TY - CHAP
AU - Feldkord, Björn
AU - Malatyali, Manuel
AU - Meyer auf der Heide, Friedhelm
ID - 16392
SN - 0302-9743
T2 - Progress in Pattern Recognition, Image Analysis, Computer Vision, and Applications
TI - A Dynamic Distributed Data Structure for Top-k and k-Select Queries
ER -
TY - CONF
AB - We consider a market where final products or services are compositions of a number of basic services. Users are asked to evaluate the quality of the composed product after purchase. The quality of the basic service influences the performance of the composed services but cannot be observed directly. The question we pose is whether it is possible to use user evaluations on composed services to assess the quality of basic services. We discuss how to combine aggregation of evaluations across users and disaggregation of information on composed services to derive valuations for the single components. As a solution we propose to use the (weighted) average as aggregation device in connection with the Shapley value as disaggregation method, since this combination fulfills natural requirements in our context. In addition, we address some occurring computational issues: We give an approximate solution concept using only a limited number of evaluations which guarantees nearly optimal results with reduced running time. Lastly, we show that a slightly modified Shapley value and the weighted average are still applicable if the evaluation profiles are incomplete.
AU - Feldotto, Matthias
AU - Haake, Claus-Jochen
AU - Skopalik, Alexander
AU - Stroh-Maraun, Nadja
ID - 2831
SN - 978-1-4503-5916-0
T2 - Proceedings of the 13th Workshop on Economics of Networks, Systems and Computation (NetEcon 2018)
TI - Disaggregating User Evaluations Using the Shapley Value
ER -
TY - JOUR
AU - Li, Shouwei
AU - Markarian, Christine
AU - Meyer auf der Heide, Friedhelm
ID - 2848
IS - 5
JF - Algorithmica
TI - Towards Flexible Demands in Online Leasing Problems.
VL - 80
ER -
TY - CONF
AB - We present a peer-to-peer network that supports the efficient processing of orthogonal range queries $R=\bigtimes_{i=1}^{d}[a_i,\,b_i]$ in a $d$-dimensional point space.\\
The network is the same for each dimension, namely a distance halving network like the one introduced by Naor and Wieder (ACM TALG'07).
We show how to execute such range queries using $\mathcal{O}\left(2^{d'}d\,\log m + d\,|R|\right)$ hops (and the same number of messages) in total. Here $[m]^d$ is the ground set, $|R|$ is the size and $d'$ the dimension of the queried range.
Furthermore, if the peers form a distributed network, the query can be answered in $\mathcal{O}\left(d\,\log m + d\,\sum_{i=1}^{d}(b_i-a_i+1)\right)$ communication rounds.
Our algorithms are based on a mapping of the Hilbert Curve through $[m]^d$ to the peers.
AU - Benter, Markus
AU - Knollmann, Till
AU - Meyer auf der Heide, Friedhelm
AU - Setzer, Alexander
AU - Sundermeier, Jannik
ID - 4375
KW - Distributed Storage
KW - Multi-Dimensional Range Queries
KW - Peer-to-Peer
KW - Hilbert Curve
T2 - Proceedings of the 4th International Symposium on Algorithmic Aspects of Cloud Computing (ALGOCLOUD)
TI - A Peer-to-Peer based Cloud Storage supporting orthogonal Range Queries of arbitrary Dimension
ER -
TY - CONF
AU - Jung, Daniel
AU - Kolb, Christina
AU - Scheideler, Christian
AU - Sundermeier, Jannik
ID - 4565
SN - 9781450357999
T2 - Proceedings of the 30th on Symposium on Parallelism in Algorithms and Architectures (SPAA)
TI - Brief Announcement: Competitive Routing in Hybrid Communication Networks
ER -
TY - CONF
AU - Hamann, Heiko
AU - Markarian, Christine
AU - Meyer auf der Heide, Friedhelm
AU - Wahby, Mostafa
ID - 2850
T2 - Ninth International Conference on Fun with Algorithms (FUN)
TI - Pick, Pack, & Survive: Charging Robots in a Modern Warehouse based on Online Connected Dominating Sets
ER -
TY - GEN
AB - We introduce the \emph{Online Connected Dominating Set Leasing} problem
(OCDSL) in which we are given an undirected connected graph $G = (V, E)$, a set
$\mathcal{L}$ of lease types each characterized by a duration and cost, and a
sequence of subsets of $V$ arriving over time. A node can be leased using lease
type $l$ for cost $c_l$ and remains active for time $d_l$. The adversary gives
in each step $t$ a subset of nodes that need to be dominated by a connected
subgraph consisting of nodes active at time $t$. The goal is to minimize the
total leasing costs. OCDSL contains the \emph{Parking Permit
Problem}~\cite{PPP} as a special subcase and generalizes the classical offline
\emph{Connected Dominating Set} problem~\cite{Guha1998}. It has an $\Omega(\log
^2 n + \log |\mathcal{L}|)$ randomized lower bound resulting from lower bounds
for the \emph{Parking Permit Problem} and the \emph{Online Set Cover}
problem~\cite{Alon:2003:OSC:780542.780558,Korman}, where $|\mathcal{L}|$ is the
number of available lease types and $n$ is the number of nodes in the input
graph. We give a randomized $\mathcal{O}(\log ^2 n + \log |\mathcal{L}| \log
n)$-competitive algorithm for OCDSL. We also give a deterministic algorithm for
a variant of OCDSL in which the dominating subgraph need not be connected, the
\emph{Online Dominating Set Leasing} problem. The latter is based on a simple
primal-dual approach and has an $\mathcal{O}(|\mathcal{L}| \cdot
\Delta)$-competitive ratio, where $\Delta$ is the maximum degree of the input
graph.
AU - Markarian, Christine
ID - 19978
T2 - arXiv:1805.02994
TI - Online Connected Dominating Set Leasing
ER -
TY - GEN
AU - Nachtigall, Marcel
ID - 1187
TI - Scenario-driven Strategy Analysis in a n-player Composition Game Model
ER -
TY - JOUR
AU - Abu-Khzam, Faisal N.
AU - Markarian, Christine
AU - Meyer auf der Heide, Friedhelm
AU - Schubert, Michael
ID - 2849
JF - Theory of Computing Systems
TI - Approximation and Heuristic Algorithms for Computing Backbones in Asymmetric Ad-hoc Networks
ER -
TY - JOUR
AU - König, Jürgen
AU - Mäcker, Alexander
AU - Meyer auf der Heide, Friedhelm
AU - Riechers, Sören
ID - 3551
IS - 4
JF - Journal of Combinatorial Optimization
TI - Scheduling with interjob communication on parallel processors
VL - 36
ER -
TY - JOUR
AB - We study a new class of games which generalizes congestion games andits bottleneck variant. We introduce congestion games with mixed objectives to modelnetwork scenarios in which players seek to optimize for latency and bandwidths alike.We characterize the (non-)existence of pure Nash equilibria (PNE), the convergenceof improvement dynamics, the quality of equilibria and show the complexity of thedecision problem. For games that do not possess PNE we give bounds on the approx-imation ratio of approximate pure Nash equilibria.
AU - Feldotto, Matthias
AU - Leder, Lennart
AU - Skopalik, Alexander
ID - 669
IS - 4
JF - Journal of Combinatorial Optimization
SN - 1382-6905
TI - Congestion games with mixed objectives
VL - 36
ER -
TY - JOUR
AU - Althaus, Ernst
AU - Brinkmann, Andre
AU - Kling, Peter
AU - Meyer auf der Heide, Friedhelm
AU - Nagel, Lars
AU - Riechers, Sören
AU - Sgall, Jiri
AU - Süß, Tim
ID - 63
IS - 1
JF - Journal of Scheduling
TI - Scheduling Shared Continuous Resources on Many-Cores
VL - 21
ER -
TY - GEN
AU - Kempf, Jérôme
ID - 1188
TI - Learning deterministic bandit behaviour form compositions
ER -
TY - CONF
AB - We study the classic bin packing problem in a fully-dynamic setting, where new items can arrive and old items may depart. We want algorithms with low asymptotic competitive ratio while repacking items sparingly between updates. Formally, each item i has a movement cost c_i >= 0, and we want to use alpha * OPT bins and incur a movement cost gamma * c_i, either in the worst case, or in an amortized sense, for alpha, gamma as small as possible. We call gamma the recourse of the algorithm. This is motivated by cloud storage applications, where fully-dynamic bin packing models the problem of data backup to minimize the number of disks used, as well as communication incurred in moving file backups between disks. Since the set of files changes over time, we could recompute a solution periodically from scratch, but this would give a high number of disk rewrites, incurring a high energy cost and possible wear and tear of the disks. In this work, we present optimal tradeoffs between number of bins used and number of items repacked, as well as natural extensions of the latter measure.
AU - Feldkord, Björn
AU - Feldotto, Matthias
AU - Gupta, Anupam
AU - Guruganesh, Guru
AU - Kumar, Amit
AU - Riechers, Sören
AU - Wajc, David
ED - Chatzigiannakis, Ioannis
ED - Kaklamanis, Christos
ED - Marx, Dániel
ED - Sannella, Donald
ID - 2484
SN - 1868-8969
T2 - 45th International Colloquium on Automata, Languages, and Programming (ICALP 2018)
TI - Fully-Dynamic Bin Packing with Little Repacking
VL - 107
ER -
TY - CONF
AB - While a lot of research in distributed computing has covered solutions for self-stabilizing computing and topologies, there is far less work on self-stabilization for distributed data structures.
Considering crashing peers in peer-to-peer networks, it should not be taken for granted that a distributed data structure remains intact.
In this work, we present a self-stabilizing protocol for a distributed data structure called the hashed Patricia Trie (Kniesburges and Scheideler WALCOM'11) that enables efficient prefix search on a set of keys.
The data structure has a wide area of applications including string matching problems while offering low overhead and efficient operations when embedded on top of a distributed hash table.
Especially, longest prefix matching for $x$ can be done in $\mathcal{O}(\log |x|)$ hash table read accesses.
We show how to maintain the structure in a self-stabilizing way.
Our protocol assures low overhead in a legal state and a total (asymptotically optimal) memory demand of $\Theta(d)$ bits, where $d$ is the number of bits needed for storing all keys.
AU - Knollmann, Till
AU - Scheideler, Christian
ED - Izumi, Taisuke
ED - Kuznetsov, Petr
ID - 4411
KW - Self-Stabilizing
KW - Prefix Search
KW - Distributed Data Structure
T2 - Proceedings of the 20th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS)
TI - A Self-Stabilizing Hashed Patricia Trie
VL - 11201
ER -
TY - CONF
AU - Feldkord, Björn
AU - Meyer auf der Heide, Friedhelm
ID - 2485
T2 - Proceedings of the 30th ACM Symposium on Parallelism in Algorithms and Architectures (SPAA)
TI - Online Facility Location with Mobile Facilities
ER -
TY - GEN
AU - Koop, Samuel
ID - 3851
TI - Congestion Games mit gewichteten Strategien
ER -
TY - CONF
AB - Routing is a challenging problem for wireless ad hoc networks, especially when the nodes are mobile and spread so widely that in most cases multiple hops are needed to route a message from one node to another. In fact, it is known that any online routing protocol has a poor performance in the worst case, in a sense that there is a distribution of nodes resulting in bad routing paths for that protocol, even if the nodes know their geographic positions and the geographic position of the destination of a message is known. The reason for that is that radio holes in the ad hoc network may require messages to take long detours in order to get to a destination, which are hard to find in an online fashion.
In this paper, we assume that the wireless ad hoc network can make limited use of long-range links provided by a global communication infrastructure like a cellular infrastructure or a satellite in order to compute an abstraction of the wireless ad hoc network that allows the messages to be sent along near-shortest paths in the ad hoc network. We present distributed algorithms that compute an abstraction of the ad hoc network in $\mathcal{O}\left(\log ^2 n\right)$ time using long-range links, which results in $c$-competitive routing paths between any two nodes of the ad hoc network for some constant $c$ if the convex hulls of the radio holes do not intersect. We also show that the storage needed for the abstraction just depends on the number and size of the radio holes in the wireless ad hoc network and is independent on the total number of nodes, and this information just has to be known to a few nodes for the routing to work.
AU - Jung, Daniel
AU - Kolb, Christina
AU - Scheideler, Christian
AU - Sundermeier, Jannik
ID - 4563
KW - greedy routing
KW - ad hoc networks
KW - convex hulls
KW - c-competitiveness
T2 - Proceedings of the 14th International Symposium on Algorithms and Experiments for Wireless Networks (ALGOSENSORS)
TI - Competitive Routing in Hybrid Communication Networks
ER -
TY - THES
AB - My dissertation deals with the Gathering problem for swarms of n point-shaped robots on a grid, in which all robots of the swarm are supposed to gather at a previously undefined point. Special attention is paid to the strong limitation of robot capabilities. These include in particular the lack of global control, a global compass, global visibility and (global) communication skills. Furthermore, all robots are identical. The robots are given only local abilities. This includes a constant range of vision. The robots all work completely synchronously. In this work we present and analyze three different Gathering strategies in different robot models. We formally prove correctness and total running time: Chapter 4 focuses on minimizing the available robot capabilities. The underlying strategy completes the gathering in O(n^2) time. For the following Chapters 5 and 6, the aim is to optimize the total running time under using only local robot capabilities: We additionally allow a constant-sized memory and a constant number of locally visible statuses (lights, flags). For the strategies of both chapters we show an asymptotically optimal running time of O(n). Unlike in Chapters 4 and 5, we additionally restrict connectivity and vision to an initially given chain connectivity in Chapter 6, where two chain neighbors must have a distance of 1 from each other. A robot can only see and interact with a constant number of its direct chain neighbors.
AU - Jung, Daniel
ID - 1209
SN - 978-3-942647-99-1
TI - Local Strategies for Swarm Formations on a Grid
ER -
TY - GEN
AU - Geromel, Marcel
ID - 5403
TI - Mobile Facility Leasing
ER -
TY - CONF
AB - We study a model of selfish resource allocation that seeks to incorporate dependencies among resources as they exist in in modern networked environments. Our model is inspired by utility functions with constant elasticity of substitution (CES) which is a well-studied model in economics. We consider congestion games with different aggregation functions. In particular, we study $L_p$ norms and analyze the existence and complexity of (approximate) pure Nash equilibria. Additionally, we give an almost tight characterization based on monotonicity properties to describe the set of aggregation functions that guarantee the existence of pure Nash equilibria.
AU - Feldotto, Matthias
AU - Leder, Lennart
AU - Skopalik, Alexander
ID - 112
T2 - Proceedings of the 10th International Conference on Algorithms and Complexity (CIAC)
TI - Congestion Games with Complementarities
ER -
TY - CONF
AB - In der CAD-unterstützten Entwicklung von technischen Systemen (Maschinen, Anlagen etc.) werden virtuelle Prototypen im Rahmen eines virtuellen Design-Reviews mit Hilfe eines VR-Systems gesamtheitlich betrachtet, um frühzeitig Fehler und Verbesserungsbedarf zu erkennen. Ein wichtiger Untersuchungsgegenstand ist dabei die Analyse von Transportwegen für den Materialtransport mittels Fließbändern, Förderketten oder schienenbasierten Transportsystemen. Diese Transportwege werden im VR-System animiert. Problematisch dabei ist, dass derartige Transportsysteme im zugrundeliegenden CAD-Modell in der Praxis oft nicht modelliert und nur exemplarisch angedeutet werden, da diese für die Konstruktion nicht relevant sind (z.B. der Fördergurt eines Förderbandes, oder die Kette einer Förderkette), oder die Informationen über den Verlauf bei der Konvertierung der Daten in das VR-System verloren gehen. Bei der Animation dieser Transportsysteme in einem VR-System muss der Transportweg also aufwändig, manuell nachgearbeitet werden. Das Ziel dieser Arbeit ist die Reduzierung des notwendigen manuellen Nachbearbeitungsaufwandes für das Design-Review durch eine automatische Berechnung der Animationspfade entlang eines Transportsystems. Es wird ein Algorithmus vorgestellt, der es ermöglicht mit nur geringem zeitlichem Benutzeraufwand den Animationspfad aus den reinen polygonalen dreidimensionalen Daten eines Transportsystems automatisch zu rekonstruieren.
AU - Brandt, Sascha
AU - Fischer, Matthias
ID - 16339
T2 - Wissenschaftsforum Intelligente Technische Systeme (WInTeSys) 2017
TI - Automatische Ableitung der Transportwege von Transportsystemen aus dem 3D-Polygonmodell
VL - 369
ER -
TY - CONF
AB - We consider a scheduling problem on $m$ identical processors sharing an arbitrarily divisible resource. In addition to assigning jobs to processors, the scheduler must distribute the resource among the processors (e.g., for three processors in shares of 20\%, 15\%, and 65\%) and adjust this distribution over time. Each job $j$ comes with a size $p_j \in \mathbb{R}$ and a resource requirement $r_j > 0$. Jobs do not benefit when receiving a share larger than $r_j$ of the resource. But providing them with a fraction of the resource requirement causes a linear decrease in the processing efficiency. We seek a (non-preemptive) job and resource assignment minimizing the makespan.Our main result is an efficient approximation algorithm which achieves an approximation ratio of $2 + 1/(m-2)$. It can be improved to an (asymptotic) ratio of $1 + 1/(m-1)$ if all jobs have unit size. Our algorithms also imply new results for a well-known bin packing problem with splittable items and a restricted number of allowed item parts per bin.Based upon the above solution, we also derive an approximation algorithm with similar guarantees for a setting in which we introduce so-called tasks each containing several jobs and where we are interested in the average completion time of tasks (a task is completed when all its jobs are completed).
AU - Kling, Peter
AU - Mäcker, Alexander
AU - Riechers, Sören
AU - Skopalik, Alexander
ID - 59
T2 - Proceedings of the 29th ACM Symposium on Parallelism in Algorithms and Architectures (SPAA)
TI - Sharing is Caring: Multiprocessor Scheduling with a Sharable Resource
ER -
TY - CONF
AB - In budget games, players compete over resources with finite budgets. For every resource, a player has a specific demand and as a strategy, he chooses a subset of resources. If the total demand on a resource does not exceed its budget, the utility of each player who chose that resource equals his demand. Otherwise, the budget is shared proportionally. In the general case, pure Nash equilibria (NE) do not exist for such games. In this paper, we consider the natural classes of singleton and matroid budget games with additional constraints and show that for each, pure NE can be guaranteed. In addition, we introduce a lexicographical potential function to prove that every matroid budget game has an approximate pure NE which depends on the largest ratio between the different demands of each individual player.
AU - Drees, Maximilian
AU - Feldotto, Matthias
AU - Riechers, Sören
AU - Skopalik, Alexander
ID - 66
T2 - Proceedings of the 23rd International Computing and Combinatorics Conference (COCOON)
TI - Pure Nash Equilibria in Restricted Budget Games
ER -
TY - CHAP
AU - Bemmann, Pascal
AU - Biermeier, Felix
AU - Bürmann, Jan
AU - Kemper, Arne
AU - Knollmann, Till
AU - Knorr, Steffen
AU - Kothe, Nils
AU - Mäcker, Alexander
AU - Malatyali, Manuel
AU - Meyer auf der Heide, Friedhelm
AU - Riechers, Sören
AU - Schaefer, Johannes
AU - Sundermeier, Jannik
ID - 16461
SN - 0302-9743
T2 - Structural Information and Communication Complexity
TI - Monitoring of Domain-Related Problems in Distributed Data Streams
ER -
TY - JOUR
AU - Mäcker, Alexander
AU - Malatyali, Manuel
AU - Meyer auf der Heide, Friedhelm
AU - Riechers, Sören
ID - 706
IS - 4
JF - Journal of Combinatorial Optimization
TI - Cost-efficient Scheduling on Machines from the Cloud
VL - 36
ER -
TY - CONF
AB - Bridging the gap between informal, imprecise, and vague user requirements descriptions and precise formalized specifications is the main task of requirements engineering. Techniques such as interviews or story telling are used when requirements engineers try to identify a user's needs. The requirements specification process is typically done in a dialogue between users, domain experts, and requirements engineers. In our research, we aim at automating the specification of requirements. The idea is to distinguish between untrained users and trained users, and to exploit domain knowledge learned from previous runs of our system. We let untrained users provide unstructured natural language descriptions, while we allow trained users to provide examples of behavioral descriptions. In both cases, our goal is to synthesize formal requirements models similar to statecharts. From requirements specification processes with trained users, behavioral ontologies are learned which are later used to support the requirements specification process for untrained users. Our research method is original in combining natural language processing and search-based techniques for the synthesis of requirements specifications. Our work is embedded in a larger project that aims at automating the whole software development and deployment process in envisioned future software service markets.
AU - van Rooijen, Lorijn
AU - Bäumer, Frederik Simon
AU - Platenius, Marie Christin
AU - Geierhos, Michaela
AU - Hamann, Heiko
AU - Engels, Gregor
ID - 97
KW - Software
KW - Unified modeling language
KW - Requirements engineering
KW - Ontologies
KW - Search problems
KW - Natural languages
SN - 978-1-5386-3489-9
T2 - 2017 IEEE 25th International Requirements Engineering Conference Workshops (REW)
TI - From User Demand to Software Service: Using Machine Learning to Automate the Requirements Specification Process
ER -
TY - GEN
AU - Bürmann, Jan
ID - 1080
TI - Complexity of Signalling in Routing Games under Uncertainty
ER -
TY - GEN
AU - Nachtigall, Simon
ID - 1073
TI - Sortieren dynamischer Daten
ER -
TY - CONF
AB - We study the computation of approximate pure Nash equilibria in Shapley value (SV) weighted congestion games, introduced in [19]. This class of games considers weighted congestion games in which Shapley values are used as an alternative (to proportional shares) for distributing the total cost of each resource among its users. We focus on the interesting subclass of such games with polynomial resource cost functions and present an algorithm that computes approximate pure Nash equilibria with a polynomial number of strategy updates. Since computing a single strategy update is hard, we apply sampling techniques which allow us to achieve polynomial running time. The algorithm builds on the algorithmic ideas of [7], however, to the best of our knowledge, this is the first algorithmic result on computation of approximate equilibria using other than proportional shares as player costs in this setting. We present a novel relation that approximates the Shapley value of a player by her proportional share and vice versa. As side results, we upper bound the approximate price of anarchy of such games and significantly improve the best known factor for computing approximate pure Nash equilibria in weighted congestion games of [7].
AU - Feldotto, Matthias
AU - Gairing, Martin
AU - Kotsialou, Grammateia
AU - Skopalik, Alexander
ID - 113
T2 - Proceedings of the 13th International Conference on Web and Internet Economics (WINE)
TI - Computing Approximate Pure Nash Equilibria in Shapley Value Weighted Congestion Games
ER -
TY - CONF
AU - Fischer, Matthias
AU - Jung, Daniel
AU - Meyer auf der Heide, Friedhelm
ED - Fernández Anta, Antonio
ED - Jurdzinski, Tomasz
ED - Mosteiro, Miguel A.
ED - Zhang, Yanyong
ID - 16347
T2 - Algorithms for Sensor Systems - 13th International Symposium on Algorithms and Experiments for Wireless Sensor Networks, {ALGOSENSORS}
TI - Gathering Anonymous, Oblivious Robots on a Grid
VL - 10718
ER -
TY - CONF
AB - We introduce the mobile server problem, inspired by current trends to move computational tasks from cloud structures to multiple devices close to the end user. An example for this are embedded systems in autonomous cars that communicate in order to coordinate their actions. Our model is a variant of the classical Page Migration Problem. Moreformally, we consider a mobile server holding a data page.The server can move in the Euclidean space (of arbitrary dimension). In every round, requests for data items from the page pop up at arbitrary points in the space. The requests are served, each at a cost of the distance from the requesting point and the server, and the mobile server may move, at a cost D times the distance traveled for some constant D . We assume a maximum distance m the server is allowed to move per round. We show that no online algorithm can achieve a competitive ratio independent of the length of the input sequence in this setting. Hence we augment the maximum movement distance of the online algorithms to ( 1 + δ) times the maximum distance of the offline solution. We provide a deterministic algorithm which is simple to describe and works for multiple variants of our problem. The algorithm achieves almost tight competitive ratios independent of the length of the input sequence.
AU - Feldkord, Björn
AU - Meyer auf der Heide, Friedhelm
ID - 55
T2 - Proceedings of the 29th ACM Symposium on Parallelism in Algorithms and Architectures (SPAA)
TI - The Mobile Server Problem
ER -
TY - CONF
AB - Consider a problem in which $n$ jobs that are classified into $k$ types arrive over time at their release times and are to be scheduled on a single machine so as to minimize the maximum flow time.The machine requires a setup taking $s$ time units whenever it switches from processing jobs of one type to jobs of a different type.We consider the problem as an online problem where each job is only known to the scheduler as soon as it arrives and where the processing time of a job only becomes known upon its completion (non-clairvoyance).We are interested in the potential of simple ``greedy-like'' algorithms.We analyze a modification of the FIFO strategy and show its competitiveness to be $\Theta(\sqrt{n})$, which is optimal for the considered class of algorithms.For $k=2$ types it achieves a constant competitiveness.Our main insight is obtained by an analysis of the smoothed competitiveness.If processing times $p_j$ are independently perturbed to $\hat p_j = (1+X_j)p_j$, we obtain a competitiveness of $O(\sigma^{-2} \log^2 n)$ when $X_j$ is drawn from a uniform or a (truncated) normal distribution with standard deviation $\sigma$.The result proves that bad instances are fragile and ``practically'' one might expect a much better performance than given by the $\Omega(\sqrt{n})$-bound.
AU - Mäcker, Alexander
AU - Malatyali, Manuel
AU - Meyer auf der Heide, Friedhelm
AU - Riechers, Sören
ID - 79
T2 - Proceedings of the 15th Workshop on Approximation and Online Algorithms (WAOA)
TI - Non-Clairvoyant Scheduling to Minimize Max Flow Time on a Machine with Setup Times
VL - 10787
ER -
TY - GEN
AU - Vijayalakshmi, Vipin Ravindran
ID - 1081
TI - Bounding the Inefficiency of Equilibria in Congestion Games under Taxation
ER -
TY - GEN
AU - Pukrop, Simon
ID - 1074
TI - Robuste Optimierung in Congestion Games
ER -
TY - CONF
AU - Biermeier, Felix
AU - Feldkord, Björn
AU - Malatyali, Manuel
AU - Meyer auf der Heide, Friedhelm
ID - 16348
T2 - Proceedings of the 15th Workshop on Approximation and Online Algorithms (WAOA)
TI - A Communication-Efficient Distributed Data Structure for Top-k and k-Select Queries
ER -
TY - CONF
AU - Markarian, Christine
ID - 2851
T2 - International Conference on Operations Research (OR)
TI - Leasing with Uncertainty
ER -
TY - GEN
AU - Nowack, Joshua
ID - 695
TI - On-The-Fly Konstruktion zusammenhängender Straßennetze aus gegebenen Einzelteilen
ER -
TY - CONF
AU - Feldkord, Björn
AU - Markarian, Christine
AU - Meyer auf der Heide, Friedhelm
ID - 70
T2 - Proceedings of the 11th Annual International Conference on Combinatorial Optimization and Applications (COCOA)
TI - Price Fluctuations in Online Leasing
ER -
TY - CONF
AB - Many graph problems such as maximum cut, chromatic number, hamiltonian cycle, and edge dominating set are known to be fixed-parameter tractable (FPT) when parameterized by the treewidth of the input graphs, but become W-hard with respect to the clique-width parameter. Recently, Gajarský et al. proposed a new parameter called modular-width using the notion of modular decomposition of graphs. They showed that the chromatic number problem and the partitioning into paths problem, and hence hamiltonian path and hamiltonian cycle, are FPT when parameterized by this parameter. In this paper, we study modular-width in parameterized parallel complexity and show that the weighted maximum clique problem and the maximum matching problem are fixed-parameter parallel-tractable (FPPT) when parameterized by this parameter.
AU - Abu-Khzam, Faisal N.
AU - Li, Shouwei
AU - Markarian, Christine
AU - Meyer auf der Heide, Friedhelm
AU - Podlipyan, Pavel
ID - 82
T2 - Proceedings of the 11th International Workshop on Frontiers in Algorithmics (FAW)
TI - Modular-Width: An Auxiliary Parameter for Parameterized Parallel Complexity
ER -
TY - BOOK
AU - Gausemeier, Jürgen
AU - Bodden, Eric
AU - Dressler, Falko
AU - Dumitrescu, Roman
AU - Meyer auf der Heide, Friedhelm
AU - Scheytt, Christoph
AU - Trächtler, Ansgar
ID - 16444
TI - Wissenschaftsforum Intelligente Technische Systeme (WInTeSys)
ER -
TY - THES
AU - Podlipyan, Pavel
ID - 703
TI - Local Algorithms for the Continuous Gathering Problem
ER -
TY - JOUR
AB - We consider an extension of the dynamic speed scaling scheduling model introduced by Yao et al.: A set of jobs, each with a release time, deadline, and workload, has to be scheduled on a single, speed-scalable processor. Both the maximum allowed speed of the processor and the energy costs may vary continuously over time. The objective is to find a feasible schedule that minimizes the total energy costs. Theoretical algorithm design for speed scaling problems often tends to discretize problems, as our tools in the discrete realm are often better developed or understood. Using the above speed scaling variant with variable, continuous maximal processor speeds and energy prices as an example, we demonstrate that a more direct approach via tools from variational calculus can not only lead to a very concise and elegant formulation and analysis, but also avoids the “explosion of variables/constraints” that often comes with discretizing. Using well-known tools from calculus of variations, we derive combinatorial optimality characteristics for our continuous problem and provide a quite concise and simple correctness proof.
AU - Antoniadis, Antonios
AU - Kling, Peter
AU - Ott, Sebastian
AU - Riechers, Sören
ID - 110
JF - Theoretical Computer Science
TI - Continuous Speed Scaling with Variability: A Simple and Direct Approach
ER -
TY - CONF
AB - Many university students struggle with motivational problems, and gamification has the potential to address these problems. However, gamification is hardly used in education, because current approaches to gamification require instructors to engage in the time-consuming preparation of their course contents for use in quizzes, mini-games and the like. Drawing on research on limited attention and present bias, we propose a "lean" approach to gamification, which relies on gamifying learning activities (rather than learning contents) and increasing their salience. In this paper, we present the app StudyNow that implements such a lean gamification approach. With this app, we aim to enable more students and instructors to benefit from the advantages of gamification.
AU - Feldotto, Matthias
AU - John, Thomas
AU - Kundisch, Dennis
AU - Hemsen, Paul
AU - Klingsieck, Katrin
AU - Skopalik, Alexander
ID - 1094
T2 - Proceedings of the 12th International Conference on Design Science Research in Information Systems and Technology (DESRIST)
TI - Making Gamification Easy for the Professor: Decoupling Game and Content with the StudyNow Mobile App
ER -
TY - CONF
AU - Podlipyan, Pavel
AU - Li, Shouwei
AU - Markarian, Christine
AU - Meyer auf der Heide, Friedhelm
ID - 16349
T2 - Proceedings of the 13th International Symposium on Algorithms and Experiments for Wireless Networks (ALGOSENSORS)
TI - A Continuous Strategy for Collisionless Gathering
ER -
TY - THES
AU - Riechers, Sören
ID - 704
TI - Scheduling with Scarce Resources
ER -
TY - GEN
AB - We consider a swarm of $n$ autonomous mobile robots, distributed on a
2-dimensional grid. A basic task for such a swarm is the gathering process: All
robots have to gather at one (not predefined) place. A common local model for
extremely simple robots is the following: The robots do not have a common
compass, only have a constant viewing radius, are autonomous and
indistinguishable, can move at most a constant distance in each step, cannot
communicate, are oblivious and do not have flags or states. The only gathering
algorithm under this robot model, with known runtime bounds, needs
$\mathcal{O}(n^2)$ rounds and works in the Euclidean plane. The underlying time
model for the algorithm is the fully synchronous $\mathcal{FSYNC}$ model. On
the other side, in the case of the 2-dimensional grid, the only known gathering
algorithms for the same time and a similar local model additionally require a
constant memory, states and "flags" to communicate these states to neighbors in
viewing range. They gather in time $\mathcal{O}(n)$.
In this paper we contribute the (to the best of our knowledge) first
gathering algorithm on the grid that works under the same simple local model as
the above mentioned Euclidean plane strategy, i.e., without memory (oblivious),
"flags" and states. We prove its correctness and an $\mathcal{O}(n^2)$ time
bound in the fully synchronous $\mathcal{FSYNC}$ time model. This time bound
matches the time bound of the best known algorithm for the Euclidean plane
mentioned above. We say gathering is done if all robots are located within a
$2\times 2$ square, because in $\mathcal{FSYNC}$ such configurations cannot be
solved.
AU - Fischer, Matthias
AU - Jung, Daniel
AU - Meyer auf der Heide, Friedhelm
ID - 17811
T2 - arXiv:1702.03400
TI - Gathering Anonymous, Oblivious Robots on a Grid
ER -
TY - CONF
AB - Many university students struggle with motivational problems, and gamification has the potential to address these problems. However, using gamification currently is rather tedious and time-consuming for instructors because current approaches to gamification require instructors to engage in the time-consuming preparation of course contents (e.g., for quizzes or mini-games). In reply to this issue, we propose a “lean” approach to gamification, which relies on gamifying learning activities rather than learning contents. The learning activities that are gamified in the lean approach can typically be drawn from existing course syllabi (e.g., attend certain lectures, hand in assignments, read book chapters and articles). Hence, compared to existing approaches, lean gamification substantially lowers the time requirements posed on instructors for gamifying a given course. Drawing on research on limited attention and the present bias, we provide the theoretical foundation for the lean gamification approach. In addition, we present a mobile application that implements lean gamification and outline a mixed-methods study that is currently under way for evaluating whether lean gamification does indeed have the potential to increase students’ motivation. We thereby hope to allow more students and instructors to benefit from the advantages of gamification.
AU - John, Thomas
AU - Feldotto, Matthias
AU - Hemsen, Paul
AU - Klingsieck, Katrin
AU - Kundisch, Dennis
AU - Langendorf, Mike
ID - 1095
T2 - Proceedings of the 25th European Conference on Information Systems (ECIS)
TI - Towards a Lean Approach for Gamifying Education
ER -
TY - CONF
AB - To detect errors or find potential for improvement during the CAD-supported development of a complex technical system like modern industrial machines, the system’s virtual prototype can be examined in virtual reality (VR) in the context of virtual design reviews. Besides exploring the static shape of the examined system, observing the machines’ mechanics (e.g., motor-driven mechanisms) and transport routes for the material transport (e.g., via conveyor belts or chains, or rail-based transport systems) can play an equally important role in such a review. In practice it is often the case, that the relevant information about transport routes, or kinematic properties is either not consequently modeled in the CAD data or is lost during conversion processes. To significantly reduce the manual effort and costs for creating animations of the machines complex behavior with such limited input data for a design review, we present a set of algorithms to automatically determine geometrical properties of machine parts based only on their triangulated surfaces. The algorithms allow to detect the course of transport systems, the orientation of objects in 3d space, rotation axes of cylindrical objects and holes, the number of tooth of gears, as well as the tooth spacing of toothed racks. We implemented the algorithms in the VR system PADrend and applied them to animate virtual prototypes of real machines.
AU - Brandt, Sascha
AU - Fischer, Matthias
AU - Gerges, Maria
AU - Jähn, Claudius
AU - Berssenbrügge, Jan
ID - 16338
SN - 9780791858110
T2 - Volume 1: 37th Computers and Information in Engineering Conference
TI - Automatic Derivation of Geometric Properties of Components From 3D Polygon Models
VL - 1
ER -
TY - THES
AU - Li, Shouwei
ID - 19604
TI - Parallel fixed parameter tractable problems
ER -
TY - CONF
AB - We present an efficient parallel algorithm for the general Monotone Circuit Value Problem (MCVP) with n gates and an underlying graph of bounded genus k. Our algorithm generalizes a recent result by Limaye et al. who showed that MCVP with toroidal embedding (genus 1) is in NC when the input contains a toroidal embedding of the circuit. In addition to extending this result from genus 1 to any bounded genus k, and unlike the work reported by Limaye et al., we do not require a precomputed embedding to be given. Most importantly, our results imply that given a P-complete problem, it is possible to find an algorithm that makes the problem fall into NC by fixing one or more parameters. Hence, we deduce the interesting analogy: Fixed Parameter Parallelizable (FPP) is with respect to P-complete what Fixed Parameter Tractable (FPT) is with respect to NP-complete. Similar work that uses treewidth as parameter was also presented by Elberfeld et al. in [6].
AU - Abu-Khzam, Faisal N.
AU - Li, Shouwei
AU - Markarian, Christine
AU - Meyer auf der Heide, Friedhelm
AU - Podlipyan, Pavel
ID - 143
T2 - Proceedings of the 22nd International Conference on Computing and Combinatorics (COCOON)
TI - The Monotone Circuit Value Problem with Bounded Genus Is in NC
ER -
TY - CONF
AU - Li, Shouwei
AU - Meyer auf der Heide, Friedhelm
AU - Podlipyan, Pavel
ID - 16358
T2 - Algorithms for Sensor Systems, Proceedings of the 12th International Symposium on Algorithms and Experiments for Wireless Sensor Networks (ALGOSENSORS)
TI - The impact of the Gabriel subgraph of the visibility graph on the gathering of mobile autonomous robots
ER -
TY - GEN
AB - We consider a scheduling problem where machines need to be rented from the
cloud in order to process jobs. There are two types of machines available which
can be rented for machine-type dependent prices and for arbitrary durations.
However, a machine-type dependent setup time is required before a machine is
available for processing. Jobs arrive online over time, have machine-type
dependent sizes and have individual deadlines. The objective is to rent
machines and schedule jobs so as to meet all deadlines while minimizing the
rental cost.
Since we observe the slack of jobs to have a fundamental influence on the
competitiveness, we study the model when instances are parameterized by their
(minimum) slack. An instance is called to have a slack of $\beta$ if, for all
jobs, the difference between the job's release time and the latest point in
time at which it needs to be started is at least $\beta$. While for $\beta < s$
no finite competitiveness is possible, our main result is an
$O(\frac{c}{\varepsilon} + \frac{1}{\varepsilon^3})$-competitive online
algorithm for $\beta = (1+\varepsilon)s$ with $\frac{1}{s} \leq \varepsilon
\leq 1$, where $s$ and $c$ denotes the largest setup time and the cost ratio of
the machine-types, respectively. It is complemented by a lower bound of
$\Omega(\frac{c}{\varepsilon})$.
AU - Mäcker, Alexander
AU - Malatyali, Manuel
AU - Meyer auf der Heide, Friedhelm
AU - Riechers, Sören
ID - 16396
T2 - arXiv:1609.01184
TI - Cost-efficient Scheduling on Machines from the Cloud
ER -
TY - CONF
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*2 subgrid. Our model is completely local (no global control, no global coordinates, no compass, no global communication or vision, ...). Each robot can only see its next constant number of left and right neighbors on the chain. This fixed constant is called the 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 FSYNC model. For this problem, we present a gathering algorithm which needs linear time. This result generalizes a result, 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 - 16360
T2 - Proceedings of the 30th International Parallel and Distributed Processing Symposium (IPDPS)
TI - Gathering a Closed Chain of Robots on a Grid
ER -
TY - CONF
AU - von Mammen, Sebastian
AU - Hamann, Heiko
AU - Heider, Michael
ID - 20001
SN - 9781450344913
T2 - ACM Symposium on Virtual Reality Software and Technology (VRST)
TI - Robot Gardens: An Augmented Reality Prototype for Plant-Robot Biohybrid Systems
ER -
TY - CONF
AB - In this paper we consider a strategic variant of the online facility location problem. Given is a graph in which each node serves two roles: it is a strategic client stating requests as well as a potential location for a facility. In each time step one client states a request which induces private costs equal to the distance to the closest facility. Before serving, the clients may collectively decide to open new facilities, sharing the corresponding price. Instead of optimizing the global costs, each client acts selfishly. The prices of new facilities vary between nodes and also change over time, but are always bounded by some fixed value α. Both the requests as well as the facility prices are given by an online sequence and are not known in advance.We characterize the optimal strategies of the clients and analyze their overall performance in comparison to a centralized offline solution. If all players optimize their own competitiveness, the global performance of the system is O(√α⋅α) times worse than the offline optimum. A restriction to a natural subclass of strategies improves this result to O(α). We also show that for fixed facility costs, we can find strategies such that this bound further improves to O(√α).
AU - Drees, Maximilian
AU - Feldkord, Björn
AU - Skopalik, Alexander
ID - 149
T2 - Proceedings of the 10th Annual International Conference on Combinatorial Optimization and Applications (COCOA)
TI - Strategic Online Facility Location
ER -
TY - GEN
ED - Dressler, Falko
ED - Meyer auf der Heide, Friedhelm
ID - 163
TI - Proceedings of the 17th ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc)
ER -
TY - GEN
AB - In this paper, we solve the local gathering problem of a swarm of $n$
indistinguishable, point-shaped robots on a two dimensional grid in
asymptotically optimal time $\mathcal{O}(n)$ in the fully synchronous
$\mathcal{FSYNC}$ time model. Given an arbitrarily distributed (yet connected)
swarm of robots, the gathering problem on the grid is to locate all robots
within a $2\times 2$-sized area that is not known beforehand. Two robots are
connected if they are vertical or horizontal neighbors on the grid. The
locality constraint means that no global control, no compass, no global
communication and only local vision is available; hence, a robot can only see
its grid neighbors up to a constant $L_1$-distance, which also limits its
movements. A robot can move to one of its eight neighboring grid cells and if
two or more robots move to the same location they are \emph{merged} to be only
one robot. The locality constraint is the significant challenging issue here,
since robot movements must not harm the (only globally checkable) swarm
connectivity. For solving the gathering problem, we provide a synchronous
algorithm -- executed by every robot -- which ensures that robots merge without
breaking the swarm connectivity. In our model, robots can obtain a special
state, which marks such a robot to be performing specific connectivity
preserving movements in order to allow later merge operations of the swarm.
Compared to the grid, for gathering in the Euclidean plane for the same robot
and time model the best known upper bound is $\mathcal{O}(n^2)$.
AU - Cord-Landwehr, Andreas
AU - Fischer, Matthias
AU - Jung, Daniel
AU - Meyer auf der Heide, Friedhelm
ID - 16450
T2 - arXiv:1602.03303
TI - Asymptotically Optimal Gathering on a Grid
ER -
TY - CONF
AB - We consider a scheduling problem where machines need to be rented from the cloud in order to process jobs. There are two types of machines available which can be rented for machine-type dependent prices and for arbitrary durations. However, a machine-type dependent setup time is required before a machine is available for processing. Jobs arrive online over time, have machine-type dependent sizes and have individual deadlines. The objective is to rent machines and schedule jobs so as to meet all deadlines while minimizing the rental cost. Since we observe the slack of jobs to have a fundamental influence on the competitiveness, we study the model when instances are parameterized by their (minimum) slack. An instance is called to have a slack of $\beta$ if, for all jobs, the difference between the job's release time and the latest point in time at which it needs to be started is at least $\beta$. While for $\beta series = {LNCS}
AU - Mäcker, Alexander
AU - Malatyali, Manuel
AU - Meyer auf der Heide, Friedhelm
AU - Riechers, Sören
ID - 207
T2 - Proceedings of the 10th Annual International Conference on Combinatorial Optimization and Applications (COCOA)
TI - Cost-efficient Scheduling on Machines from the Cloud
ER -
TY - GEN
ED - Meyer auf der Heide, Friedhelm
ID - 187
IS - 1
T2 - Transactions on Parallel Computing (TOPC)
TI - Introduction to the Special Issue on SPAA 2014
ER -
TY - CONF
AB - In this paper, we solve the local gathering problem of a swarm of n indistinguishable, point-shaped robots on a two dimensional grid in asymptotically optimal time O(n) in the fully synchronous FSYNC time model. Given an arbitrarily distributed (yet connected) swarm of robots, the gathering problem on the grid is to locate all robots within a 2x2- sized area that is not known beforehand. Two robots are connected if they are vertical or horizontal neighbors on the grid. The locality constraint means that no global control, no compass, no global communication and only local vision is available; hence, a robot can only see its grid neighbors up to a constant L1-distance, which also limits its movements. A robot can move to one of its eight neighboring grid cells and if two or more robots move to the same location they are merged to be only one robot. The locality constraint is the significant challenging issue here, since robot move- ments must not harm the (only globally checkable) swarm connectivity. For solving the gathering problem, we provide a synchronous algorithm { executed by every robot { which ensures that robots merge without breaking the swarm con- nectivity. In our model, robots can obtain a special state, which marks such a robot to be performing specific connec- tivity preserving movements in order to allow later merge operations of the swarm. Compared to the grid, for gath- ering in the Euclidean plane for the same robot and time model the best known upper bound is O(n^2).
AU - Cord-Landwehr, Andreas
AU - Fischer, Matthias
AU - Jung, Daniel
AU - Meyer auf der Heide, Friedhelm
ID - 16359
T2 - Proceedings of the 28th ACM Symposium on Parallelism in Algorithms and Architectures (SPAA)
TI - Asymptotically Optimal Gathering on a Grid
ER -
TY - CONF
AB - The self-organizing bio-hybrid collaboration ofrobots and natural plants allows for a variety of interestingapplications. As an example we investigate how robots can beused to control the growth and motion of a natural plant, using LEDs to provide stimuli. We follow an evolutionaryrobotics approach where task performance is determined bymonitoring the plant's reaction. First, we do initial plantexperiments with simple, predetermined controllers. Then weuse image sampling data as a model of the dynamics ofthe plant tip xy position. Second, we use this approach toevolve robot controllers in simulation. The task is to makethe plant approach three predetermined, distinct points in anxy-plane. Finally, we test the evolved controllers in real plantexperiments and find that we cross the reality gap successfully. We shortly describe how we have extended from plant tipto many points on the plant, for a model of the plant stemdynamics. Future work will extend to two-axes image samplingfor a 3-d approach.
AU - Wahby, Mostafa
AU - Hofstadler, Daniel Nicolas
AU - Heinrich, Mary Katherine
AU - Zahadat, Payam
AU - Hamann, Heiko
ID - 19961
SN - 9781509035342
T2 - Proc. of the 10th International Conference on Self-Adaptive and Self-Organizing Systems
TI - An Evolutionary Robotics Approach to the Control of Plant Growth and Motion: Modeling Plants and Crossing the Reality Gap
ER -
TY - CONF
AU - Rybář, Milan
AU - Hamann, Heiko
ID - 20002
SN - 9781450342063
T2 - Proceedings of the Genetic and Evolutionary Computation Conference (GECCO 2016)
TI - Inspiration-Triggered Search: Towards Higher Complexities by Mimicking Creative Processes
ER -
TY - JOUR
AB - Comparative evaluations of peer-to-peer protocols through simulations are a viable approach to judge the performance and costs of the individual protocols in large-scale networks. In order to support this work, we present the peer-to-peer system simulator PeerfactSim.KOM, which we extended over the last years. PeerfactSim.KOM comes with an extensive layer model to support various facets and protocols of peer-to-peer networking. In this article, we describe PeerfactSim.KOM and show how it can be used for detailed measurements of large-scale peer-to-peer networks. We enhanced PeerfactSim.KOM with a fine-grained analyzer concept, with exhaustive automated measurements and gnuplot generators as well as a coordination control to evaluate sets of experiment setups in parallel. Thus, by configuring all experiments and protocols only once and starting the simulator, all desired measurements are performed, analyzed, evaluated, and combined, resulting in a holistic environment for the comparative evaluation of peer-to-peer systems. An immediate comparison of different configurations and overlays under different aspects is possible directly after the execution without any manual post-processing.
AU - Feldotto, Matthias
AU - Graffi, Kalman
ID - 145
IS - 5
JF - Concurrency and Computation: Practice and Experience
TI - Systematic evaluation of peer-to-peer systems using PeerfactSim.KOM
VL - 28
ER -
TY - CONF
AB - Consider a scheduling problem in which a set of jobs with interjob communication, canonically represented by a weighted tree, needs to be scheduled on m parallel processors interconnected by a shared communication channel. In each time step, we may allow any processed job to use a certain capacity of the channel in order to satisfy (parts of) its communication demands to adjacent jobs processed in parallel. The goal is to find a schedule that minimizes the makespan and in which communication demands of all jobs are satisfied.We show that this problem is NP-hard in the strong sense even if the number of processors and the maximum degree of the underlying tree is constant.Consequently, we design and analyze simple approximation algorithms with asymptotic approximation ratio 2-2/m in case of paths and a ratio of 5/2 in case of arbitrary trees.
AU - König, Jürgen
AU - Mäcker, Alexander
AU - Meyer auf der Heide, Friedhelm
AU - Riechers, Sören
ID - 157
T2 - Proceedings of the 10th Annual International Conference on Combinatorial Optimization and Applications (COCOA)
TI - Scheduling with Interjob Communication on Parallel Processors
ER -
TY - GEN
AU - Leder, Lennart
ID - 210
TI - Congestion Games with Mixed Objectives
ER -
TY - GEN
AU - Bülling, Jonas
ID - 5406
TI - Parallelisierung von Algorithmen zur IR-Luftbildanalyse von Laubholzmischbeständen zur Verifizierung der Ausbreitung von Eichenkomplexschäden
ER -
TY - GEN
AU - Kutzias, Damian
ID - 688
TI - Friendship Processes in Network Creation Games
ER -
TY - CONF
AU - Hamann, Heiko
AU - Divband Soorati, Mohammad
ID - 19979
T2 - IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2016)
TI - Robot Self-Assembly as Adaptive Growth Process: Collective Selection of Seed Position and Self-Organizing Tree-Structures
ER -
TY - CONF
AU - Khaluf, Yara
AU - Hamann, Heiko
ID - 20003
T2 - ANTS 2016
TI - On the Definition of Self-organizing Systems: Relevance of Positive/Negative Feedback and Fluctuations
VL - 9882
ER -
TY - CONF
AB - We apply methods of genetic programming to a general problem from software engineering, namely example-based generation of specifications. In particular, we focus on model transformation by example. The definition and implementation of model transformations is a task frequently carried out by domain experts, hence, a (semi-)automatic approach is desirable. This application is challenging because the underlying search space has rich semantics, is high-dimensional, and unstructured. Hence, a computationally brute-force approach would be unscalable and potentially infeasible. To address that problem, we develop a sophisticated approach of designing complex mutation operators. We define ‘patterns’ for constructing mutation operators and report a successful case study. Furthermore, the code of the evolved model transformation is required to have high maintainability and extensibility, that is, the code should be easily readable by domain experts. We report an evaluation of this approach in a software engineering case study.
AU - Kühne, Thomas
AU - Hamann, Heiko
AU - Arifulina, Svetlana
AU - Engels, Gregor
ID - 169
T2 - Proceedings of the 19th European Conference on Genetic Programming (EuroGP 2016)
TI - Patterns for Constructing Mutation Operators: Limiting the Search Space in a Software Engineering Application
ER -
TY - GEN
AU - Handirk, Tobias
ID - 1082
TI - Über die Rolle von Informationen in Verkehrsnetzwerken
ER -
TY - JOUR
AB - We consider online optimization problems in which certain goods have to be acquired in order to provide a service or infrastructure. Classically, decisions for such problems are considered as final: one buys the goods. However, in many real world applications, there is a shift away from the idea of buying goods. Instead, leasing is often a more flexible and lucrative business model. Research has realized this shift and recently initiated the theoretical study of leasing models (Anthony and Gupta in Proceedings of the integer programming and combinatorial optimization: 12th International IPCO Conference, Ithaca, NY, USA, June 25–27, 2007; Meyerson in Proceedings of the 46th Annual IEEE Symposium on Foundations of Computer Science (FOCS 2005), 23–25 Oct 2005, Pittsburgh, PA, USA, 2005; Nagarajan and Williamson in Discret Optim 10(4):361–370, 2013) We extend this line of work and suggest a more systematic study of leasing aspects for a class of online optimization problems. We provide two major technical results. We introduce the leasing variant of online set multicover and give an O(log(mK)logn)-competitive algorithm (with n, m, and K being the number of elements, sets, and leases, respectively). Our results also imply improvements for the non-leasing variant of online set cover. Moreover, we extend results for the leasing variant of online facility location. Nagarajan and Williamson (Discret Optim 10(4):361–370, 2013) gave an O(Klogn)-competitive algorithm for this problem (with n and K being the number of clients and leases, respectively). We remove the dependency on n (and, thereby, on time). In general, this leads to a bound of O(lmaxloglmax) (with the maximal lease length lmax). For many natural problem instances, the bound improves to O(K2).
AU - Abshoff, Sebastian
AU - Kling, Peter
AU - Markarian, Christine
AU - Meyer auf der Heide, Friedhelm
AU - Pietrzyk, Peter
ID - 139
IS - 4
JF - Journal of Combinatorial Optimization
TI - Towards the price of leasing online
ER -
TY - CONF
AB - Efficiently parallelizable parameterized problems have been classified as being either in the class FPP (fixed-parameter parallelizable) or the class PNC (parameterized analog of NC), which contains FPP as a subclass. In this paper, we propose a more restrictive class of parallelizable parameterized problems called fixed-parameter parallel-tractable (FPPT). For a problem to be in FPPT, it should possess an efficient parallel algorithm not only from a theoretical standpoint but in practice as well. The primary distinction between FPPT and FPP is the parallel processor utilization, which is bounded by a polynomial function in the case of FPPT. We initiate the study of FPPT with the well-known k-vertex cover problem. In particular, we present a parallel algorithm that outperforms the best known parallel algorithm for this problem: using O(m) instead of O(n2) parallel processors, the running time improves from 4logn+O(kk) to O(k⋅log3n), where m is the number of edges, n is the number of vertices of the input graph, and k is an upper bound of the size of the sought vertex cover. We also note that a few P-complete problems fall into FPPT including the monotone circuit value problem (MCV) when the underlying graphs are bounded by a constant Euler genus.
AU - Abu-Khzam, Faisal N.
AU - Li, Shouwei
AU - Markarian, Christine
AU - Meyer auf der Heide, Friedhelm
AU - Podlipyan, Pavel
ID - 177
T2 - Proceedings of the 10th International Conference on Combinatorial Optimization and Applications (COCOA)
TI - On the Parameterized Parallel Complexity and the Vertex Cover Problem
ER -
TY - CONF
AB - We study a new class of games which generalizes congestion games and its bottleneck variant. We introduce congestion games with mixed objectives to model network scenarios in which players seek to optimize for latency and bandwidths alike. We characterize the existence of pure Nash equilibria (PNE) and the convergence of improvement dynamics. For games that do not possess PNE we give bounds on the approximation ratio of approximate pure Nash equilibria.
AU - Feldotto, Matthias
AU - Leder, Lennart
AU - Skopalik, Alexander
ID - 209
T2 - Proceedings of the 10th Annual International Conference on Combinatorial Optimization and Applications (COCOA)
TI - Congestion Games with Mixed Objectives
ER -
TY - GEN
AU - Schaefer, Johannes Sebastian
ID - 689
TI - Routing Algorithms on Delayed Networks for Disaster Management Support
ER -
TY - CONF
AB - Defining, measuring, and comparing the quality and efficiency of rendering algorithms in computer graphics is a demanding challenge: quality measures are often application specific and efficiency is strongly influenced by properties of the rendered scene and the used hardware. We survey the currently employed evaluation methods for AQ1 the development process of rendering algorithms. Then, we present our PADrend framework, which supports systematic and flexible development, evaluation, adaptation, and comparison of rendering algorithms, and provides a comfortable and easy-to-use platform for developers of rendering algorithms. The system includes a new evaluation method to improve the objectivity of experimental evaluations of rendering algorithms.
AU - Fischer, Matthias
AU - Jähn, Claudius
AU - Meyer auf der Heide, Friedhelm
AU - Petring, Ralf
ED - Kliemann, Lasse
ED - Sanders, Peter
ID - 16351
T2 - Algorithm Engineering
TI - Algorithm Engineering Aspects of Real-Time Rendering Algorithms
VL - 9220
ER -
TY - CONF
AU - Heinrich, Mary Katherine
AU - Wahby, Mostafa
AU - Divband Soorati, Mohammad
AU - Hofstadler, Daniel Nicolas
AU - Zahadat, Payam
AU - Ayres, Phil
AU - Stoy, Kasper
AU - Hamann, Heiko
ID - 19968
SN - 9781509036516
T2 - Proc. of the 1st International Workshop on Self-Organising Construction (SOCO)
TI - Self-Organized Construction with Continuous Building Material: Higher Flexibility Based on Braided Structures
ER -
TY - GEN
AU - Koepe, Jörn
ID - 5407
TI - Price-Based Allocation Games
ER -
TY - CONF
AU - Valentini, Gabriele
AU - Brambilla, Davide
AU - Hamann, Heiko
AU - Dorigo, Marco
ID - 20004
SN - 0302-9743
T2 - 10th Int. Conf. on Swarm Intelligence, ANTS 2016
TI - Collective Perception of Environmental Features in a Robot Swarm
ER -
TY - JOUR
AB - Abstract—Max-min fairness (MMF) is a widely known approachto a fair allocation of bandwidth to each of the usersin a network. This allocation can be computed by uniformlyraising the bandwidths of all users without violating capacityconstraints. We consider an extension of these allocations byraising the bandwidth with arbitrary and not necessarily uniformtime-depending velocities (allocation rates). These allocationsare used in a game-theoretic context for routing choices, whichwe formalize in progressive filling games (PFGs). We present avariety of results for equilibria in PFGs. We show that these gamespossess pure Nash and strong equilibria. While computation ingeneral is NP-hard, there are polynomial-time algorithms forprominent classes of Max-Min-Fair Games (MMFG), includingthe case when all users have the same source-destination pair.We characterize prices of anarchy and stability for pure Nashand strong equilibria in PFGs and MMFGs when players havedifferent or the same source-destination pairs. In addition, weshow that when a designer can adjust allocation rates, it is possibleto design games with optimal strong equilibria. Some initial resultson polynomial-time algorithms in this direction are also derived.
AU - Harks, Tobias
AU - Höfer, Martin
AU - Schewior, Kevin
AU - Skopalik, Alexander
ID - 159
IS - 4
JF - IEEE/ACM Transactions on Networking
TI - Routing Games With Progressive Filling
ER -
TY - CONF
AU - Macker, Alexander
AU - Malatyali, Manuel
AU - Meyer auf der Heide, Friedhelm
ID - 16364
SN - 9781509021406
T2 - 2016 IEEE International Parallel and Distributed Processing Symposium (IPDPS)
TI - On Competitive Algorithms for Approximations of Top-k-Position Monitoring of Distributed Streams
ER -
TY - THES
AU - Cord Landwehr, Andreas
ID - 154
SN - 978-3-942647-72-4
TI - Selfish Network Creation - On Variants of Network Creation Games
ER -
TY - THES
AU - Drees, Maximilian
ID - 200
TI - Existence and Properties of Pure Nash Equilibria in Budget Games
ER -
TY - JOUR
AU - Hamann, Heiko
AU - Khaluf, Yara
AU - Botev, Jean
AU - Divband Soorati, Mohammad
AU - Ferrante, Eliseo
AU - Kosak, Oliver
AU - Montanier, Jean-Marc
AU - Mostaghim, Sanaz
AU - Redpath, Richard
AU - Timmis, Jon
AU - Veenstra, Frank
AU - Wahby, Mostafa
AU - Zamuda, Aleš
ID - 19969
JF - Frontiers in Robotics and AI
SN - 2296-9144
TI - Hybrid Societies: Challenges and Perspectives in the Design of Collective Behavior in Self-organizing Systems
ER -
TY - JOUR
AU - Dorigo, Marco
AU - Hamann, Heiko
AU - Valentini, Gabriele
AU - Ferrante, Eliseo
ID - 19983
IS - 3
JF - Journal of Autonomous Agents and Multi-Agent Systems
TI - Collective Decision with 100 Kilobots: Speed vs Accuracy in Binary Discrimination Problems
VL - 30
ER -
TY - CONF
AU - Hamann, Heiko
AU - Valentini, Gabriele
AU - Dorigo, Marco
ID - 20000
SN - 0302-9743
T2 - 10th Int. Conf. on Swarm Intelligence, ANTS 2016
TI - Population Coding: A New Design Paradigm for Embodied Distributed Systems
ER -
TY - JOUR
AU - Degener, Bastian
AU - Kempkes, Barbara
AU - Kling, Peter
AU - Meyer auf der Heide, Friedhelm
ID - 16391
JF - ACM Transactions on Parallel Computing
SN - 2329-4949
TI - Linear and Competitive Strategies for Continuous Robot Formation Problems
ER -
TY - GEN
AU - Pfannschmidt, Karlson
ID - 251
TI - Solving the aggregated bandits problem
ER -
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 - 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 - 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 -