ArXiv: 1501.04877
TI - Towards Gathering Robots with Limited View in Linear Time: The Closed Chain Case
ER -
TY - JOUR
AU - Valentini, Gabriele
AU - Hamann, Heiko
ID - 19992
JF - Swarm Intelligence
SN - 1935-3812
TI - Time-variant feedback processes in collective decision-making systems: influence and effect of dynamic neighborhood sizes
ER -
TY - GEN
AU - Pautz, Jannis
ID - 316
TI - Budget Games with priced strategies
ER -
TY - GEN
AU - Kothe, Nils
ID - 277
TI - Multilevel Netzwerk Spiele mit konstanten Entfernungen im Highspeed-Netzwerk
ER -
TY - JOUR
AB - Recent approaches in evolutionary robotics (ER) propose to generate behavioral diversity in order to evolve desired behaviors more easily. These approaches require the definition of a behavioral distance, which often includes task-specific features and hence a priori knowledge. Alternative methods, which do not explicitly force selective pressure towards diversity (SPTD) but still generate it, are known from the field of artificial life, such as in artificial ecologies (AEs). In this study, we investigate how SPTD is generated without task-specific behavioral features or other forms of a priori knowledge and detect how methods of generating SPTD can be transferred from the domain of AE to ER. A promising finding is that in both types of systems, in systems from ER that generate behavioral diversity and also in the investigated speciation model, selective pressure is generated towards unpopulated regions of search space. In a simple case study we investigate the practical implications of these findings and point to options for transferring the idea of self-organizing SPTD in AEs to the domain of ER.
AU - Hamann, Heiko
ID - 19962
JF - Artificial Life
SN - 1064-5462
TI - Lessons from Speciation Dynamics: How to Generate Selective Pressure Towards Diversity
ER -
TY - CONF
AU - Wahby, Mostafa
AU - Divband Soorati, Mohammad
AU - von Mammen, Sebastian
AU - Hamann, Heiko
ID - 19967
T2 - Proceedings. 25. Computational Intelligence Workshop
TI - Evolution of Controllers for Robot-Plant Bio-Hybdrids: A Simple Case Study Using a Model of Plant Growth and Motion
ER -
TY - GEN
AB - We consider the following variant of the two dimensional gathering problem
for swarms of robots: Given a swarm of $n$ indistinguishable, point shaped
robots on a two dimensional grid. Initially, the robots form a closed chain on
the grid and must keep this connectivity during the whole process of their
gathering. Connectivity means, that neighboring robots of the chain need to be
positioned at the same or neighboring points of the grid. In our model,
gathering means to keep shortening the chain until the robots are located
inside a $2\times 2$ subgrid. Our model is completely local (no global control,
no global coordinates, no compass, no global communication or vision, \ldots).
Each robot can only see its next constant number of left and right neighbors on
the chain. This fixed constant is called the \emph{viewing path length}. All
its operations and detections are restricted to this constant number of robots.
Other robots, even if located at neighboring or the same grid point cannot be
detected. Only based on the relative positions of its detectable chain
neighbors, a robot can decide to obtain a certain state. Based on this state
and their local knowledge, the robots do local modifications to the chain by
moving to neighboring grid points without breaking the chain. These
modifications are performed without the knowledge whether they lead to a global
progress or not. We assume the fully synchronous $\mathcal{FSYNC}$ model. For
this problem, we present a gathering algorithm which needs linear time. This
result generalizes the result from \cite{hopper}, where an open chain with
specified distinguishable (and fixed) endpoints is considered.
AU - Abshoff, Sebastian
AU - Cord-Landwehr, Andreas
AU - Fischer, Matthias
AU - Jung, Daniel
AU - Meyer auf der Heide, Friedhelm
ID - 16449
T2 - arXiv:1510.05454
TI - Gathering a Closed Chain of Robots on a Grid
ER -
TY - GEN
AB - We consider the problem of dominating set-based virtual backbone used for
routing in asymmetric wireless ad-hoc networks. These networks have non-uniform
transmission ranges and are modeled using the well-established disk graphs. 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.
Distributed algorithms for this problem are of practical significance due to
the dynamic nature of ad-hoc networks. We present a first distributed
approximation algorithm, with a constant approximation factor and O(Diam)
running time, where Diam is the diameter of the graph. Moreover we present a
simple heuristic algorithm and conduct an extensive simulation study showing
that our heuristic outperforms previously known approaches for the problem.
AU - Abu-Khzam, Faisal N.
AU - Markarian, Christine
AU - Meyer auf der Heide, Friedhelm
AU - Schubert, Michael
ID - 16452
T2 - arXiv:1510.01866
TI - Approximation and Heuristic Algorithms for Computing Backbones in Asymmetric Ad-Hoc Networks
ER -
TY - THES
AU - Jähn, Claudius
ID - 317
TI - Bewertung von Renderingalgorithmen für komplexe 3-D-Szenen
ER -
TY - CONF
AB - Many markets have seen a shift from the idea of buying and moved to leasing instead. Arguably, the latter has been the major catalyst for their success. Ten years ago, research realized this shift and initiated the study of "online leasing problems" by introducing leasing to online optimization problems. Resources required to provide a service in an "online leasing problem" are no more bought but leased for different durations. In this paper, we provide an overview of results that contribute to the understanding of "online resource leasing problems".
AU - Markarian, Christine
AU - Meyer auf der Heide, Friedhelm
ID - 266
T2 - Proceedings of the 2015 ACM Symposium on Principles of Distributed Computing (PODC)
TI - Online Resource Leasing
ER -
TY - BOOK
ED - Gausemeier, Jürgen
ED - Grafe, Michael
ED - Meyer auf der Heide, Friedhelm
ID - 17431
TI - Augmented & Virtual Reality in der Produktentstehung: Grundlagen, Methoden und Werkzeuge; Interaktions- und Visualisierungstechniken, Virtual Prototyping intelligenter technischer Systeme mit AR/VR
VL - 342
ER -
TY - JOUR
AB - Inter-datacenter transfers of non-interactive but timely large flows over a private (managed) network is an important problem faced by many cloud service providers. The considered flows are non-interactive because they do not explicitly target the end users. However, most of them must be performed on a timely basis and are associated with a deadline. We propose to schedule these flows by a centralized controller, which determines when to transmit each flow and which path to use. Two scheduling models are presented in this paper. In the first, the controller also determines the rate of each flow, while in the second bandwidth is assigned by the network according to the TCP rules. We develop scheduling algorithms for both models and compare their complexity and performance.
AU - Cohen, R.
AU - Polevoy, Gleb
ID - 17657
IS - 99
JF - Cloud Computing, IEEE Transactions on
KW - Approximation algorithms
KW - Approximation methods
KW - Bandwidth
KW - Cloud computing
KW - Routing
KW - Schedules
KW - Scheduling
SN - 2168-7161
TI - Inter-Datacenter Scheduling of Large Data Flows
VL - PP
ER -
TY - CONF
AB - Consider the problem in which n jobs that are classified into k types are to be scheduled on m identical machines without preemption. A machine requires a proper setup taking s time units before processing jobs of a given type. The objective is to minimize the makespan of the resulting schedule. We design and analyze an approximation algorithm that runs in time polynomial in n,m and k and computes a solution with an approximation factor that can be made arbitrarily close to 3/2.
AU - Mäcker, Alexander
AU - Malatyali, Manuel
AU - Meyer auf der Heide, Friedhelm
AU - Riechers, Sören
ED - Dehne, Frank
ED - Sack, Jörg Rüdiger
ED - Stege, Ulrike
ID - 274
T2 - Algorithms and Data Structures: 14th International Symposium, WADS 2015, Victoria, BC, Canada, August 5-7, 2015. Proceedings
TI - Non-preemptive Scheduling on Machines with Setup Times
ER -
TY - THES
AU - Markarian, Christine
ID - 267
TI - Online Resource Leasing
ER -
TY - JOUR
AB - We consider structural and algorithmic questions related to the Nash dynamics of weighted congestion games. In weighted congestion games with linear latency functions, the existence of pure Nash equilibria is guaranteed by a potential function argument. Unfortunately, this proof of existence is inefficient and computing pure Nash equilibria in such games is a PLS-hard problem even when all players have unit weights. The situation gets worse when superlinear (e.g., quadratic) latency functions come into play; in this case, the Nash dynamics of the game may contain cycles and pure Nash equilibria may not even exist. Given these obstacles, we consider approximate pure Nash equilibria as alternative solution concepts. A ρ--approximate pure Nash equilibrium is a state of a (weighted congestion) game from which no player has any incentive to deviate in order to improve her cost by a multiplicative factor higher than ρ. Do such equilibria exist for small values of ρ? And if so, can we compute them efficiently?We provide positive answers to both questions for weighted congestion games with polynomial latency functions by exploiting an “approximation” of such games by a new class of potential games that we call Ψ-games. This allows us to show that these games have d!-approximate pure Nash equilibria, where d is the maximum degree of the latency functions. Our main technical contribution is an efficient algorithm for computing O(1)-approximate pure Nash equilibria when d is a constant. For games with linear latency functions, the approximation guarantee is 3+√5/2 + Oγ for arbitrarily small γ > 0; for latency functions with maximum degree d≥ 2, it is d2d+o(d). The running time is polynomial in the number of bits in the representation of the game and 1/γ. As a byproduct of our techniques, we also show the following interesting structural statement for weighted congestion games with polynomial latency functions of maximum degree d ≥ 2: polynomially-long sequences of best-response moves from any initial state to a dO(d2)-approximate pure Nash equilibrium exist and can be efficiently identified in such games as long as d is a constant.To the best of our knowledge, these are the first positive algorithmic results for approximate pure Nash equilibria in weighted congestion games. Our techniques significantly extend our recent work on unweighted congestion games through the use of Ψ-games. The concept of approximating nonpotential games by potential ones is interesting in itself and might have further applications.
AU - Caragiannis, Ioannis
AU - Fanelli, Angelo
AU - Gravin, Nick
AU - Skopalik, Alexander
ID - 320
IS - 1
JF - Transactions on Economics and Computation
TI - Approximate Pure Nash Equilibria in Weighted Congestion Games: Existence, Efficient Computation, and Structure
VL - 3
ER -
TY - CONF
AU - Berssenbrügge, Jan
AU - Wiederkehr, Olga
AU - Jähn, Claudius
AU - Fischer, Matthias
ID - 17425
T2 - 12. Paderborner Workshop Augmented & Virtual Reality in der Produktentstehung
TI - Anbindung des Virtuellen Prototypen an die Partialmodelle intelligenter technischer Systeme
VL - 343
ER -
TY - CONF
AB - Consider n nodes connected to a single coordinator. Each node receives an
individual online data stream of numbers and, at any point in time, the
coordinator has to know the k nodes currently observing the largest values, for
a given k between 1 and n. We design and analyze an algorithm that solves this
problem while bounding the amount of messages exchanged between the nodes and
the coordinator. Our algorithm employs the idea of using filters which,
intuitively speaking, leads to few messages to be sent, if the new input is
"similar" to the previous ones. The algorithm uses a number of messages that is
on expectation by a factor of O((log {\Delta} + k) log n) larger than that of
an offline algorithm that sets filters in an optimal way, where {\Delta} is
upper bounded by the largest value observed by any node.
AU - Mäcker, Alexander
AU - Malatyali, Manuel
AU - Meyer auf der Heide, Friedhelm
ID - 16460
T2 - Proceedings of the 29th International Parallel and Distributed Processing Symposium (IPDPS)
TI - Online Top-k-Position Monitoring of Distributed Data Streams
ER -
TY - CONF
AU - Hamann, Heiko
AU - Schmickl, Thomas
AU - Zahadat, Payam
ID - 19988
T2 - 13th European Conference on Artificial Life (ECAL 2015)
TI - Evolving Collective Behaviors With Diverse But Predictable Sensor States
ER -
TY - CONF
AU - Ding, Hongli
AU - Hamann, Heiko
ID - 19990
T2 - First International Symposium on Swarm Behavior and Bio-Inspired Robotics (SWARM 2015)
TI - Dependability in Swarm Robotics: Error Detection and Correction
ER -
TY - CONF
AU - Dorigo, Marco
AU - Hamann, Heiko
AU - Valentini, Gabriele
ID - 20005
T2 - Proceedings of the 14th Int. Conf. on Autonomous Agents and Multiagent Systems (AAMAS 2015)
TI - Efficient Decision-Making in a Self-Organizing Robot Swarm: On the Speed Versus Accuracy Trade-Off
ER -
TY - JOUR
AB - Abstract We study the problem of bandwidth allocation with multiple interferences. In this problem the input consists of a set of users and a set of base stations. Each user has a list of requests, each consisting of a base station, a frequency demand, and a profit that may be gained by scheduling this request. The goal is to find a maximum profit set of user requests S that satisfies the following conditions: (i) S contains at most one request per user, (ii) the frequency sets allotted to requests in S that correspond to the same base station are pairwise non-intersecting, and (iii) the QoS received by any user at any frequency is reasonable according to an interference model. In this paper we consider two variants of bandwidth allocation with multiple interferences. In the first each request specifies a demand that can be satisfied by any subset of frequencies that is large enough. In the second each request specifies a specific frequency interval. Furthermore, we consider two interference models, multiplicative and additive. We show that these problems are extremely hard to approximate if the interferences depend on both the interfered and the interfering base stations. On the other hand, we provide constant factor approximation algorithms for both variants of bandwidth allocation with multiple interferences for the case where the interferences depend only on the interfering base stations. We also consider a restrictive special case that is closely related to the Knapsack problem. We show that this special case is NP-hard and that it admits an FPTAS.
AU - Bar-Yehuda, Reuven
AU - Polevoy, Gleb
AU - Rawitz, Dror
ID - 17658
JF - Discrete Applied Mathematics
KW - Local ratio
SN - 0166-218X
TI - Bandwidth allocation in cellular networks with multiple interferences
VL - 194
ER -
TY - CONF
AB - In this paper we study the potential function in congestion games. We consider both games with non-decreasing cost functions as well as games with non-increasing utility functions. We show that the value of the potential function $\Phi(\sf s)$ of any outcome $\sf s$ of a congestion game approximates the optimum potential value $\Phi(\sf s^*)$ by a factor $\Psi_{\mathcal{F}}$ which only depends on the set of cost/utility functions $\mathcal{F}$, and an additive term which is bounded by the sum of the total possible improvements of the players in the outcome $\sf s$. The significance of this result is twofold. On the one hand it provides \emph{Price-of-Anarchy}-like results with respect to the potential function. On the other hand, we show that these approximations can be used to compute $(1+\varepsilon)\cdot\Psi_{\mathcal{F}}$-approximate pure Nash equilibria for congestion games with non-decreasing cost functions. For the special case of polynomial cost functions, this significantly improves the guarantees from Caragiannis et al. [FOCS 2011]. Moreover, our machinery provides the first guarantees for general latency functions.
AU - Feldotto, Matthias
AU - Gairing, Martin
AU - Skopalik, Alexander
ID - 453
T2 - Proceedings of the 10th International Conference on Web and Internet Economics (WINE)
TI - Bounding the Potential Function in Congestion Games and Approximate Pure Nash Equilibria
ER -
TY - CONF
AB - Collective decision making in self-organized systems is challenging because it relies on local perception and local communication. Globally defined qualities such as consensus time and decision accuracy are both difficult to predict and difficult to guarantee. We present the weighted voter model which implements a self-organized collective decision making process. We provide an ODE model, a master equation model (numerically solved by the Gillespie algorithm), and agent-based simulations of the proposed decision-making strategy. This set of models enables us to investigate the system behavior in the thermodynamic limit and to investigate finite-size effects due to random fluctuations. Based on our results, we give minimum requirements to guarantee consensus on the optimal decision, a minimum swarm size to guarantee a certain accuracy, and we show that the proposed approach scales with system size and is robust to noise.
AU - Dorigo, Marco
AU - Hamann, Heiko
AU - Valentini, Gabriele
AU - Lomuscio, Alessio
AU - Scerri, Paul
AU - Bazzan, Ana
AU - Huhns, Michael
ID - 20121
T2 - Proceedings of the 13th Int. Conf. on Autonomous Agents and Multiagent Systems (AAMAS 2014)
TI - Self-Organized Collective Decision Making: The Weighted Voter Model
ER -
TY - CONF
AU - Hamann, Heiko
ID - 20126
T2 - Int. Conf. on Genetic and Evolutionary Computation (GECCO 2014)
TI - Evolving Prediction Machines: Collective Behaviors Based on Minimal Surprisal
ER -
TY - CONF
AU - King, Thomas C.
AU - Liu, Qingzhi
AU - Polevoy, Gleb
AU - de Weerdt, Mathijs
AU - Dignum, Virginia
AU - van Riemsdijk, M. Birna
AU - Warnier, Martijn
ID - 17661
KW - crowd-sensing
KW - crowdsourcing
KW - data aggregation
KW - game theory
KW - norms
KW - reciprocation
KW - self interested agents
KW - simulation
SN - 978-1-4503-2738-1
T2 - Proceedings of the 2014 International Conference on Autonomous Agents and Multi-agent Systems
TI - Request Driven Social Sensing
ER -
TY - CONF
AU - Polevoy, Gleb
AU - Trajanovski, Stojan
AU - de Weerdt, Mathijs M.
ID - 17659
KW - competition
KW - equilibrium
KW - market
KW - models
KW - shared effort games
KW - simulation
SN - 978-1-4503-2738-1
T2 - Proceedings of the 2014 International Conference on Autonomous Agents and Multi-agent Systems
TI - Nash Equilibria in Shared Effort Games
ER -
TY - CONF
AB - We consider a multilevel network game, where nodes can improvetheir communication costs by connecting to a high-speed network.The n nodes are connected by a static network and each node can decideindividually to become a gateway to the high-speed network. The goalof a node v is to minimize its private costs, i.e., the sum (SUM-game) ormaximum (MAX-game) of communication distances from v to all othernodes plus a fixed price α > 0 if it decides to be a gateway. Between gatewaysthe communication distance is 0, and gateways also improve othernodes’ distances by behaving as shortcuts. For the SUM-game, we showthat for α ≤ n − 1, the price of anarchy is Θ (n/√α) and in this rangeequilibria always exist. In range α ∈ (n−1, n(n−1)) the price of anarchyis Θ(√α), and for α ≥ n(n − 1) it is constant. For the MAX-game, weshow that the price of anarchy is either Θ (1 + n/√α), for α ≥ 1, orelse 1. Given a graph with girth of at least 4α, equilibria always exist.Concerning the dynamics, both games are not potential games. For theSUM-game, we even show that it is not weakly acyclic.
AU - Abshoff, Sebastian
AU - Cord-Landwehr, Andreas
AU - Jung, Daniel
AU - Skopalik, Alexander
ID - 395
T2 - Proceedings of the 10th International Conference on Web and Internet Economics (WINE)
TI - Multilevel Network Games
ER -
TY - CONF
AB - We give a polynomial time algorithm to compute an optimal energy and fractional weighted flow trade-off schedule for a speed-scalable processor with discrete speeds.Our algorithm uses a geometric approach that is based on structural properties obtained from a primal-dual formulation of the problem.
AU - Antoniadis, Antonios
AU - Barcelo, Neal
AU - Consuegra, Mario
AU - Kling, Peer
AU - Nugent, Michael
AU - Pruhs, Kirk
AU - Scquizzato, Michele
ID - 435
T2 - Proceedings of the 31st Symposium on Theoretical Aspects of Computer Science (STACS)
TI - Efficient Computation of Optimal Energy and Fractional Weighted Flow Trade-off Schedules
ER -
TY - CONF
AB - In this survey article, we discuss two algorithmic research areas that emerge from problems that arise when resources are offered in the cloud. The first area, online leasing, captures problems arising from the fact that resources in the cloud are not bought, but leased by cloud vendors. The second area, Distributed Storage Systems, deals with problems arising from so-called cloud federations, i.e., when several cloud providers are needed to fulfill a given task.
AU - Kniesburges, Sebastian
AU - Markarian, Christine
AU - Meyer auf der Heide, Friedhelm
AU - Scheideler, Christian
ID - 459
T2 - Proceedings of the 21st International Colloquium on Structural Information and Communication Complexity (SIROCCO)
TI - Algorithmic Aspects of Resource Management in the Cloud
ER -
TY - CONF
AU - Hamann, Heiko
AU - Karsai, Istvan
AU - Schmickl, Thomas
AU - Hilbun, Allison
ID - 20007
T2 - Symposium on Biomathematics and Ecology: Education and Research
TI - The common stomach: Organizing task allocation in wasp societies
ER -
TY - CONF
AU - Birattari, Mauro
AU - Dorigo, Marco
AU - Hamann, Heiko
AU - Garnier, Simon
AU - Montes de Oca, Marco
AU - Solnon, Christine
AU - Stuetzle, Thomas
AU - Ding, Hongli
ID - 20127
T2 - Ninth Int. Conf. on Swarm Intelligence (ANTS 2014)
TI - Sorting in Swarm Robots Using Communication-Based Cluster Size Estimation
VL - 8667
ER -
TY - JOUR
AU - Polevoy, Gleb
AU - Smorodinsky, Rann
AU - Tennenholtz, Moshe
ID - 17662
IS - 1
JF - ACM Trans. Econ. Comput.
KW - Competition
KW - efficiency
KW - equilibrium
KW - market
KW - social welfare
SN - 2167-8375
TI - Signaling Competition and Social Welfare
VL - 2
ER -
TY - THES
AB - In meiner Dissertation besch{\"a}ftige ich mich mit dem Entwurf und der Analyse energieeffizienter Schedulingalgorithmen, insbesondere f{\"u}r sogenannte Speed-Scaling Modelle. Diese stellen das theoretische Pendant von Techniken wie AMDs PowerNOW! und Intels SpeedStep dar, welche es erlauben die Geschwindigkeit von Prozessoren zur Laufzeit an die derzeitigen Bedingungen anzupassen. Theoretische Untersuchungen solcher Modelle sind auf eine Arbeit von Yao, Demers und Shenker (FOCS'95) zur{\"u}ckzuf{\"u}hren. Hier kombinieren die Autoren klassisches Deadline-Scheduling mit einem Prozessor der Speed-Scaling beherrscht. Es gilt Jobs verschiedener Gr{\"o}ße fristgerecht abzuarbeiten und die dabei verwendete Energie zu minimieren. Der Energieverbrauch des Prozessors wird durch eine konvexe Funktion $\POW\colon\R_{\geq0}\to\R_{\geq0}$ modelliert, welche die Geschwindigkeit auf den Energieverbrauch abbildet.Meine Dissertation betrachtet verschiedene Varianten des urspr{\"u}nglichen Speed-Scaling Modells. Forschungsrelevante Ergebnisse sind in den Kapiteln 3 bis 6 zu finden und erstrecken sich {\"u}ber die im Folgenden beschriebenen Aspekte:- Kapitel 3 und 4 betrachten verschiedene \emph{Price-Collecting} Varianten des Originalproblems. Hier d{\"u}rfen einzelne Deadlines verfehlt werden, sofern eine jobabh{\"a}ngige Strafe gezahlt wird. Ich entwerfe insbesondere Online-Algorithmen mit einer beweisbar guten Competitiveness. Dabei liefern meine Ergebnisse substantielle Verbesserungen bestehender Arbeiten und erweitern diese unter Anderem auf Szenarien mit mehreren Prozessoren.- In Kapitel 5 wird statt des klassischen Deadline-Schedulings eine Linearkombination der durchschnittlichen Antwortzeit und des Energieverbrauchs betrachtet. Die Frage, ob dieses Problem NP-schwer ist, stellt eine der zentralen Forschungsfragen in diesem Gebiet dar. F{\"u}r eine relaxierte Form dieser Frage entwerfe ich einen effizienter Algorithmus und beweise seine Optimalit{\"a}t.- Das letzte Kapitel betrachtet ein Modell, welches – auf den ersten Blick – nicht direkt zur Speed-Scaling Literatur z{\"a}hlt. Hier geht es stattdessen um ein allgemeines Resource-Constrained Scheduling, in dem sich die Prozessoren zusammen eine gemeinsame, beliebig aufteilbare Ressource teilen. Ich untersuche die Komplexit{\"a}t des Problems und entwerfe verschiedene Approximationsalgorithmen.
AU - Kling, Peter
ID - 431
TI - Energy-efficient Scheduling Algorithms
ER -
TY - CONF
AB - In this paper we present and analyze HSkip+, a self-stabilizing overlay network for nodes with arbitrary heterogeneous bandwidths. HSkip+ has the same topology as the Skip+ graph proposed by Jacob et al. [PODC 2009] but its self-stabilization mechanism significantly outperforms the self-stabilization mechanism proposed for Skip+. Also, the nodes are now ordered according to their bandwidths and not according to their identifiers. Various other solutions have already been proposed for overlay networks with heterogeneous bandwidths, but they are not self-stabilizing. In addition to HSkip+ being self-stabilizing, its performance is on par with the best previous bounds on the time and work for joining or leaving a network of peers of logarithmic diameter and degree and arbitrary bandwidths. Also, the dilation and congestion for routing messages is on par with the best previous bounds for such networks, so that HSkip+ combines the advantages of both worlds. Our theoretical investigations are backed by simulations demonstrating that HSkip+ is indeed performing much better than Skip+ and working correctly under high churn rates.
AU - Feldotto, Matthias
AU - Scheideler, Christian
AU - Graffi, Kalman
ID - 412
T2 - Proceedings of the 14th IEEE International Conference on Peer-to-Peer Computing (P2P)
TI - HSkip+: A Self-Stabilizing Overlay Network for Nodes with Heterogeneous Bandwidths
ER -
TY - GEN
AU - Pahl, David
ID - 373
TI - Reputationssysteme für zusammengesetzte Dienstleistungen
ER -
TY - CONF
AB - Network creation games model the creation and usage costs of networks formed by n selfish nodes. Each node v can buy a set of edges, each for a fixed price α > 0. Its goal is to minimize its private costs, i.e., the sum (SUM-game, Fabrikant et al., PODC 2003) or maximum (MAX-game, Demaine et al., PODC 2007) of distances from v to all other nodes plus the prices of the bought edges. The above papers show the existence of Nash equilibria as well as upper and lower bounds for the prices of anarchy and stability. In several subsequent papers, these bounds were improved for a wide range of prices α. In this paper, we extend these models by incorporating quality-of-service aspects: Each edge cannot only be bought at a fixed quality (edge length one) for a fixed price α. Instead, we assume that quality levels (i.e., edge lengths) are varying in a fixed interval [βˇ,β^] , 0 series = {LNCS}
AU - Cord-Landwehr, Andreas
AU - Mäcker, Alexander
AU - Meyer auf der Heide, Friedhelm
ID - 380
T2 - Proceedings of the 10th International Conference on Web and Internet Economics (WINE)
TI - Quality of Service in Network Creation Games
ER -
TY - CONF
AB - We study the existence of approximate pure Nash equilibria in weighted congestion games and develop techniques to obtain approximate potential functions that prove the existence of alpha-approximate pure Nash equilibria and the convergence of alpha-improvement steps. Specifically, we show how to obtain upper bounds for approximation factor alpha for a given class of cost functions. For example for concave cost functions the factor is at most 3/2, for quadratic cost functions it is at most 4/3, and for polynomial cost functions of maximal degree d it is at at most d + 1. For games with two players we obtain tight bounds which are as small as for example 1.054 in the case of quadratic cost functions.
AU - Hansknecht, Christoph
AU - Klimm, Max
AU - Skopalik, Alexander
ID - 455
T2 - Proceedings of the 17th. International Workshop on Approximation Algorithms for Combinatorial Optimization Problems (APPROX)
TI - Approximate pure Nash equilibria in weighted congestion games
ER -
TY - CONF
AB - We discuss a technique to analyze complex infinitely repeated games using techniques from the fields of game theory and simulations. Our research is motivated by the analysis of electronic markets with thousands of participants and possibly complex strategic behavior. We consider an example of a global market of composed IT services to demonstrate the use of our simulation technique. We present our current work in this area and we want to discuss further approaches for the future.
AU - Feldotto, Matthias
AU - Skopalik, Alexander
ID - 462
T2 - Proceedings of the 4th International Conference on Simulation and Modeling Methodologies, Technologies and Applications (SIMULTECH 2014)
TI - A Simulation Framework for Analyzing Complex Infinitely Repeated Games
ER -
TY - CONF
AU - Hamann, Heiko
AU - Valentini, Gabriele
ID - 20008
SN - 0302-9743
T2 - Ninth Int. Conf. on Swarm Intelligence (ANTS 2014)
TI - Swarm in a Fly Bottle: Feedback-Based Analysis of Self-organizing Temporary Lock-ins
ER -
TY - CHAP
AU - Khaluf, Yara
AU - Dorigo, Marco
AU - Hamann, Heiko
AU - Valentini, Gabriele
AU - Bartz-Beielstein, T.
ID - 20128
T2 - 13th International Conference on Parallel Problem Solving from Nature (PPSN 2014)
TI - Derivation of a Micro-Macro Link for Collective Decision-Making Systems: Uncover Network Features Based on Drift Measurements
VL - 8672
ER -
TY - CONF
AU - Cervera, Enric
AU - Khaluf, Yara
AU - Birattari, Mauro
AU - Hamann, Heiko
AU - Pobil, Angel P. del
AU - Chinellato, Eris
AU - Martinez-Martin, Ester
AU - Hallam, John
AU - Morales, Antonio
ID - 20130
T2 - Simulation of Adaptive Behavior (SAB 2014)
TI - A Swarm Robotics Approach to Task Allocation Under Soft Deadlines and Negligible Switching Costs
VL - 8575
ER -
TY - CHAP
AU - Lukovszki, Tamás
AU - Meyer auf der Heide, Friedhelm
ID - 16394
SN - 0302-9743
T2 - Lecture Notes in Computer Science
TI - Fast Collisionless Pattern Formation by Anonymous, Position-Aware Robots
ER -
TY - BOOK
ED - Flocchini, Paola
ED - Gao, Jie
ED - Kranakis, Evangelos
ED - Meyer auf der Heide, Friedhelm
ID - 16870
SN - 0302-9743
TI - Algorithms for Sensor Systems - 9th International Symposium on Algorithms and Experiments for Sensor Systems, Wireless Networks and Distributed Robotics, {ALGOSENSORS} 2013
VL - 8243
ER -
TY - CONF
AB - In the leasing variant of Set Cover presented by Anthony et al.[1], elements U arrive over time and must be covered by sets from a familyF of subsets of U. Each set can be leased for K different periods of time.Let |U| = n and |F| = m. Leasing a set S for a period k incurs a cost ckS and allows S to cover its elements for the next lk time steps. The objectiveis to minimize the total cost of the sets leased, such that elements arrivingat any time t are covered by sets which contain them and are leased duringtime t. Anthony et al. [1] gave an optimal O(log n)-approximation forthe problem in the offline setting, unless P = NP [22]. In this paper, wegive randomized algorithms for variants of Set Cover Leasing in the onlinesetting, including a generalization of Online Set Cover with Repetitionspresented by Alon et al. [2], where elements appear multiple times andmust be covered by a different set at each arrival. Our results improve theO(log2(mn)) competitive factor of Online Set Cover with Repetitions [2]to O(log d log(dn)) = O(logmlog(mn)), where d is the maximum numberof sets an element belongs to.
AU - Abshoff, Sebastian
AU - Markarian, Christine
AU - Meyer auf der Heide, Friedhelm
ID - 379
T2 - Proceedings of the 8th Annual International Conference on Combinatorial Optimization and Applications (COCOA)
TI - Randomized Online Algorithms for Set Cover Leasing Problems
ER -
TY - CONF
AB - We introduce the concept of budget games. Players choose a set of tasks and each task has a certain demand on every resource in the game. Each resource has a budget. If the budget is not enough to satisfy the sum of all demands, it has to be shared between the tasks. We study strategic budget games, where the budget is shared proportionally. We also consider a variant in which the order of the strategic decisions influences the distribution of the budgets. The complexity of the optimal solution as well as existence, complexity and quality of equilibria are analysed. Finally, we show that the time an ordered budget game needs to convergence towards an equilibrium may be exponential.
AU - Drees, Maximilian
AU - Riechers, Sören
AU - Skopalik, Alexander
ED - Lavi, Ron
ID - 451
T2 - Proceedings of the 7th International Symposium on Algorithmic Game Theory (SAGT)
TI - Budget-restricted utility games with ordered strategic decisions
ER -
TY - CONF
AB - We study the existence of approximate pure Nash equilibriain social context congestion games. For any given set of allowed costfunctions F, we provide a threshold value μ(F), and show that for theclass of social context congestion games with cost functions from F, α-Nash dynamics are guaranteed to converge to α-approximate pure Nashequilibrium if and only if α > μ(F).Interestingly, μ(F) is related and always upper bounded by Roughgarden’sanarchy value [19].
AU - Gairing, Martin
AU - Kotsialou, Grammateia
AU - Skopalik, Alexander
ID - 456
T2 - Proceedings of the 10th International Conference on Web and Internet Economics (WINE)
TI - Approximate pure Nash equilibria in Social Context Congestion Games
ER -
TY - CONF
AU - Hamann, Heiko
AU - Sayama, Hiroki
AU - Rieffel, John
AU - Risi, Sebastian
AU - Doursat, Rene
AU - Lipson, Hod
ID - 20129
T2 - 14th Int. Conf. on the Synthesis and Simulation of Living Systems (ALIFE 2014)
TI - Evolution of Collective Behaviors by Minimizing Surprise
ER -
TY - CHAP
AU - Abshoff, Sebastian
AU - Meyer auf der Heide, Friedhelm
ID - 16395
SN - 0302-9743
T2 - Structural Information and Communication Complexity
TI - Continuous Aggregation in Dynamic Ad-Hoc Networks
ER -
TY - CONF
AB - We consider the problem of scheduling a number of jobs on $m$ identical processors sharing a continuously divisible resource. Each job j comes with a resource requirement r_j \in {0,1}. The job can be processed at full speed if granted its full resource requirement. If receiving only an x-portion of r_j, it is processed at an x-fraction of the full speed. Our goal is to find a resource assignment that minimizes the makespan (i.e., the latest completion time). Variants of such problems, relating the resource assignment of jobs to their \emph{processing speeds}, have been studied under the term discrete-continuous scheduling. Known results are either very pessimistic or heuristic in nature.In this paper, we suggest and analyze a slightly simplified model. It focuses on the assignment of shared continuous resources to the processors. The job assignment to processors and the ordering of the jobs have already been fixed. It is shown that, even for unit size jobs, finding an optimal solution is NP-hard if the number of processors is part of the input. Positive results for unit size jobs include an efficient optimal algorithm for 2 processors. Moreover, we prove that balanced schedules yield a 2-1/m-approximation for a fixed number of processors. Such schedules are computed by our GreedyBalance algorithm, for which the bound is tight.
AU - Brinkmann, Andre
AU - Kling, Peter
AU - Meyer auf der Heide, Friedhelm
AU - Nagel, Lars
AU - Riechers, Sören
AU - Süss, Tim
ID - 368
T2 - Proceedings of the 26th ACM Symposium on Parallelism in Algorithms and Architectures (SPAA)
TI - Scheduling Shared Continuous Resources on Many-Cores
ER -
TY - CONF
AB - Max-min fairness (MMF) is a widely known approach to a fair allocation of bandwidth to each of the users in a network. This allocation can be computed by uniformly raising the bandwidths of all users without violating capacity constraints. We consider an extension of these allocations by raising the bandwidth with arbitrary and not necessarily uniform time-depending velocities (allocation rates). These allocations are used in a game-theoretic context for routing choices, which we formalize in progressive filling games (PFGs).We present a variety of results for equilibria in PFGs. We show that these games possess pure Nash and strong equilibria. While computation in general is NP-hard, there are polynomial-time algorithms for prominent classes of Max-Min-Fair Games (MMFG), including the case when all users have the same source-destination pair. We characterize prices of anarchy and stability for pure Nash and strong equilibria in PFGs and MMFGs when players have different or the same source-destination pairs. In addition, we show that when a designer can adjust allocation rates, it is possible to design games with optimal strong equilibria. Some initial results on polynomial-time algorithms in this direction are also derived.
AU - Harks, Tobias
AU - Höfer, Martin
AU - Schewior, Kevin
AU - Skopalik, Alexander
ID - 370
T2 - Proceedings of the 33rd Annual IEEE International Conference on Computer Communications (INFOCOM'14)
TI - Routing Games with Progressive Filling
ER -
TY - THES
AU - Petring, Ralf
ID - 19039
TI - Multi-Algorithmen-Rendering: Darstellung heterogener 3-D-Szenen in Echtzeit
ER -
TY - JOUR
AB - A grand challenge in the field of artificial life is to find a general theory of emergent self-organizing systems. In swarm systems most of the observed complexity is based on motion of simple entities. Similarly, statistical mechanics focuses on collective properties induced by the motion of many interacting particles. In this article we apply methods from statistical mechanics to swarm systems. We try to explain the emergent behavior of a simulated swarm by applying methods based on the fluctuation theorem. Empirical results indicate that swarms are able to produce negative entropy within an isolated subsystem due to frozen accidents. Individuals of a swarm are able to locally detect fluctuations of the global entropy measure and store them, if they are negative entropy productions. By accumulating these stored fluctuations over time the swarm as a whole is producing negative entropy and the system ends up in an ordered state. We claim that this indicates the existence of an inverted fluctuation theorem for emergent self-organizing dissipative systems. This approach bears the potential of general applicability.
AU - Hamann, Heiko
AU - Schmickl, Thomas
AU - Crailsheim, Karl
ID - 20120
IS - 1
JF - Artificial Life
TI - Analysis of Swarm Behaviors Based on an Inversion of the Fluctuation Theorem
VL - 20
ER -
TY - CONF
AU - Polevoy, Gleb
AU - de Weerdt, Mathijs M.
ID - 17660
KW - dynamics
KW - emotion modeling
KW - negotiation
KW - network interaction
KW - shared effort game
SN - 978-1-4503-2738-1
T2 - Proceedings of the 2014 International Conference on Autonomous Agents and Multi-agent Systems
TI - Improving Human Interaction in Crowdsensing
ER -
TY - CONF
AB - Today's networks, like the Internet, do not consist of one but a mixture of several interconnected networks. Each has individual qualities and hence the performance of a network node results from the networks' interplay.We introduce a new game theoretic model capturing the interplay between a high-speed backbone network and a low-speed general purpose network. In our model, n nodes are connected by a static network and each node can decide individually to become a gateway node. A gateway node pays a fixed price for its connection to the high-speed network, but can utilize the high-speed network to gain communication distance 0 to all other gateways. Communication distances in the low-speed network are given by the hop distances. The effective communication distance between any two nodes then is given by the shortest path, which is possibly improved by using gateways as shortcuts.Every node v has the objective to minimize its communication costs, given by the sum (SUM-game) or maximum (MAX-game) of the effective communication distances from v to all other nodes plus a fixed price \alpha > 0, if it decides to be a gateway. For both games and different ranges of \alpha, we study the existence of equilibria, the price of anarchy, and convergence properties of best-response dynamics.
AU - Abshoff, Sebastian
AU - Cord-Landwehr, Andreas
AU - Jung, Daniel
AU - Skopalik, Alexander
ED - Lavi, Ron
ID - 452
T2 - Proceedings of the 7th International Symposium on Algorithmic Game Theory (SAGT)
TI - Brief Announcement: A Model for Multilevel Network Games
ER -
TY - CONF
AB - We consider the k-token dissemination problem, where k initially arbitrarily distributed tokens have to be disseminated to all nodes in a dynamic network (as introduced by Kuhn et al., STOC 2010). In contrast to general dynamic networks, our dynamic networks are unit disk graphs, i.e., nodes are embedded into the Euclidean plane and two nodes are connected if and only if their distance is at most R. Our worst-case adversary is allowed to move the nodes on the plane, but the maximum velocity v_max of each node is limited and the graph must be connected in each round. For this model, we provide almost tight lower and upper bounds for k-token dissemination if nodes are restricted to send only one token per round. It turns out that the maximum velocity v_max is a meaningful parameter to characterize dynamics in our model.
AU - Abshoff, Sebastian
AU - Benter, Markus
AU - Cord-Landwehr, Andreas
AU - Malatyali, Manuel
AU - Meyer auf der Heide, Friedhelm
ID - 477
T2 - Algorithms for Sensor Systems - 9th International Symposium on Algorithms and Experiments for Sensor Systems, Wireless Networks and Distributed Robotics, {ALGOSENSORS} 2013, Sophia Antipolis, France, September 5-6, 2013, Revised Selected Papers
TI - Token Dissemination in Geometric Dynamic Networks
ER -
TY - THES
AU - Eikel, Benjamin
ID - 17440
TI - Spherical visibility sampling : preprocessed visibility for occlusion culling in complex 3D scenes
ER -
TY - CONF
AB - 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.
AU - Happe, Markus
AU - Kling, Peter
AU - Plessl, Christian
AU - Platzner, Marco
AU - Meyer auf der Heide, Friedhelm
ID - 505
T2 - Proceedings of the 9th IEEE Workshop on Software Technology for Future embedded and Ubiquitous Systems (SEUS)
TI - On-The-Fly Computing: A Novel Paradigm for Individualized IT Services
ER -
TY - GEN
AB - 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.
AU - Meyer auf der Heide, Friedhelm
AU - Swirkot, Kamil
ID - 524
TI - Hierarchies in Local Distributed Decision
ER -
TY - CONF
AB - 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.
AU - Keller, Matthias
AU - Pawlik, Stefan
AU - Pietrzyk, Peter
AU - Karl, Holger
ID - 562
T2 - Proceedings of the 6th International Conference on Utility and Cloud Computing (UCC) workshop on Distributed cloud computing
TI - A Local Heuristic for Latency-Optimized Distributed Cloud Deployment
ER -
TY - CONF
AB - Viele virtuelle 3-D-Szenen im industriellen Bereich sind nicht gleichmäßig strukturiert, z.B. weil sie eine stark unterschiedliche Dichteverteilung der Polygone aufweisen. Für solch heterogene Daten existiert kein Algorithmus, der die Gesamtheit der Daten sowohl schnell als auch mit guter Qualität darstellen kann. Die Auswahl der richtigen Algorithmen für einzelne Szenenteile durch einen Experten ist zeitintensiv und in vielen Visualisierungssystemen nicht umzusetzen. Um dieses Problem zu lösen, setzt das hier vorgestellte Multi-Algorithmen-Rendering verschiedene Renderingalgorithmen gleichzeitig ein, um eine virtuelle 3-D-Szene darzustellen. Das Verfahren unterteilt die Szene dafür in einem Vorverarbeitungsschritt automatisch in geeignete Teilregionen und bestimmt deren Eigenschaften. Diese Daten werden zur Laufzeit dazu genutzt, um ständig für den aktuellen Standpunkt des Betrachters eine Abschätzung der Qualität und Laufzeit der zur Auswahl stehenden Renderingalgorithmen zu berechnen. Durch die Lösung eines Optimierungsproblems kann so bei vorgegebener Bildrate durch die passende Zuordnung der Algorithmen zu den Regionen die Bildqualität optimiert werden – bei automatischer Anpassung an die Leistungsfähigkeit der eingesetzten Hardware. In einer experimentellen Evaluierung vergleichen wir die Laufzeit und Bildqualität des Verfahrens mit denen verbreiteter Standardrenderingverfahren.
AU - Petring, Ralf
AU - Eikel, Benjamin
AU - Jähn, Claudius
AU - Fischer, Matthias
AU - Meyer auf der Heide, Friedhelm
ID - 17439
T2 - 11. Paderborner Workshop Augmented & Virtual Reality in der Produktentstehung
TI - Darstellung heterogener 3-D-Szenen in Echtzeit
VL - 311
ER -
TY - CONF
AU - Suess, Tim
AU - Schoenrock, Andrew
AU - Meisner, Sebastian
AU - Plessl, Christian
ID - 1787
SN - 978-0-7695-4979-8
T2 - Proc. Int. Symp. on Parallel and Distributed Processing Workshops (IPDPSW)
TI - Parallel Macro Pipelining on the Intel SCC Many-Core Computer
ER -
TY - CONF
AU - Hamann, Heiko
ID - 20160
T2 - 7th IEEE Int. Conf. on Self-Adaptive and Self-Organizing Systems (SASO 2013)
TI - A Reductionist Approach to Hypothesis-Catching for the Analysis of Self-Organizing Decision-Making Systems
ER -
TY - CONF
AB - 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.
AU - Markarian, Christine
AU - Meyer auf der Heide, Friedhelm
AU - Schubert, Michael
ID - 563
T2 - Proceedings of the 9th International Symposium on Algorithms and Experiments for Sensor Systems, Wireless Networks and Distributed Robotics (ALGOSENSORS)
TI - A Distributed Approximation Algorithm for Strongly Connected Dominating-Absorbent Sets in Asymmetric Wireless Ad-Hoc Networks
ER -
TY - CONF
AU - Meyer auf der Heide, Friedhelm
ID - 17442
T2 - 11. Paderborner Workshop Augmented & Virtual Reality in der Produktentstehung
TI - Algorithmische Grundlagen für die Selbstorganisation von Roboterschwärmen
VL - 311
ER -
TY - CONF
AB - 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.
AU - Eikel, Benjamin
AU - Jähn, Claudius
AU - Fischer, Matthias
AU - Meyer auf der Heide, Friedhelm
ID - 16393
IS - 4
SN - 0167-7055
T2 - Computer Graphics Forum
TI - Spherical Visibility Sampling
VL - 32
ER -
TY - CHAP
AB - 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.
AU - Jähn, Claudius
AU - Eikel, Benjamin
AU - Fischer, Matthias
AU - Petring, Ralf
AU - Meyer auf der Heide, Friedhelm
ID - 16406
SN - 0302-9743
T2 - Advances in Visual Computing
TI - Evaluation of Rendering Algorithms Using Position-Dependent Scene Properties
ER -
TY - JOUR
AU - Mertsching, Bärbel
AU - Divband Soorati, Mohammad
AU - Kotthauser, Tobias
ID - 19981
JF - IEEE International Conference on Robotics and Biomimetics (ROBIO)
TI - Automatic Reconstruction of Polygonal Room Models from 3D Point Clouds
ER -
TY - CONF
AU - Hamann, Heiko
AU - Lio, Pietro
AU - Miglino, Orazio
AU - Nicosia, Giuseppe
AU - Nolfi, Stefano
AU - Pavone, Mario
ID - 20161
T2 - 12th European Conference on Artificial Life (ECAL 2013)
TI - Speciation Dynamics: Generating Selective Pressure Towards Diversity
ER -
TY - JOUR
AB - In this paper, we define and study a new problem, referred to as the Dependent Unsplittable Flow Problem (D-UFP). We present and discuss this problem in the context of large-scale powerful (radar/camera) sensor networks, but we believe it has important applications on the admission of large flows in other networks as well. In order to optimize the selection of flows transmitted to the gateway, D-UFP takes into account possible dependencies between flows. We show that D-UFP is more difficult than NP-hard problems for which no good approximation is known. Then, we address two special cases of this problem: the case where all the sensors have a shared channel and the case where the sensors form a mesh and route to the gateway over a spanning tree.
AU - Cohen, R.
AU - Nudelman, I.
AU - Polevoy, Gleb
ID - 17663
IS - 5
JF - Networking, IEEE/ACM Transactions on
KW - Approximation algorithms
KW - Approximation methods
KW - Bandwidth
KW - Logic gates
KW - Radar
KW - Vectors
KW - Wireless sensor networks
KW - Dependent flow scheduling
KW - sensor networks
SN - 1063-6692
TI - On the Admission of Dependent Flows in Powerful Sensor Networks
VL - 21
ER -
TY - CONF
AB - 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.
AU - Abshoff, Sebastian
AU - Benter, Markus
AU - Malatyali, Manuel
AU - Meyer auf der Heide, Friedhelm
ID - 507
T2 - Proceedings of the 17th International Conference on Principles of Distributed Systems (OPODIS)
TI - On Two-Party Communication Through Dynamic Networks
ER -
TY - THES
AB - 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.
AU - Pietrzyk, Peter
ID - 514
TI - Local and Online Algorithms for Facility Location
ER -
TY - CONF
AB - We present a new online algorithm for profit-oriented scheduling on multiple speed-scalable processors.Moreover, we provide a tight analysis of the algorithm's competitiveness.Our results generalize and improve upon work by \citet{Chan:2010}, which considers a single speed-scalable processor.Using significantly different techniques, we can not only extend their model to multiprocessors but also prove an enhanced and tight competitive ratio for our algorithm.In our scheduling problem, jobs arrive over time and are preemptable.They have different workloads, values, and deadlines.The scheduler may decide not to finish a job but instead to suffer a loss equaling the job's value.However, to process a job's workload until its deadline the scheduler must invest a certain amount of energy.The cost of a schedule is the sum of lost values and invested energy.In order to finish a job the scheduler has to determine which processors to use and set their speeds accordingly.A processor's energy consumption is power $\Power{s}$ integrated over time, where $\Power{s}=s^{\alpha}$ is the power consumption when running at speed $s$.Since we consider the online variant of the problem, the scheduler has no knowledge about future jobs.This problem was introduced by~\citet{Chan:2010} for the case of a single processor.They presented an online algorithm which is $\alpha^{\alpha}+2e\alpha$-competitive.We provide an online algorithm for the case of multiple processors with an improved competitive ratio of $\alpha^{\alpha}$.
AU - Kling, Peter
AU - Pietrzyk, Peter
ID - 499
T2 - Proceedings of the 25th ACM Symposium on Parallelism in Algorithms and Architectures (SPAA)
TI - Profitable Scheduling on Multiple Speed-Scalable Processors
ER -
TY - GEN
ED - Gausemeier, Jürgen
ED - Grafe, Michael
ED - Meyer auf der Heide, Friedhelm
ID - 17443
TI - 11. Paderborner Workshop Augmented & Virtual Reality in der Produktentstehung
VL - 311
ER -
TY - CHAP
AB - 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.
AU - Petring, Ralf
AU - Eikel, Benjamin
AU - Jähn, Claudius
AU - Fischer, Matthias
AU - Meyer auf der Heide, Friedhelm
ID - 16407
SN - 0302-9743
T2 - Advances in Visual Computing
TI - Real-Time 3D Rendering of Heterogeneous Scenes
ER -
TY - JOUR
AU - Hamann, Heiko
AU - Schmickl, Thomas
AU - Stradner, Jürgen
AU - Crailsheim, Karl
AU - Thenius, Ronald
AU - Zahadat, Payam
ID - 20150
JF - Chaos, Solitons & Fractals
TI - Algorithmic Requirements for Swarm Intelligence in Differently Coupled Collective Systems
VL - 50
ER -
TY - JOUR
AU - Hamann, Heiko
AU - Karsai, Istvan
AU - Schmickl, Thomas
ID - 20148
IS - 7
JF - Bulletin of Mathematical Biology
TI - Time delay implies cost on task switching: A model to investigate the efficiency of task partitioning
VL - 75
ER -
TY - JOUR
AU - Hamann, Heiko
ID - 20162
IS - 3
JF - Swarm Intelligence
TI - Towards Swarm Calculus: Urn Models of Collective Decisions and Universal Properties of Swarm Performance
VL - 7
ER -
TY - GEN
ED - Flocchini, Paola
ED - Gao, Jie
ED - Kranakis, Evangelos
ED - Meyer auf der Heide, Friedhelm
ID - 558
TI - Algorithms for Sensor Systems - 9th International Symposium on Algorithms and Experiments for Sensor Systems, Wireless Networks and Distributed Robotics
VL - 8243
ER -
TY - CONF
AU - Hamann, Heiko
AU - Schmickl, Thomas
AU - Stradner, Jürgen
AU - Schwarzer, Christopher
AU - Michiels, Nico K.
AU - Esparcia-Alcazar, Anna Isabel
ID - 20151
T2 - Applications of Evolutionary Computation - 16th European Conference (EvoApplications 2013)
TI - Virtual Spatiality in Agent Controllers: Encoding Compartmentalization
VL - 7835
ER -
TY - CONF
AB - 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.
AU - Cord-Landwehr, Andreas
AU - Kling, Peter
AU - Mallmann Trenn, Fredrik
ED - Even, Guy
ED - Rawitz, Dror
ID - 580
T2 - Proceedings of the 1st Mediterranean Conference on Algorithms (MedAlg)
TI - Slow Down & Sleep for Profit in Online Deadline Scheduling
ER -
TY - CONF
AB - 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.
AU - Meyer auf der Heide, Friedhelm
AU - Pietrzyk, Peter
AU - Kling, Peter
ID - 636
T2 - Proceedings of the 19th International Colloquium on Structural Information & Communication Complexity (SIROCCO)
TI - An Algorithm for Facility Leasing
ER -
TY - JOUR
AU - Hamann, Heiko
AU - Schmickl, Thomas
AU - Crailsheim, Karl
ID - 20176
IS - 1
JF - Mathematical and Computer Modelling of Dynamical Systems
SN - 1387-3954
TI - Self-organized pattern formation in a swarm system as a transient phenomenon of non-linear dynamics
VL - 18
ER -
TY - JOUR
AB - 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.
AU - Damerow, Valentina
AU - Manthey, Bodo
AU - Meyer auf der Heide, Friedhelm
AU - Räcke, Harald
AU - Scheideler, Christian
AU - Sohler, Christian
AU - Tantau, Till
ID - 579
IS - 3
JF - Transactions on Algorithms
TI - Smoothed analysis of left-to-right maxima with applications
ER -
TY - CHAP
AU - Kempkes, Barbara
AU - Meyer auf der Heide, Friedhelm
ID - 16448
SN - 0302-9743
T2 - Algorithms for Sensor Systems
TI - Local, Self-organizing Strategies for Robotic Formation Problems
ER -
TY - THES
AB - 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.
AU - Kempkes, Barbara
ID - 601
TI - Local strategies for robot formation problems
ER -
TY - JOUR
AB - 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.
AU - Hamann, Heiko
AU - Schmickl, Thomas
AU - Crailsheim, Karl
ID - 20177
IS - 2
JF - Artificial Life
SN - 1064-5462
TI - A Hormone-Based Controller for Evaluation-Minimal Evolution in Decentrally Controlled Systems
VL - 18
ER -
TY - CONF
AB - 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.
AU - Drees, Maximilian
AU - Hüllmann (married name: Eikel), Martina
AU - Koutsopoulos, Andreas
AU - Scheideler, Christian
ID - 581
T2 - Proceedings of the 26th IEEE International Parallel and Distributed Processing Symposium (IPDPS)
TI - Self-Organizing Particle Systems
ER -
TY - CONF
AB - 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.
AU - Brandes, Philipp
AU - Meyer auf der Heide, Friedhelm
ID - 619
T2 - Proceedings of the 4th Workshop on Theoretical Aspects of Dynamic Distributed Systems (TADDS)
TI - Distributed Computing in Fault-Prone Dynamic Networks
ER -