@phdthesis{17413, author = {{Fischer, Matthias}}, isbn = {{3-935433-73-5}}, publisher = {{Verlagsschriftenreihe des Heinz Nixdorf Instituts, Paderborn}}, title = {{{Design, analysis, and evaluation of a data structure for distributed virtual environments}}}, volume = {{164}}, year = {{2005}}, } @article{17414, abstract = {{Nowadays companies operate in a difficult environment: the dynamics of innovations increase and product life cycles become shorter. Furthermore products and the corresponding manufacturing processes get more and more complex. Therefore, companies need new methods for the planning of manufacturing systems. One promising approach in this context is digital factory/virtual production—the modeling and analysis of computer models of the planned factory with the objective to reduce time and costs. For the modeling and analysis various simulation methods and programs have been developed. They are a highly valuable support for planning and visualizing the manufacturing system. But there is one major disadvantage: only experienced and long trained experts are able to operate with these programs. The graphical user interface is very complex and not intuitive to use. This results in an extensive and error-prone modeling of complex simulation models and a time-consuming interpretation of the simulation results. To overcome these weak points, intuitive and understandable man–machine interfaces like augmented and virtual reality can be used. This paper describes the architecture of a system which uses the technologies of augmented and virtual reality to support the planning process of complex manufacturing systems. The proposed system assists the user in modeling, the validation of the simulation model, and the subsequent optimization of the production system. A general application of the VR- and AR-technologies and of the simulation is realized by the development of appropriate linking and integration mechanisms. For the visualization of the arising 3D-data within the VR- and AR-environments, a dedicated 3D-rendering library is used.}}, author = {{Dangelmaier, Wilhelm and Fischer, Matthias and Gausemeier, Jürgen and Grafe, Michael and Matysczok, Carsten and Mueck, Bengt}}, issn = {{0166-3615}}, journal = {{Computers in Industry}}, pages = {{371--383}}, title = {{{Virtual and augmented reality support for discrete manufacturing system simulation}}}, doi = {{10.1016/j.compind.2005.01.007}}, year = {{2005}}, } @inproceedings{17415, author = {{Fischer, Matthias and Mueck, B. and Mahajan, K. and Kortenjan, M. and Laroque, C. and Dangelmaier, W.}}, booktitle = {{Proceedings of the Winter Simulation Conference}}, isbn = {{0780395190}}, title = {{{Multi-User Support and Motion Planning of Humans and Humans Driven Vehicles in Interactive 3D Material Flow Simulations}}}, doi = {{10.1109/wsc.2005.1574470}}, year = {{2005}}, } @article{18763, abstract = {{Property testing is a relaxation of classical decision problems which aims at distinguishing between functions having a predetermined property and functions being far from any function having the property. In this paper we present a novel framework for analyzing property testing algorithms. Our framework is based on a connection of property testing and a new class of problems which we call abstract combinatorial programs . We show that if the problem of testing a property can be reduced to an abstract combinatorial program of small dimension , then the property has an efficient tester. We apply our framework to a variety of problems. We present efficient property testing algorithms for geometric clustering problems, for the reversal distance problem, and for graph and hypergraph coloring problems. We also prove that, informally, any hereditary graph property can be efficiently tested if and only if it can be reduced to an abstract combinatorial program of small size. Our framework allows us to analyze all our testers in a unified way, and the obtained complexity bounds either match or improve the previously known bounds. Furthermore, even if the asymptotic complexity of the testers is not improved, the obtained proofs are significantly simpler than the previous ones. We believe that our framework will help to understand the structure of efficiently testable properties.}}, author = {{Czumaj, Artur and Sohler, Christian}}, issn = {{0097-5397}}, journal = {{SIAM Journal on Computing}}, number = {{3}}, pages = {{580--615}}, title = {{{Abstract Combinatorial Programs and Efficient Property Testers}}}, doi = {{10.1137/s009753970444199x}}, volume = {{34}}, year = {{2005}}, } @inproceedings{18768, author = {{Bădoiu, Mihai and Czumaj, Artur and Indyk, Piotr and Sohler, Christian}}, booktitle = {{Proc. of the 32nd International Colloquium on Automata, Languages and Programming (ICALP)}}, isbn = {{9783540275800}}, issn = {{0302-9743}}, pages = {{866--877}}, title = {{{Facility Location in Sublinear Time}}}, doi = {{10.1007/11523468_70}}, year = {{2005}}, } @inproceedings{18787, abstract = {{A dynamic geometric data stream consists of a sequence of m insert/delete operations of points from the discrete space {1,..., ∆} d [26]. We develop streaming (1 + ɛ)-approximation algorithms for k-median, k-means, MaxCut, maximum weighted matching (MaxWM), maximum travelling salesperson (MaxTSP), maximum spanning tree (MaxST), and average distance over dynamic geometric data streams. Our algorithms maintain a small weighted set of points (a coreset) that approximates with probability 2/3 the current point set with respect to the considered problem during the m insert/delete operations of the data stream. They use poly(ɛ −1, log m, log ∆) space and update time per insert/delete operation for constant k and dimension d. Having a coreset one only needs a fast approximation algorithm for the weighted problem to compute a solution quickly. In fact, even an exponential algorithm is sometimes feasible as its running time may still be polynomial in n. For example one can compute in poly(log n, exp(O((1+log(1/ɛ)/ɛ) d−1))) time a solution to k-median and k-means [21] where n is the size of the current point set and k and d are constants. Finding an implicit solution to MaxCut can be done in poly(log n, exp((1/ɛ) O(1))) time. For MaxST and average distance we require poly(log n, ɛ −1) time and for MaxWM we require O(n 3) time to do this.}}, author = {{Sohler, Christian and Frahling, Gereon}}, booktitle = {{Proceedings of the 37th ACM Symposium on Theory of Computing (STOC)}}, pages = {{209--217}}, title = {{{Coresets in Dynamic Geometric Data Streams}}}, year = {{2005}}, } @article{18790, author = {{Czumaj, Artur and Sohler, Christian}}, issn = {{0304-3975}}, journal = {{Theoretical Computer Science}}, number = {{1}}, pages = {{37--52}}, title = {{{Testing hypergraph colorability}}}, doi = {{10.1016/j.tcs.2004.09.031}}, volume = {{331}}, year = {{2005}}, } @article{18855, abstract = {{We consider the problem of computing the weight of a Euclidean minimum spanning tree for a set of n points in $\mathbb R^d$. We focus on the setting where the input point set is supported by certain basic (and commonly used) geometric data structures that can provide efficient access to the input in a structured way. We present an algorithm that estimates with high probability the weight of a Euclidean minimum spanning tree of a set of points to within $1 + \eps$ using only $\widetilde{\O}(\sqrt{n} \, \text{poly} (1/\eps))$ queries for constant d. The algorithm assumes that the input is supported by a minimal bounding cube enclosing it, by orthogonal range queries, and by cone approximate nearest neighbor queries. Read More: https://epubs.siam.org/doi/10.1137/S0097539703435297 }}, author = {{Czumaj, Artur and Ergün, Funda and Fortnow, Lance and Magen, Avner and Newman, Ilan and Rubinfeld, Ronitt and Sohler, Christian}}, issn = {{0097-5397}}, journal = {{SIAM Journal on Computing}}, number = {{1}}, pages = {{91--109}}, title = {{{Approximating the Weight of the Euclidean Minimum Spanning Tree in Sublinear Time}}}, doi = {{10.1137/s0097539703435297}}, volume = {{35}}, year = {{2005}}, } @inproceedings{18867, abstract = {{Modern computer graphics systems are able to render sophisticated 3D szenes consisting of millions of polygons. In this paper we address the problem of occlusion culling. Aila, Miettinen, and Nordlund suggested to implement a FIFO buffer on graphics cards which is able to delay the polygons before drawing them. When one of the polygons within the buffer is occluded or masked by another polygon arriving later from the application, the rendering engine can drop the occluded one without rendering, saving important rendering time.
We introduce a theoretical online model to analyse these problems in theory using competitive analysis. For different cost measures addressed we invent the first competitive algorithms for online occlusion culling. Our implementation shows that these algorithms outperform known ones for real 3D scenes as well.}}, author = {{Frahling, Gereon and Krokowski, Jens}}, booktitle = {{Proc. of the 13th Annual European Symposium on Algorithms (ESA 2005)}}, isbn = {{9783540291183}}, issn = {{0302-9743}}, pages = {{758--769}}, publisher = {{Springer}}, title = {{{Online Occlusion Culling}}}, doi = {{10.1007/11561071_67}}, volume = {{3669}}, year = {{2005}}, } @inproceedings{18912, abstract = {{We consider Dynamic Page Migration (DPM) problem, one of the fundamental subproblems of data management in dynamically changing networks. We investigate a hybrid scenario, where access patterns to the shared object are dictated by an adversary, and each processor performs a random walk in X. We extend the previous results of [4]: we develop algorithms for the case where X is a ring, and prove that with high probability they achieve a competitive ratio of O~(min{D−−√4,n}), where D is the size of the shared object and n is the number of nodes in the network. These results hold also for any d-dimensional torus or mesh with diameter at least Ω~(D−−√).}}, author = {{Bienkowski, Marcin and Korzeniowski, Miroslaw}}, booktitle = {{Proc. of the European Conference in Parallel Processing (Euro-Par)}}, isbn = {{9783540287001}}, issn = {{0302-9743}}, title = {{{Dynamic Page Migration Under Brownian Motion}}}, doi = {{10.1007/11549468_105}}, year = {{2005}}, } @inproceedings{18915, abstract = {{We present a simple two-person Bucket Game, based on throwing balls into buckets, and we
discuss possible players' strategies.

We use these strategies to create an approximation algorithm for a generalization of
the well known Set Cover problem, where we need to cover each element by at least $k$ sets.
Furthermore, we apply these strategies to construct a randomized algorithm for Dynamic Page Migration
problem achieving the optimal competitive ratio against an oblivious adversary.}}, author = {{Bienkowski, Marcin and Byrka, Jarosław}}, booktitle = {{Proc. of the 13th Annual European Symposium on Algorithms (ESA 2005)}}, isbn = {{9783540291183}}, issn = {{0302-9743}}, pages = {{815--826}}, publisher = {{Springer }}, title = {{{Bucket Game with Applications to Set Multicover and Dynamic Page Migration}}}, doi = {{10.1007/11561071_72}}, volume = {{3669}}, year = {{2005}}, } @inproceedings{18917, abstract = {{The page migration problem is one of subproblems of data management in networks. It occurs
in a distributed network of processors sharing one indivisible memory page of size D. During runtime,
the processors access a unit of data from the page, and the system is allowed to migrate the page
between the processors. The problem is to compute (on-line) a schedule of page movements
to minimize the total communication cost.

The Dynamic Page Migration problem is an extension to the page migration.
It attempts to model the network dynamics, occurring, for example, in mobile networks.
However, the pace of changes is restricted, i.e. the distances between processors can
change only by a constant per round.

The movement of the nodes induce changes in the communication cost between each pair of nodes,
which is proportional to the distance between them raised to some power $alpha$.
This is typical for mobile wireless networks, where nodes can move with a constant speed,
and the cost of communication is measured in terms of energy used for sending the data.
Thus, by setting $alpha$ equal to the propagation exponent of the medium,
cost minimization becomes minimizing the total energy consumption in the system.

However, as proven in citedynamic-page-migration, if both network mobility and
request sequence are created by an adversary, then the competitive ratio is polynomially large in D and
in the number of the nodes. In our search for a reasonable, close-to-reality model, in this paper we
consider a scenario in which the network mobility is adversarial, but the requests are
generated randomly by a stochastic process. We design an algorithm MTFR for this scenario,
and prove that it is O(1)-competitive, on expectation and with high probability.}}, author = {{Bienkowski, Marcin}}, booktitle = {{Proc. of the 17th ACM Symposium on Parallelism in Algorithms and Architectures (SPAA 2005)}}, location = {{Las Vegas, Nevada, USA}}, pages = {{270--278}}, publisher = {{ACM Press, NY, USA}}, title = {{{Dynamic Page Migration with Stochastic Requests}}}, year = {{2005}}, } @inproceedings{18924, abstract = {{Bluetooth is a wireless communication standard developed for personal area networks (PAN) that gained popularity in the last years. It was designed to connect a few devices together, however nowadays there is a need to build larger networks. Construction and maintenance algorithms have great effect on performance of the network. We present an algorithm based on Cube Connected Cycles (CCC) topology and show how to maintain the network so that it is easily scalable. Our design guarantees good properties such as constant degree and logarithmic dilation. Besides, the construction costs are proven to be at most constant times larger than any other algorithm would need.}}, author = {{Bienkowski, Marcin and Brinkmann, André and Korzeniowski, Miroslaw and Orhan, Orhan}}, booktitle = {{Proceedings of the 4th International Conference on Networking}}, isbn = {{9783540253396}}, issn = {{0302-9743}}, pages = {{413--420}}, publisher = {{Springer}}, title = {{{Cube Connected Cycles Based Bluetooth Scatternet Formation}}}, doi = {{10.1007/978-3-540-31956-6_49}}, volume = {{3420}}, year = {{2005}}, } @inproceedings{18925, abstract = {{The dynamic page migration problem citedynamic-page-migration is defined in
a distributed network of $n$ mobile nodes sharing one indivisible memory page
of size $D$. During runtime, the nodes can both access a unit of data from
the page and move with a constant speed, thus changing the costs of communication.
The problem is to compute online a schedule of page movements
to minimize the total communication cost.

In this paper we construct and analyze the first deterministic algorithm for this problem.
We prove that it achieves an (up to a constant factor) optimal competitive ratio
$O(n cdot sqrtD)$. We show that the randomization of this algorithm
improves this ratio to $O(sqrtD cdot log n)$ (against an oblivious adversary).
This substantially improves an $O(n cdot sqrtD)$ upper bound from citedynamic-page-migration.
We also give an almost matching lower bound of $Omega(sqrtD cdot sqrtlog n)$ for this problem.}}, author = {{Bienkowski, Marcin and Dynia, Miroslaw and Korzeniowski, Miroslaw}}, booktitle = {{Proc. of the 22nd Symposium on Theoretical Aspects of Computer Science (STACS)}}, isbn = {{9783540249986}}, issn = {{0302-9743}}, pages = {{365--376}}, title = {{{Improved Algorithms for Dynamic Page Migration}}}, doi = {{10.1007/978-3-540-31856-9_30}}, year = {{2005}}, } @phdthesis{18967, author = {{Räcke, Harald}}, isbn = {{3-935433-63-8}}, publisher = {{Verlagsschriftenreihe des Heinz Nixdorf Instituts, Paderborn}}, title = {{{Data Management and Routing in General Networks}}}, volume = {{154}}, year = {{2005}}, } @inproceedings{23883, abstract = {{A dynamic geometric data stream is a sequence of m Add/Remove operations of points from a discrete geometric space (1,...,Δ)d [21]. Add(p) inserts a point p from (1,...,Δ)d into the current point set, Remove(p) deletes p from P. We develop low-storage data structures to (i) maintain ε-approximations of range spaces of P with constant VC-dimension and (ii) maintain an ε-approximation of the weight of the Euclidean minimum spanning tree of P. Our data structures use O(log3ε • log3(1/ε) • log(1/ε)/ε2) and O(log (1/δ) • (log Δ/ε)O(d)) bits of memory, respectively (we assume that the dimension d is a constant), and they are correct with probability 1-δ. These results are based on a new data structure that maintains a set of elements chosen (almost) uniformly at random from P.}}, author = {{Frahling, Gereon and Indyk, Piotr and Sohler, Christian}}, booktitle = {{Proceedings of the twenty-first annual symposium on Computational geometry - SCG '05}}, title = {{{Sampling in dynamic data streams and applications}}}, doi = {{10.1145/1064092.1064116}}, year = {{2005}}, } @inbook{17988, author = {{Köhler, Sven and Schindelhauer, Christian and Ziegler, Martin}}, booktitle = {{Fundamentals of Computation Theory}}, isbn = {{9783540281931}}, issn = {{0302-9743}}, title = {{{On Approximating Real-World Halting Problems}}}, doi = {{10.1007/11537311_40}}, year = {{2005}}, } @inbook{17989, author = {{Meer, Klaus and Ziegler, Martin}}, booktitle = {{Fundamentals of Computation Theory}}, isbn = {{9783540281931}}, issn = {{0302-9743}}, title = {{{An Explicit Solution to Post’s Problem over the Reals}}}, doi = {{10.1007/11537311_41}}, year = {{2005}}, } @inproceedings{18280, abstract = {{The sometimes so-called Main Theorem of Recursive Analysis implies that any computable real function is necessarily continuous. We consider three relaxations of this common notion of real computability for the purpose of treating also discontinuous functions f:R->R:
*) non-deterministic computation;
*) relativized computation, specifically given access to oracles like 0' or 0'';
*) encoding input x and/or output y=f(x) in weaker ways according to the Real Arithmetic Hierarchy.
It turns out that, among these approaches, only the first one provides the required power.}}, author = {{Ziegler, Martin}}, booktitle = {{Proc. CiE 2005: New Computational Paradigms}}, isbn = {{9783540261797}}, issn = {{0302-9743}}, pages = {{562--571}}, publisher = {{Springer}}, title = {{{Computability and Continuity on the Real Arithmetic Hierarchy and the Power of Type-2 Nondeterminism}}}, doi = {{10.1007/11494645_68}}, volume = {{3526}}, year = {{2005}}, } @article{18282, author = {{Ziegler, Martin}}, issn = {{0020-7748}}, journal = {{International Journal of Theoretical Physics}}, number = {{11}}, pages = {{2059--2071}}, title = {{{Computational Power of Infinite Quantum Parallelism}}}, doi = {{10.1007/s10773-005-8984-0}}, volume = {{44}}, year = {{2005}}, } @inproceedings{18366, author = {{Dangelmaier, Wilhelm and Mueck, Bengt and Fischer, Matthias and Mahajan, Kiran and Laroque, Christoph}}, booktitle = {{Simulation in wider Europe - 19th European Conference on Modelling and Simulation ECMS 2005}}, pages = {{267--270}}, title = {{{Methods to lead the user to significant processes in a 3D material flow simulation}}}, year = {{2005}}, } @inproceedings{18449, author = {{Loeser, Christoph and Drüke, Isabell and Oesterdiekhoff, Brigitte}}, booktitle = {{IEEE International Conference on Industrial Informatics (INDIN)}}, title = {{{ Glaschick, Rainer: Integrative Approach of Web Services and Universal Plug and Play within an AV Scenario}}}, year = {{2005}}, } @inproceedings{18450, author = {{Oesterdiekhoff, Brigitte}}, booktitle = {{IEEE International Conference on Emerging Technologies and Factory Automation (ETFA)}}, title = {{{Glaschick, Rainer; Service Oriented Interface Design for Embedded Devices}}}, year = {{2005}}, } @inbook{16468, author = {{Bienkowski, Marcin and Korzeniowski, Miroslaw and Meyer auf der Heide, Friedhelm}}, booktitle = {{Peer-to-Peer Systems IV}}, isbn = {{9783540290681}}, issn = {{0302-9743}}, title = {{{Dynamic Load Balancing in Distributed Hash Tables}}}, doi = {{10.1007/11558989_20}}, year = {{2005}}, } @inbook{16469, author = {{Bienkowski, Marcin and Meyer auf der Heide, Friedhelm}}, booktitle = {{Mathematical Foundations of Computer Science 2005}}, isbn = {{9783540287025}}, issn = {{0302-9743}}, title = {{{Page Migration in Dynamic Networks}}}, doi = {{10.1007/11549345_1}}, year = {{2005}}, } @inproceedings{16470, abstract = {{We present a web computing library (PUBWCL) in Java that allows to execute strongly coupled, massively parallel algorithms in the bulk-synchronous (BSP) style on PCs distributed over the internet whose owners are willing to donate their unused computation power. PUBWCL is realized as a peer-to-peer system and features migration and restoration of BSP processes executed on it. The use of Java guarantees a high level of security and makes PUBWCL platform independent. In order to estimate the loss of efficiency inherent in such a Java-based system, we have compared it to our C-based PUB-Library. }}, author = {{Bonorden, Olaf and Gehweiler, Joachim and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceeedings of 6th International Conference on Parallel Processing and Applied Mathematics (PPAM)}}, isbn = {{9783540341413}}, issn = {{0302-9743}}, pages = {{801--808}}, title = {{{A Web Computing Environment for Parallel Algorithms in Java}}}, doi = {{10.1007/11752578_96}}, year = {{2005}}, } @inproceedings{16471, abstract = {{We compare different load balancing strategies for Bulk-Synchronous Parallel (BSP) programs in a web computing environment. In order to handle the influence of the fluctuating available computation power, we classify the external work load. We evaluate the load balancing algorithms using our web computing library for BSP programs in Java (PUBWCL). Thereby we simulated the external work load in order to have repeatable testing conditions. With the best performing load balancing strategy we could save 39% of the execution time averaged and even up to 50% in particular cases.}}, author = {{Bonorden, Olaf and Gehweiler, Joachim and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceeedings of 6th International Conference on Parallel Processing and Applied Mathematics (PPAM)}}, isbn = {{9783540341413}}, issn = {{0302-9743}}, pages = {{839--846}}, title = {{{Load Balancing Strategies in a Web Computing Environment}}}, doi = {{10.1007/11752578_101}}, year = {{2005}}, } @inproceedings{17112, author = {{Bienkowski, Marcin and Damerow, Valentina and Meyer auf der Heide, Friedhelm and Sohler, Christian}}, booktitle = {{Proceedings of the 21st European Workshop on Computational Geometry, Eindhoven, The Netherlands, March 9-11, 2005}}, publisher = {{Technische Universiteit Eindhoven}}, title = {{{Average case complexity of Voronoi diagrams of n sites from the unit cube}}}, year = {{2005}}, } @proceedings{17113, editor = {{Leonardi, Stefano and Meyer auf der Heide, Friedhelm and Wagner, Dorothea}}, location = {{Schloss Dagstuhl, Germany}}, title = {{{Abstracts Collection -- Algorithmic Aspects of Large and Complex Networks}}}, volume = {{05361}}, year = {{2005}}, } @article{15058, author = {{Ziegler, Martin}}, issn = {{0304-3975}}, journal = {{Theoretical Computer Science}}, pages = {{14--26}}, title = {{{Stability versus speed in a computable algebraic model}}}, doi = {{10.1016/j.tcs.2005.09.053}}, year = {{2005}}, } @phdthesis{19616, author = {{Salzwedel, Kay}}, isbn = {{3-935433-62-X}}, publisher = {{Verlagsschriftenreihe des Heinz Nixdorf Instituts, Paderborn}}, title = {{{Data Distribution Algorithms for Storage Networks}}}, volume = {{153}}, year = {{2004}}, } @inproceedings{19692, author = {{Briest, Patrick and Brockhoff, Dimo and Degener, Bastian and Englert, Matthias and Gunia, Christian and Heering, Oliver and Jansen, Thomas and Leifhelm, Michael and Plociennik, Kai and Röglin, Heiko and Schweer, Andrea and Sudholt, Dirk and Tannenbaum, Stefan and Wegener, Ingo}}, booktitle = {{Parallel Problem Solving from Nature - PPSN VIII}}, isbn = {{9783540230922}}, issn = {{0302-9743}}, title = {{{The Ising Model: Simple Evolutionary Algorithms as Adaptation Schemes}}}, doi = {{10.1007/978-3-540-30217-9_4}}, year = {{2004}}, } @inproceedings{19693, author = {{Schweer, Andrea and Leifhelm, Michael and Degener, Bastian and Heering, Oliver and Tannenbaum, Stefan and Röglin, Heiko and Gunia, Christian and Englert, Matthias and Briest, Patrick and Sudholt, Dirk and Brockhoff, Dimo and Wegener, Ingo and Jansen, Thomas and Plociennik, Kai}}, booktitle = {{Parallel Problem Solving from Nature - PPSN VIII}}, title = {{{Experimental Supplements to the Theoretical Analysis of EAs on Problems from Combinatorial Optimization}}}, year = {{2004}}, } @inproceedings{19800, abstract = {{Redundant arrays of independent disks, also called RAID arrays, have gained a wide popularity in the last twenty years. Most of the disks used in the server market are currently based on RAID technology. The primary reason for introducing RAID technology in 1988 has been the fact that large disk systems have become much slower and more expensive than the connection of a large number of inexpensive disks and the use of them as an array. The times seem to repeat themselves. Today, large scale RAID arrays have become incredible big and expensive. It seems that it makes sense to replace them by a collection of smaller and inexpensive arrays of JBODs or mid-ranged RAID arrays. In this paper we will show that combining these systems with state-of-the-art virtualization technology can lead to a system that is faster and less expensive than an enterprise storage system, while being as easy to manage and as reliable. Therefore we will outline the most important features of storage management and compare there realization in enterprise class storage systems and in current and future virtualization environments.}}, author = {{Brinkmann, André and Salzwedel, Kay and Vodisek, Mario}}, booktitle = {{Proceedings of the international workshop on Storage network architecture and parallel I/Os - SNAPI '04}}, pages = {{9--16}}, title = {{{A case for virtualized arrays of RAID}}}, doi = {{10.1145/1162628.1162630}}, year = {{2004}}, } @inproceedings{19807, abstract = {{Wireless connectivity is state of the art for local area networks. Currently, most W-LAN networks rely on a centralized design with access points routing all inner and outbound traffic. These access points are intrinsic communication bottlenecks. Mobile Ad Hoc Networks (MANET) overcome this problem, because every participant works as well as a simple node and as a router. Current MANETs are restricted in scalability, because they rely on flooding mechanisms or complete routing tables. Other approaches, providing better scalability use clustering, yet network performance deteriorates in case of high node mobility. We describe the design of a PAMANET, the Paderborn Mobile Ad Hoc Network, a MANET overcoming these problems providing scalability and reliability in a mobile scenario. When implemented, PAMANET works with standard W-LAN IEEE 802.11 radio devices, provides IPv6 communication interfaces and works on personal computers under a standard Linux distribution. First, we present current routing protocols and classify them with respect to scalability and stability in dynamically evolving MANETs. Then, we discuss related research in the area of distributed hash tables and consistent hashing, used for relieving hot spots in the Web, storage area networks and peerto-peer networks, which inspires the design of PAMANET. PAMANET consists of three main components: First, the embedding of the routing layer into IEEE 802.11 and IPv6 by using techniques used at the ad hoc support library (aslib) by Gupta et al. Second, the routing layer which combines a landmark routing, hierarchical clustering, consistent hashing for providing location dependent addresses and lookup-service for the location of nodes. Third, a peerto-peer data storage system based on egoistic distributed caches enabling hop and traffic efficient data access on replicated data partitions.
The routing layer incorporates a variety of new approaches. Link distances reflect the failure probability of links, which is estimated by the reciprocal age of the link. Then, we combine a landmarking system on this metric with the hierarchical layer graph yielding small landmark addresses and small routing tables. To balance the load of the distributed lookup-service for landmark addresses, a hierarchical weighted consistent hashing scheme is used. This ensures that each node receives an equal part of all landmark addresses. Using these mechanisms (regularly and on demand) PAMANET adjusts IPv6 routing tables such that short stable routes are preferred. For the distribution of control data like landmark information PAMANET uses a message box system interface to provide fast one-hop communication. On top of this system, PAMANET provides a peer-to-peer data storage and lookup system that realizes time, traffic, and load efficient access using egoistic caches and data segmentation strategies.}}, author = {{Schindelhauer, Christian and Böttcher, Stefan and Rammig, Franz}}, booktitle = {{Proceedings of the second international workshop on Mobility management & wireless access protocols}}, isbn = {{1581139209}}, title = {{{The design of PaMaNet the Paderborn mobile ad-hoc network}}}, doi = {{10.1145/1023783.1023807}}, year = {{2004}}, } @inproceedings{19851, abstract = {{The Internet-SCSI protocol [iSCSI] allows a client to interact with a remote SCSI-capable target by means of block-oriented commands encapsulated within TCP/IP packets. Thereby, iSCSI greatly simplifies storage virtualization, since clients can access storage in a unified manner, no matter whether the I/O-path is short or long distance. Intermediate devices located on the path between a client and a target can easily intercept iSCSI sessions and rewrite packets for the sake of load balancing, prefetching, or redundancy, to mention just a few beneficial applications. Within this paper we describe the design and implementation of such an iSCSI capable intermediate device that deploys prefetching strategies in combination with redundant disks to reduce average I/O-latency. Depending on its location within the network, this virtualization and prefetching device can hide wide area access latency and reduce network contention targeting remote SCSI-devices to a large extent.}}, author = {{Bleckmann, Peter and Schomaker, Gunnar and Slowik, Adrian}}, booktitle = {{Proceeding of International Workshop on Storage Network Architecture and Parallel I/O}}, number = {{2}}, pages = {{40--47}}, title = {{{Virtualization with prefetching abilities based on iSCSI}}}, doi = {{10.1145/1162628.1162634}}, year = {{2004}}, } @article{19879, author = {{Klein, Jan and Zachmann, Gabriel}}, journal = {{Computers and Graphics}}, number = {{6}}, pages = {{839--850}}, title = {{{Point Cloud Surfaces using Geometric Proximity Graphs}}}, doi = {{10.1016/j.cag.2004.08.012}}, volume = {{28}}, year = {{2004}}, } @inproceedings{19883, author = {{Klein, Jan and Zachmann, Gabriel}}, booktitle = {{Eurographics Symposium on Point-Based Grahics (SPBG'04)}}, pages = {{131--138}}, title = {{{Proximity Graphs for Defining Surfaces over Point Clouds}}}, year = {{2004}}, } @inproceedings{19889, author = {{Klein, Jan and Zachmann, Gabriel}}, booktitle = {{SIGGRAPH 2004, Sketches}}, title = {{{Nice and Fast Implicit Surfaces over Noisy Point Clouds}}}, year = {{2004}}, } @inproceedings{19891, author = {{Klein, Jan and Zachmann, Gabriel}}, booktitle = {{Computer Graphics Forum (Proceedings of EUROGRAPHICS 2004)}}, pages = {{567--576}}, title = {{{Point Cloud Collision Detection}}}, year = {{2004}}, } @inproceedings{26411, author = {{Volbert, Klaus}}, booktitle = {{Proceedings of the 2004 joint workshop on Foundations of mobile computing - DIALM-POMC '04}}, title = {{{Experimental analysis of adjustable sectorized topologies for static ad hoc networks}}}, doi = {{10.1145/1022630.1022646}}, year = {{2004}}, } @techreport{26992, author = {{Rührup, Stefan and Schindelhauer, Christian}}, title = {{{Traffic and Hop Efficient Position-based Routing using a Cell Structure}}}, year = {{2004}}, } @inproceedings{17346, author = {{Brinkmann, André and Heidebuer, Michael and Meyer auf der Heide, Friedhelm and Rückert, Ulrich and Salzwedel, Kay and Vodisek, Mario}}, booktitle = {{21st {IEEE} Conference on Mass Storage Systems and Technologies / 12th {NASA} Goddard Conference on Mass Storage Systems and Technologies, Greenbelt, Maryland, USA}}, editor = {{Kobler, Ben and Hariharan, P. C.}}, pages = {{153----157}}, publisher = {{IEEE}}, title = {{{V:Drive - Costs and Benefits of an Out-of-Band Storage Virtualization System}}}, year = {{2004}}, } @inproceedings{18777, author = {{Sohler, Christian and Damerow, Valentina}}, booktitle = {{Proceedings of the 20th European Workshop on Computational Geometry (EWCG'04)}}, pages = {{93 -- 96}}, title = {{{Smoothed Number of Extreme Points under Uniform Noise}}}, year = {{2004}}, } @inproceedings{18778, abstract = {{Given a point set P in the d-dimensional unit hypercube, we give upper bounds on the maximal expected number of extreme points when each point is perturbed by small random noise chosen independently for each point from the same noise distribution Δ. Our results are parametrized by the variance of the noise distribution. For large variance we essentially consider the average case for distribution Δ while for variance 0 we consider the worst case. Hence our results give upper bounds on the number of extreme points where our input distributions range from average case to worst case.
Our main contribution is a rather general lemma that can be used to obtain upper bounds on the expected number of extreme points for a large class of noise distributions. We then apply this lemma to obtain explicit bounds for random noise coming from the Gaussian normal distribution of variance σ² and the uniform distribution in a hypercube of side length &epsilon. For these noise distributions we show upper bounds of O( (1/ σ )^d * log^3/2 * d - 1 n ) and O( ( (n log n) / ε )^d/(d+1) ), respectively. Besides its theoretical motivation our model is also motivated by the observation that in many applications of convex hull algorithms the input data is inherently noisy, e.g. when the data comes from physical measurement or imprecise arithmetic is used.}}, author = {{Damerow, Valentina and Sohler, Christian}}, booktitle = {{Proceedings of the 12th European Symposium on Algorithms (ESA'04)}}, isbn = {{9783540230250}}, issn = {{0302-9743}}, title = {{{Extreme Points Under Random Noise}}}, doi = {{10.1007/978-3-540-30140-0_25}}, year = {{2004}}, } @inproceedings{18785, abstract = {{A limiting factor in the performance of a render- ing system is the number of state changes, i.e., changes of the attributes material, texture, shader program, etc., in the stream of rendered primitives. We propose to include a small buffer between appli- cation and graphics hardware in the rendering sys- tem. This pipeline buffer is used to rearrange the incoming sequence of primitives on-line and locally in such a way that the number of state changes is minimized. This method is generic; it can be easily integrated into existing rendering systems. In our experiments a pipeline buffer reduces the number of state changes by an order of magnitude and achieves almost the same rendering time as an optimal, i.e., presorted, sequence without pipeline buffer. Due to its simple structure and its low mem- ory requirements this method can easily be imple- mented in software or even hardware.}}, author = {{Sohler, Christian and Krokowski, Jens and Räcke, Harald and Westermann, Matthias}}, booktitle = {{Proceedings of the Vision, Modeling, and Visualization Conference (VMV 2004)}}, title = {{{Reducing State Changes with a Pipeline Buffer}}}, year = {{2004}}, } @inproceedings{18786, author = {{Sohler, Christian and Czumaj, Artur}}, booktitle = {{Automata, Languages and Programming (ICALP)}}, number = {{1}}, pages = {{396--407}}, title = {{{Sublinear-Time Approximation for Clustering via Random Sampling}}}, year = {{2004}}, } @article{17986, author = {{Ziegler, Martin and Brattka, Vasco}}, journal = {{Theoretical Computer Science}}, number = {{1-3}}, pages = {{187--211}}, title = {{{Computability in linear algebra}}}, doi = {{https://doi.org/10.1016/j.tcs.2004.06.022}}, volume = {{326}}, year = {{2004}}, } @inproceedings{18260, abstract = {{For uniform computability of regular sets in Euclidean space, previous work has identified twelve 'basic' notions, to (pairs of) which many previous notions considered in literature were shown to be equivalent. With respect to those basic notions, we now investigate on the computability of natural OPERATIONS on regular sets: union, intersection, complement, convex hull, image, and pre-image under suitable classes of functions.}}, author = {{Ziegler, Martin}}, booktitle = {{Computability and Complexity in Analysis}}, issn = {{0942-5616}}, number = {{4-5}}, pages = {{392--404}}, title = {{{Computable operators on regular sets}}}, doi = {{10.1002/malq.200310107}}, volume = {{50}}, year = {{2004}}, } @inproceedings{18263, abstract = {{We generalize univariate multipoint evaluation of polynomials of degree n at sublinear amortized cost per point. More precisely, it is shown how to evaluate a bivariate polynomial p of maximum degree less than n, specified by its n^2 coefficients, simultaneously at n^2 given points using a total of O(n^2.667) arithmetic operations. In terms of the input size N being quadratic in n, this amounts to an amortized cost of O(N^0.334) per point.}}, author = {{Nüsken, Michael and Ziegler, Martin}}, booktitle = {{Proc. 12th Annual Symposium on Algorithms (ESA'04)}}, isbn = {{9783540230250}}, issn = {{0302-9743}}, pages = {{544--555}}, publisher = {{Springer}}, title = {{{Fast Multipoint Evaluation of Bivariate Polynomials}}}, doi = {{10.1007/978-3-540-30140-0_49}}, volume = {{3221}}, year = {{2004}}, } @inproceedings{18279, abstract = {{For $c in REAL$, a $c$-spanner is a subgraph of a complete Euclidean graph satisfying that between any two vertices there exists a path of weighted length at most $c$ times their geometric distance. Based on this property to approximate a complete weighted graph, sparse spanners have found many applications, e.g., in FPTAS, geometric searching, and radio networks. For geometric searching, it turned out to suffice whether the radius rather than the length of some path between any two vertices is bounded relatively to their geometric distance; this is the defining property of weak spanners. Finally regarding radio network applications, a power spanner accounts for the total energy afforded for a wireless transmission with the requirement that the sum of the squares of the lengths of some path between any two planar vertices must be bounded relatively to the square of their geometric distance (or higher powers up to 6 or even 8).

While it is known that any $c$-spanner is also both a weak $C_1$-spanner and a $C_2$-power spanner (for appropriate $C_1,C_2$ depending only on $c$ but not on the graph under consideration), we show that the converse fails: There exists a family of $c_1$-power spanners that are no weak $C$-spanners and also a family of weak $c_2$-spanners that are no $C$-spanners for any fixed $C$ (and thus no uniform spanners, either). However the deepest result of the present work reveals that, surprisingly, any weak spanner is also a uniform power spanner. We further generalize the latter notion by considering $(c,delta)$-power spanners where the sum of the $delta$-th powers of the lengths has to be bounded; so $(cdot,2)$-power spanners coincide with the usual power spanners and $(cdot,1)$-power spanners are classical spanners. Interestingly, these $(cdot,delta)$-power spanners form a strict hierarchy where the above results still hold for any $deltageq2$; some even hold for $delta>1$ while counterexamples reveal others to fail for $delta<2$. In fact we show that in general every self-similar curve of fractal dimension $d>delta$ is no $(C,delta)$-power spanner for any fixed $C$. }}, author = {{Schindelhauer, Christian and Volbert, Klaus and Ziegler, Martin}}, booktitle = {{Proc. of 15th Annual International Symposium on Algorithms and Computation (ISAAC'04)}}, isbn = {{9783540241317}}, issn = {{0302-9743}}, pages = {{805--821}}, publisher = {{Springer }}, title = {{{Spanners, Weak Spanners, and Power Spanners for Wireless Networks}}}, doi = {{10.1007/978-3-540-30551-4_69}}, volume = {{3341}}, year = {{2004}}, } @inproceedings{18364, abstract = {{The visualisation of manufacturing-processes assists the user in understanding and analysis. Typically he can move free and unguided in a virtual environment which visualizes the entire process. Thus knowledge and conclusions are to some extend acquired on a random base. This article describes the development of a tool, which enables the user to interactively improve significant production processes in the simulation. He moves in a virtual 3D-environment (walkthrough system) and is able to acquire automatically calculated indications for significant processes. At the same time the simulation considers significant objects in a more detailed way. If the viewer is interested in a significant process, he is automatically guided to the relevant location where he can examine the critical situation by modification of the simulation model.}}, author = {{Mueck, Bengt and Dangelmaier, Wilhelm and Laroque, Christoph and Fischer, Matthias and Kortenjan, Michael}}, booktitle = {{Simulation and Visualisation 2004}}, pages = {{73--83}}, publisher = {{SCS European Publishing House}}, title = {{{Guidance of Users in Interactive 3D-Visualisations of Material Flow Simulations}}}, year = {{2004}}, } @article{18447, author = {{Oesterdiekhoff, Brigitte}}, journal = {{Informatik Spektrum}}, number = {{5}}, pages = {{448--452}}, title = {{{Transcoding von Webinhalten}}}, volume = {{27}}, year = {{2004}}, } @inproceedings{18448, author = {{Oesterdiekhoff, Brigitte}}, booktitle = {{Proceedings of IFIP Working Conference on Distributed and Parallel Embedded Systems (DIPES'04)}}, title = {{{Internet Premium Services for Flexible Format Distributed Devices}}}, year = {{2004}}, } @inproceedings{16474, abstract = {{Given n distinct points p1, p2, ... , pn in the plane, the map labeling problem with four squares is to place n axis-parallel equi-sized squares Q1, ... ,Qn of maximum possible size such that pi is a corner of Qi and no two squares overlap. This problem is NP-hard and no algorithm with approximation ratio better than 1/2 exists unless P = NP [10]. In this paper, we consider a scenario where we want to visualize the information gathered by smart dust, i.e. by a large set of simple devices, each consisting of a sensor and a sender that can gather sensor data and send it to a central station. Our task is to label (the positions of) these sensors in a way described by the labeling problem above. Since these devices are not positioned accurately (for example, they might be dropped from an airplane), this gives rise to consider the map labeling problem under the assumption, that the positions of the points are not fixed precisely, but perturbed by random noise. In other words, we consider the smoothed complexity of the map labeling problem. We present an algorithm that, under such an assumption and Gaussian random noise with sufficiently large variance, has linear smoothed complexity.}}, author = {{Bansal, Vikas and Meyer auf der Heide, Friedhelm and Sohler, Christian}}, booktitle = {{12th Annual European Symposium on Algorithms (ESA 2004)}}, isbn = {{9783540230250}}, issn = {{0302-9743}}, title = {{{Labeling Smart Dust}}}, doi = {{10.1007/978-3-540-30140-0_9}}, volume = {{3221}}, year = {{2004}}, } @inproceedings{16475, author = {{Bienkowski, Marcin and Korzeniowski, Miroslaw and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedings of the sixteenth annual ACM symposium on Parallelism in algorithms and architectures - SPAA '04}}, isbn = {{1581138407}}, title = {{{Fighting against two adversaries}}}, doi = {{10.1145/1007912.1007923}}, year = {{2004}}, } @article{16477, author = {{Meyer auf der Heide, Friedhelm and Schindelhauer, Christian and Volbert, Klaus and Grünewald, Matthias}}, issn = {{1432-4350}}, journal = {{Theory of Computing Systems}}, pages = {{343--370}}, title = {{{Congestion, Dilation, and Energy in Radio Networks}}}, doi = {{10.1007/s00224-004-1124-z}}, year = {{2004}}, } @inproceedings{16480, author = {{Leonardi, S. and Marchetti-Spaccamela, A. and Meyer auf der Heide, Friedhelm}}, booktitle = {{SPAA '04: Proceedings of the sixteenth annual ACM symposium on Parallelism in algorithms and architectures}}, isbn = {{1581138407}}, title = {{{Scheduling against an adversarial network}}}, doi = {{10.1145/1007912.1007936}}, year = {{2004}}, } @article{16399, abstract = {{We present a new data structure for rendering highly complex virtual environments of arbitrary topology. The special feature of our approach is that it allows an interactive navigation in very large scenes (30 GB/400 million polygons in our benchmark scenes) that cannot be stored in main memory, but only on a local or remote hard disk. Furthermore, it allows interactive rendering of substantially more complex scenes by instantiating objects. The sampling process is done in the preprocessing. There, the polygons are randomly distributed in our hierarchical data structure, the randomized sample tree. This tree only uses space that is linear in the number of polygons. In order to produce an approximate image of the scene, the tree is traversed and polygons stored in the visited nodes are rendered. During the interactive walkthrough, parts of the sample tree are loaded from local or remote hard disk. We implemented our algorithm in a prototypical walkthrough system. Analysis and experiments show that the quality of our images is comparable to images computed by the conventional z-buffer algorithm regardless of the scene topology.}}, author = {{Klein, Jan and Krokowski, Jens and Fischer, Matthias and Wand, Michael and Wanka, Rolf and Meyer auf der Heide, Friedhelm}}, issn = {{1054-7460}}, journal = {{Presence: Teleoperators and Virtual Environments}}, pages = {{617--637}}, title = {{{The Randomized Sample Tree: A Data Structure for Interactive Walk-Throughs in Externally Stored Virtual Environments}}}, doi = {{10.1162/1054746043280619}}, year = {{2004}}, } @inproceedings{13071, author = {{Liu Jing, Michelle and Ruehrup, Stefan and Schindelhauer, Christian and Volbert, Klaus and Dierkes, Martin and Bellgardt, Andreas and Ibers, Rüdiger and Hilleringmann, Ulrich}}, booktitle = {{{GOR/NGB Conference Tilburg 2004}}}, title = {{{Sensor Networks with More Features Using Less Hardware}}}, year = {{2004}}, } @article{19726, abstract = {{The Paderborn University BSP (PUB) library is a C communication library based on the BSP model. The basic library supports buffered as well as unbuffered non-blocking communication between any pair of processors and a mechanism for synchronizing the processors in a barrier style. In addition, PUB provides non-blocking collective communication operations on arbitrary subsets of processors, the ability to partition the processors into independent groups that execute asynchronously from each other, and a zero-cost synchronization mechanism. Furthermore, some techniques used in the implementation of the PUB library deviate significantly from the techniques used in other BSP libraries.}}, author = {{Bonorden, Olaf and Juurlink, Bernhardus and von Otte, Ingo and Rieping, Ingo}}, issn = {{0167-8191}}, journal = {{Parallel Computing}}, pages = {{187--207}}, title = {{{The Paderborn University BSP (PUB) library}}}, doi = {{10.1016/s0167-8191(02)00218-1}}, year = {{2003}}, } @article{19785, author = {{Salzwedel, Kay A.}}, isbn = {{9783540008835}}, issn = {{0302-9743}}, journal = {{Algorithms for Memory Hierarchies}}, title = {{{Algorithmic Approaches for Storage Networks}}}, doi = {{10.1007/3-540-36574-5_12}}, volume = {{2625}}, year = {{2003}}, } @inproceedings{19790, abstract = {{The advances in Internet technology have led to tremendous improvements in business, education, and science and have changed the way we think, live, and communicate. Information exchange has become ubiquitous by the possibilities offered through modern technologies. We are able to offer information 24 hours a day through our web sites and can leave messages every time and from anywhere in the world. This change in communication has led to new challenges. Enterprises have to deal with an information amount that doubles every year. The technological foundation to cope with this information explosion is given by Storage Area Networks (SANs), which are able to connect a great number of storage systems over a fast interconnection network. However, to be able to use the benefits of a SAN, an easy-to-use and efficient management support has to be given to the storage administrator. In this paper, we will suggest new storage management concepts and we will introduce a new management environment that is able to significantly reduce management costs and increases the performance and resource utilization of the given SAN infrastructure.}}, author = {{Scheideler, Christian and Salzwedel, Kay and Meyer auf der Heide, Friedhelm and Brinkmann, André and Vodisek, Mario and Rückert, Ulrich}}, booktitle = {{Proceedings of SSGRR 2003}}, title = {{{Storage Management as Means to cope with Exponential Information Growth}}}, year = {{2003}}, } @inproceedings{19806, abstract = {{We try to close the gap between theoretical investigations of wireless network topologies and realistic wireless environments. For point-to-point communication, we examine theoretically well-analyzed sparse graphs, i.e. the Yao-graph, the SparsY-graph, and the SymmY-graph. We present distributed algorithms that can be used to build up these graphs in time $O(log n)$ per node without the use of any geo-graphical positioning system. Our algorithms are based only on local knowledge and local decisions and make use of power control to establish communication links with low energy-cost. We compare these algorithms with respect to congestion, dilation, and energy. For congestion we introduce different measures that allow us to investigate the difference between real-world wireless networks and models for wireless communication at a high level of abstraction. For more realistic simulations we extend our simulation environment SAHNE. We use a realistic transmission model for directed communication that uses sector subdivision. Finally, our experimental results show that our topologies and algorithms work well in a distributed environment and we give some recommendations for the topology control based on our simulations.}}, author = {{Rührup, Stefan and Schindelhauer, Christian and Volbert, Klaus and Grünewald, M.}}, booktitle = {{Proceedings of the International Parallel and Distributed Processing Symposium (IPDPS)}}, isbn = {{0769519261}}, title = {{{Performance of distributed algorithms for topology control in wireless networks}}}, doi = {{10.1109/ipdps.2003.1213107}}, year = {{2003}}, } @misc{19828, author = {{Mahlmann, Peter}}, title = {{{Implementierung und Vergleich von Verfahren zum Information Retrieval im World Wide Web}}}, year = {{2003}}, } @inproceedings{19833, abstract = {{Communication facilities are important in Robotics if several robots have to work together. In this paper, we describe problems and solutions encountered while designing an infrared-based communication device for the mini robot Khepera. In contrast to traditional omnidirectional systems, it features directed, power-variable transmission in eight directions at unit[23.4]kbps up to a range of unit[1m]. It can differentiate incoming data signals from interference from adjacent sectors and can estimate their direction-of-arrival. We model the transmission over the infrared channel and show how interference influences the reception of the data signals. We also describe methods how to reduce these effects. We have tested the performance of the resulted signal processing in a worst case scenario by simulations and in experiments with a prototype implementation. The resulted module is especially suited for experimental evaluation of ad hoc network protocols and for position estimation.}}, author = {{Volbert, Klaus and Grünewald, Matthias and Schindelhauer, Christian and Rückert, Ulrich}}, booktitle = {{Proceedings of the 2nd International Conference on Autonomous Minirobots for Research and Edutainment}}, pages = {{113--122}}, title = {{{Directed power-variable infrared communication for the mini robot Khepera}}}, year = {{2003}}, } @inproceedings{19874, abstract = {{We present a novel framework for hierarchical collision detection that can be applied to virtually all bounding volume (BV) hierarchies. It allows an application to trade quality for speed. Our algorithm yields an estimation of the quality, so that applications can specify the desired quality. In a timecritical system, applications can specify the maximum time budget instead, and quantitatively assess the quality of the results returned by the collision detection afterwards.}}, author = {{Klein, Jan and Zachmann, Gabriel}}, booktitle = {{Proc. 8th International Fall Workshop Vision, Modeling, and Visualization (VMV 2003)}}, pages = {{37--45}}, title = {{{ADB-Trees: Controlling the Error of Time-Critical Collision Detection}}}, year = {{2003}}, } @inproceedings{19900, author = {{Klein, Jan and Zachmann, Gabriel}}, booktitle = {{ Proc. ACM Symposium on Virtual Reality Software and Technology (VRST 2003)}}, pages = {{22--31}}, title = {{{Time-Critical Collision Detection Using an Average-Case Approach}}}, doi = {{10.1145/1008653.1008660}}, year = {{2003}}, } @inproceedings{19952, abstract = {{Graph minors theory, developed by Robertson & Seymour, provides a list of powerful theoretical results and tools. However, the wide spread opinion in Graph Algorithms community about this theory is that it is mainly of theoretical importance. The main purpose of this paper is to show how very deep min-max and duality theorems from Graph Minors can be used to obtain essential speed-up to many known algorithms on different domination problems.}}, author = {{Fomin, Fedor V. and Thilikos, Dimitrios M.}}, booktitle = {{Proceedings of the 14th ACM-SIAM Symposium on Discrete Algorithms (SODA 2003)}}, issn = {{0097-5397}}, title = {{{Dominating Sets in Planar Graphs: Branch-Width and Exponential Speed-Up}}}, doi = {{10.1137/s0097539702419649}}, year = {{2003}}, } @inproceedings{24273, author = {{Terbahl, Martina and Krokowski, Jens}}, booktitle = {{Proceedings of 5. GI-Informatiktage 2003}}, title = {{{Verteiltes Rendern durch dynamische Bildaufteilung}}}, year = {{2003}}, } @inproceedings{26263, author = {{Ziegler, Martin}}, booktitle = {{Proc. 5th Conference on Real Numbers and Computers (RNC5), INRIA}}, pages = {{47--64}}, title = {{{Stability versus Speed in a Computable Algebraic Model}}}, year = {{2003}}, } @inproceedings{26277, author = {{Ziegler, Martin}}, booktitle = {{Computability and Complexity in Analysis}}, pages = {{389--406}}, title = {{{Computable Operators on Regular Sets}}}, volume = {{302-8/2003}}, year = {{2003}}, } @inproceedings{2128, author = {{Damerow, Valentina and Meyer auf der Heide, Friedhelm and Räcke, Harald and Scheideler, Christian and Sohler, Christian}}, booktitle = {{ESA}}, pages = {{161----171}}, publisher = {{Springer}}, title = {{{Smoothed Motion Complexity}}}, doi = {{10.1007/978-3-540-39658-1_17}}, volume = {{2832}}, year = {{2003}}, } @inproceedings{2129, author = {{Awerbuch, Baruch and Brinkmann, André and Scheideler, Christian}}, booktitle = {{ICALP}}, pages = {{1153----1168}}, publisher = {{Springer}}, title = {{{Anycasting in Adversarial Systems: Routing and Admission Control}}}, volume = {{2719}}, year = {{2003}}, } @inproceedings{17423, author = {{Mueck, Bengt and Dangelmaier, Wilhelm and Fischer, Matthias}}, booktitle = {{15th European Simulation Symposium (ESS 2003)}}, pages = {{367--371}}, publisher = {{SCS - Europe}}, title = {{{Components for the Active Support of the Analysis of Material Flow Simulations in a Virtual Environment}}}, year = {{2003}}, } @inproceedings{18791, abstract = {{We consider the problem of finding the weight of a Euclidean minimum spanning tree for a set of n points in ℝd. We focus on the situation when the input point set is supported by certain basic (and commonly used) geometric data structures that can provide efficient access to the input in a structured way. We present an algorithm that estimates with high probability the weight of a Euclidean minimum spanning tree of a set of points to within 1 + ε using only \~{O}(√ poly(1/ε)) queries for constant d. The algorithm assumes that the input is supported by a minimal bounding cube enclosing it, by orthogonal range queries, and by cone approximate nearest neighbors queries.}}, author = {{Magen, Avner and Ergun, Funda and Sohler, Christian and Rubinfeld, Ronitt and Czumaj, Artur and Newman, Ilan and Fortnow, Lance}}, booktitle = {{Proceedings of the 14th ACM-SIAM Symposium on Discrete Algorithms (SODA 2003)}}, isbn = {{0898715385}}, pages = {{813–822}}, title = {{{Sublinear Approximation of Euclidean Minimum Spanning Tree}}}, year = {{2003}}, } @inproceedings{18907, abstract = {{In a (randomized) oblivious routing scheme the path chosen for a request
between a source $s$ and a target $t$ is independent from the current traffic
in the network. Hence, such a scheme consists of probability distributions
over $s-t$ paths for every source-target pair $s,t$ in the network.

In a recent result citeR02 it was shown that for any undirected network
there is an oblivious routing scheme that achieves a polylogarithmic
competitive ratio with respect to congestion. Subsequently, Azar et
al. citeACF+03 gave a polynomial time algorithm that for a given network
constructs the best oblivious routing scheme, i.e. the scheme that guarantees
the best possible competitive ratio.
Unfortunately, the latter result is based on the Ellipsoid algorithm; hence
it is unpractical for large networks.

In this paper we present a combinatorial algorithm for constructing an
oblivious routing scheme that guarantees a competitive ratio of $O(log^4n)$
for undirected networks. Furthermore, our approach yields a proof
for the existence of an oblivious routing scheme with competitive ratio
$O(log^3n)$, which is much simpler than the original proof from citeR02.}}, author = {{Bienkowski, Marcin and Korzeniowski, Miroslaw and Räcke, Harald}}, booktitle = {{Proceedings of the fifteenth annual ACM symposium on Parallel algorithms and architectures - SPAA '03}}, isbn = {{1581136617}}, title = {{{A practical algorithm for constructing oblivious routing schemes}}}, doi = {{10.1145/777412.777418}}, year = {{2003}}, } @inproceedings{18947, abstract = {{In this paper, we define a Petri net model for the network or routing layer of a mobile ad hoc network. Such networks require routing strategies substantially different from those used in static communication networks. The model pre- sented consists of two layers, a location service and a po- sition based routing. Both are described in detail. Our ap- proach considers a very strong definition of fault tolerance thereby improving state-of-the-art ad hoc routing protocols in several respects. Modeling of the communication archi- tecture for mobile ad hoc networks is part of our overall effort towards a design methodology for distributed embed- ded real-time systems including dynamically evolving com- ponents.}}, author = {{Rust, Carsten and Stappert, Friedhelm and Lukovszki, Tamás}}, booktitle = {{7th World Multiconference on Systemics, Cybernetics and Informatics}}, title = {{{A Petri Net Model for the Network Layer of a Mobile Ad Hoc Network Architecture}}}, year = {{2003}}, } @inproceedings{18960, abstract = {{We investigate distributed algorithms for mobile ad hoc networks for moving radio stations with adjustable transmission power in a worst case scenario. We consider two models to find a reasonable restriction on the worst-case mobility. In the pedestrian model we assume a maximum speed $v_max$ of the radio stations, while in the vehicular model we assume a maximum acceleration $a_max$ of the points. Our goal is to maintain persistent routes with nice communication network properties like hop-distance, energy-consumption, congestion and number of interferences. A route is persistent, if we can guarantee that all edges of this route can be uphold for a given time span $Delta$, which is a parameter denoting the minimum time the mobile network needs to adopt changes, i.e. update routing tables, change directory entries, etc. This $Delta$ can be used as the length of an update interval for a proactive routing scheme. We extend some known notions such as transmission range, interferences, spanner, power spanner and congestion to both mobility models and introduce a new parameter called crowdedness that states a lower bound on the number of radio interferences. Then we prove that a mobile spanner hosts a path system that polylogarithmically approximates the optimal congestion. We present distributed algorithms based on a grid clustering technique and a high-dimensional representation of the dynamical start situation which construct mobile spanners with low congestion, low interference number, low energy-consumption, and low degree. We measure the optimality of the output of our algorithm by comparing it with the optimal choice of persistent routes under the same circumstances with respect to pedestrian or vehicular worst-case movements. Finally, we present solutions for dynamic position information management under our mobility models.}}, author = {{Schindelhauer, Christian and Lukovszki, Tamás and Rührup, Stefan and Volbert, Klaus}}, booktitle = {{Proc. of the 15th ACM Symposium on Parallel Algorithms and Architectures (SPAA03)}}, isbn = {{1581136617}}, title = {{{Worst case mobility in ad hoc networks}}}, doi = {{10.1145/777412.777448}}, year = {{2003}}, } @inproceedings{18966, abstract = {{A recent seminal result of Räcke is that for any undirected network there is an oblivious routing algorithm with a polylogarithmic competitive ratio with respect to congestion. Unfortunately, Räcke's construction is not polynomial time. We give a polynomial time construction that guarantees Räcke's bounds, and more generally gives the true optimal ratio for any (undirected or directed) network.}}, author = {{Azar, Yossi and Cohen, Edith and Fiat, Amos and Kaplan, Haim and Racke, Harald}}, booktitle = {{Proceedings of the thirty-fifth ACM symposium on Theory of computing - STOC '03}}, isbn = {{1581136749}}, title = {{{Optimal oblivious routing in polynomial time}}}, doi = {{10.1145/780542.780599}}, year = {{2003}}, } @misc{18982, abstract = {{In dieser Studienarbeit wurde ein System entworfen und implementiert, das der Ausführung paralleler Algorithmen nach dem Bulk-Synchronous Parallel (BSP)-Modell dient. Von der Paderborn University BSP Library (PUB) unterscheidet es sich dadurch, dass es vom Einsatzgebiet her nicht für Parallelrechner konzipiert ist, sondern vielmehr für eine Ansammlung von PCs und Workstations, die über das gesamte Internet verteilt sind.
Gegenüber anderen bekannten Web-Computing Projekten wie z.B. SETI@home oder distributed.net zeichnet sich dieses System dadurch aus, dass nicht Clients von einem zentralen Server "häppchenweise" unabhängige Teilprobleme anfordern und lösen, sondern dass die Clients gemeinsam an einem Problem arbeiten, indem sie nach dem BSP-Modell miteinander kommunizieren und sich synchronisieren.}}, author = {{Gehweiler, Joachim}}, title = {{{Entwurf und Implementierung einer Laufzeitumgebung für parallele Algorithmen in Java}}}, year = {{2003}}, } @article{20435, author = {{Hamann, Heiko}}, journal = {{Complex Systems}}, number = {{3}}, pages = {{263----268}}, title = {{{Definition and Behavior of Langton's Ant in Three Dimensions}}}, volume = {{14}}, year = {{2003}}, } @inproceedings{18196, abstract = {{Fast algorithms for arithmetic on real or complex polynomials are well-known and have proven to be not only asymptotically efficient but also very practical. Based on FAST FOURIER TRANSFORM, they for instance multiply two polynomials of degree up to N or multi-evaluate one at N points simultaneously within quasi-linear time O(N polylog N). An extension to (and in fact the mere definition of) polynomials over fields R and C to the SKEW-field H of quaternions is promising but still missing. The present work proposes three approaches which in the commutative case coincide but for H turn out to differ, each one satisfying some desirable properties while lacking others. For each notion, we devise algorithms for according arithmetic; these are quasi-optimal in that their running times match lower complexity bounds up to polylogarithmic factors.}}, author = {{Ziegler, Martin}}, booktitle = {{Proc. 14th Annual International Symposium on Algorithms and Computation (ISAAC'03)}}, isbn = {{9783540206958}}, issn = {{0302-9743}}, pages = {{705--715}}, title = {{{Quasi-optimal Arithmetic for Quaternion Polynomials}}}, doi = {{10.1007/978-3-540-24587-2_72}}, year = {{2003}}, } @inbook{18258, abstract = {{Multi-evaluation of the Coulomb potential induced by N particles is a central part of N-body simulations. In 3D, known subquadratic time algorithms return approximations up to given ABSOLUTE precision. By combining data structures from Computational Geometry with fast polynomial arithmetic, the present work obtains approximations of prescribable RELATIVE error e>0 in time O(1/e*N*polylog N).}}, author = {{Ziegler, Martin}}, booktitle = {{Lecture Notes in Computer Science}}, editor = {{Dehne, F. and Sack, JR. and Smid, M.}}, isbn = {{9783540405450}}, issn = {{0302-9743}}, publisher = {{Springer}}, title = {{{Fast Relative Approximation of Potential Fields}}}, doi = {{10.1007/978-3-540-45078-8_13}}, volume = {{2748}}, year = {{2003}}, } @inproceedings{18367, abstract = {{Unternehmen operieren zunehmend in einem schwierigen Umfeld: Die Innovationsdynamik nimmt zu; die Produktlebenszyklen werden kürzer; gleichzeitig werden die Produkte komplexer; der harte Wettbewerb zwingt die Unternehmen, auf Marktveränderungen zu reagieren. Aus dieser Entwicklung resultieren hohe Anforderungen an die Gestaltung der Fertigungsprozesse. Im Wesentlichen kommt es darauf an, die Fertigungsprozesse möglichst rasch an die neuen Gegebenheiten anzupassen, bzw. neue Fertigungsprozesse so zu planen, dass sie auf Anhieb die erforderlichen Resultate bringen. Ein wichtiges Mittel hierfür der Einsatz von Materialflusssimulationen. Hierzu ist zunächst die Erstellung eines Simulationsmodells notwendig. Dafür wird in einem ersten Schritt das zu betrachtende System analysiert und ein rechnerinternes Modell erzeugt. Dieses beinhaltet die Modellierung von Funktionen, Prozessen, Verhaltensweisen oder Regeln, die im Modell die tatsächlichen Wirkzusammenhänge im Unternehmen widerspiegeln sollen. Die so modellierten Aspekte sind untereinander so vernetzt, dass alle Funktionen des Modells ein Ganzes ergeben. Für viele Fragenstellungen werden umfangreiche Modelle mit einem komplexen Verhalten benötigt. Andererseits steigt mit zunehmender Größe und Komplexität des Simulationsmodells auch der Modellierungsaufwand, die Fehleranfälligkeit, die Laufzeit und der Interpretationsaufwand bei der Ergebnisauswertung. Fehler bei der Modellbildung führen bei der Simulation zu Fehlinterpretationen und falschen Ergebnissen. Einen wesentlichen Anteil daran hat die Gestaltung der Benutzungsschnittstelle: Das übliche, wenig intuitive WIMP-Interface (Windows, Icons, Mouse, Pointer) erfordert sehr gut geschulte Benutzer, sodass die Erzeugung der meist komplexen Simulationsmodelle mit großen Zeitaufwand verbunden ist. Die Präsentation der Simulationsergebnisse erfolgt in Form von Wertetabellen und zweidimensionalen, abstrakten Darstellungen des Fertigungssystems. Für die Simulationsexperten erscheint dies ausreichend, für ein aus verschiedenen Bereichen und Disziplinen zusammengesetztes Planungsteam ist das aber nicht akzeptabel. So können Fehlinterpretationen aufgrund der unklaren Darstellungen auftreten. Durch eine durchgängige Unterstützung von der Modellierung über die Ausführung bis zur Analyse von Simulationen durch Augmented-Reality und Virtual-Reality werden viele dieser Probleme überwunden aber viele neue Probleme entstehen. Marktgängige Simulatoren unterstützen zwar z.T. schon Virtual Reality; eine durchgängige Simulationsunterstützung wird aber in der Virtuellen Umgebung nicht geboten. Argumented Reality-Komponenten sind bisher nicht bekannt. In diesem Artikel werden nach einer Analyse der benötigten Technologien die Nutzenpotentiale insb. durch den Einsatz von AR ausgelotet. }}, author = {{Fischer, Matthias and Grafe, Michael and Matysczok, Carsten and Mueck, Bengt and Schoo, Michael}}, booktitle = {{Human Aspects in Production Management - Proceedings of the IFIP WG 5.7 Working Conference on Human Aspects in Production Management}}, pages = {{170--177}}, publisher = {{Shaker Verlag}}, title = {{{Virtual and Augmented Reality Support for Discrete Manufacturing System Simulation}}}, volume = {{5}}, year = {{2003}}, } @inproceedings{18372, abstract = {{Simulation und Visualisierung sind anerkannte Mittel zum Verstehen und Analysieren von Fertigungsprozessen. In Visualisierungen von Fertigungsprozessen können Betrachter frei und ungeleitet umherwandern. Erkenntnisse werden so aber eher zufällig erworben. Dieser Artikel skizziert ein System und Methoden, die den Betrachter unterstützen auf auffällige/signifikante Prozesse/ Punkte in Materialflusssimulationen aufmerksam zu werden und diese zu entschärfen. Es wird der Entwurf eines Werkzeugs beschrieben, dass den Betrachter einer Simulation die Möglichkeit bietet, signifikante Produktionsprozesse interaktiv zu verbessern. Der Benutzer wird sich in einer virtuellen 3D-Umgebung (Walkthrough-System) bewegen können und automatisch ermittelte Indizien für signifikante Abläufe erhalten. Zugleich soll die Simulation signifikante Objekte genauer simulieren. Bekundet der Benutzer Interesse an einem signifikanten Prozess, wird er automatisch zu dem jeweiligen Ort geführt werden und dort durch Eingriffe in die Simulation die kritische Situation experimentell untersuchen können. Da der kritische Moment in der Vergangenheit liegt und somit vom Betrachter schon verpasst ist, wird es dem Betrachter möglich sein, die Simulation auf einen Zeitpunkt vor dem Eintreten zurück zu setzen. Die virtuelle Szene (3D-Grafik-Modelle) einer typischen dynamischen Simulationsumgebung ist in der Regel zu komplex, um sie in Echtzeit in einem Walkthrough-System zu visualisieren und darzustellen. Typischerweise werden Approximationsverfahren eingesetzt, um die Komplexität zu reduzieren und ein flüssiges Navigieren des Betrachters zu erlauben. Durch spezifische Simulations-Anforderungen ist bekannt, an welchen Objekten des Simulationsmodells Probleme auftreten; sie sind für den Betrachter wichtig. Die zugehörigen virtuellen 3D-Repräsentanten, können von den Approximationsalgorithmen mit einer besonders hohen Darstellungsqualität dargestellt werden und die übrigen Teile der virtuellen Szene entsprechend vernachlässigt werden. Solche Approximationsalgorithmen und Datenstrukturen nutzen die spezifischen Eigenschaften virtueller Simulationsumgebungen aus, um eine hohe Darstellungsqualität und Darstellungsperformance zu erreichen. }}, author = {{Dangelmaier, Wilhelm and Franke, Werner and Mueck, Bengt and Fischer, Matthias}}, booktitle = {{2. Paderborner Workshop Augmented & Virtual Reality in der Produktentstehung}}, pages = {{141--151}}, title = {{{Komponenten zur aktiven Unterstützung der Analyse von Materialflusssimulationen in virtuellen Umgebungen}}}, volume = {{123}}, year = {{2003}}, } @inproceedings{18374, abstract = {{In der heutigen Zeit operieren Unternehmen zunehmend in einem schwierigen Umfeld: Die Innovationsdynamik nimmt zu und die Produktlebenszyklen werden kürzer. Daraus resultieren hohe Anforderungen an die Planung von Fertigungssysteme. Um diesen Prozess zu unterstützen, sollen die Technologien Augmented Reality und Virtual Reality in einem integrierten System genutzt werden. Dieses System unterstützt den Anwender bei der Modellbildung, der Validierung des Simulationsmodells sowie der folgenden Optimierung des Fertigungssystems. Durch die Entwicklung geeigneter Kopplungs- bzw. Integrationsmechanismen wird eine durchgängige Nutzung der Technologien AR, VR und Simulation realisiert. Die Visualisierung der anfallenden 3D-Daten innerhalb der VR- und ARUmgebungen erfolgt mittels einer 3D-Renderinglibrary, die es durch den Einsatz von neuen entwickelten Verfahren ermöglicht, die verwendeten 3D-Modelle weitgehend automatisiert aus unternehmensinternen 3D-CAD-Modellen zu generieren.}}, author = {{Fischer, Matthias and Grafe, Michael and Matysczok, Carsten and Schoo, Michael and Mueck, Bengt}}, booktitle = {{2. Paderborner Workshop Augmented & Virtual Reality in der Produktentstehung}}, pages = {{153--166}}, publisher = {{Verlagsschriftenreihe des Heinz Nixdorf Instituts, Paderborn}}, title = {{{Planung von komplexen Fertigungssystemen durch Einsatz einer VR/AR-unterstützten Simulation}}}, volume = {{123}}, year = {{2003}}, } @article{18567, author = {{Adler, Micah and Vöcking, Berthold and Sohler, Christian and Räcke, Harald and Sivadasan, Naveen}}, journal = {{Combinatorics, Probability & Computing}}, pages = {{225--244}}, title = {{{Randomized Pursuit-Evasion in Graphs}}}, year = {{2003}}, } @phdthesis{18573, author = {{Sohler, Christian}}, isbn = {{3-935433-28-X}}, publisher = {{Verlagsschriftenreihe des Heinz Nixdorf Instituts, Paderborn}}, title = {{{Property Testing and Geometry}}}, volume = {{119}}, year = {{2003}}, } @article{16481, abstract = {{ZusammenfassungVernetzte Systeme sind zu unverzichtbaren Bestandteilen unseres Umfelds geworden, zum Beispiel als Höchstleistungsrechner, als Kommunikations- und Informationssysteme oder als Planungs- und Steuerungskomponenten von Transport- und Produktionssystemen. Die ständig wachsende Komplexität solcher Systeme stellt Informatiker und Ingenieure vor immer neue Herausforderungen. In diesem Beitrag beschreibe ich die Zielsetzungen und die Struktur des SFB 376 Massive Parallelität: Algorithmen – Entwurfsmethoden – Anwendungen. Als Beispiel für unsere Arbeiten beschreibe ich einen algorithmisch orientierten Forschungszweig, in dem wir, ausgehend von theoretischen Problemen über effiziente Simulationen zwischen parallelen Rechenmodellen, Methoden, Techniken und Implementierungen entwickelt haben, die zu produktnahen Prototypen für die Speichervirtualisierung in verteilten Datenservern führen.}}, author = {{Meyer auf der Heide, Friedhelm}}, issn = {{2196-7032}}, journal = {{it - Information Technology}}, title = {{{Sonderforschungsbereich 376 Massive Parallelität: Algorithmen – Entwurfsmethoden – Anwendungen (Massively Parallel Computing: Algorithms – Design Methods – Applications)}}}, doi = {{10.1524/itit.45.2.108.19606}}, year = {{2003}}, } @article{16482, author = {{Juurlink, Bernhardus and Kolman, Petr and Meyer auf der Heide, Friedhelm and Rieping, Ingo}}, issn = {{1570-8667}}, journal = {{Journal of Discrete Algorithms}}, pages = {{151--166}}, title = {{{Optimal broadcast on parallel locality models}}}, doi = {{10.1016/s1570-8667(03)00023-6}}, year = {{2003}}, } @proceedings{16484, editor = {{Rosenberg, Arnold L. and Meyer auf der Heide, Friedhelm}}, isbn = {{1581136617}}, title = {{{Proceedings of the fifteenth annual ACM symposium on Parallel algorithms and architectures - SPAA '03}}}, doi = {{10.1145/777412}}, year = {{2003}}, } @inproceedings{16720, author = {{Bonorden, Olaf and Bruls, N. and Kastens, U. and Le, D. K. and Meyer auf der Heide, Friedhelm and Niemann, J.-C. and Porrmann, M. and Rückert, U. and Slowik, A. and Thies, M.}}, booktitle = {{28th Annual IEEE International Conference on Local Computer Networks}}, title = {{{A holistic methodology for network processor design}}}, doi = {{10.1109/LCN.2003.1243185}}, year = {{2003}}, } @inproceedings{19727, author = {{Bonorden, Olaf and Meyer auf der Heide, Friedhelm and Wanka, Rolf}}, booktitle = {{Int. Conf. on Parallel and Distributed Processing Techniques and Applications (PDPTA)}}, pages = {{2202--2208}}, title = {{{Composition of Efficient Nested BSP Algorithms: Minimum Spanning Tree Computation as an Instructive Example}}}, year = {{2002}}, } @inproceedings{19850, author = {{Wanka, Rolf}}, booktitle = {{Proc. Workshop on Graph-Theoretic Concepts in Computer Science (WG)}}, isbn = {{9783540003311}}, issn = {{0302-9743}}, pages = {{413--420}}, title = {{{Any Load-Balancing Regimen for Evolving Tree Computations on Circulant Graphs Is Asymptotically Optimal}}}, doi = {{10.1007/3-540-36379-3_36}}, year = {{2002}}, } @inproceedings{19873, abstract = {{We present a new and easy to use framework for navigating through scenes of arbitrary complexity and topology. In the preprocessing, images for discrete viewpoints and viewing directions are rendered and stored on an external volume. During navigation each image can be displayed within a very short time by loading it from the volume. For acceleration, our prefetching strategy loads possibly needed images for the next few frames if the viewer takes a break. The measurements show that we achieve interactive frame rates, whereby the difference between the minimal and maximal display time is very small. Our system works well with scenes modelled by polygons, but also digital photos can easily be used for describing a 3D scene.}}, author = {{Klein, Jan and Krokowski, Jens and Cuntz, Nicolas}}, booktitle = {{Proc. of 4. GI-Informatiktage}}, pages = {{224--229}}, title = {{{Realtime Navigation in Highly Complex 3D-Scenes Using JPEG Compression}}}, year = {{2002}}, } @article{24336, abstract = {{We define here a distributed abstract state machine (DASM) [7] of the network or routing layer of mobile ad hoc networks [13]. Such networks re- quire routing strategies substantially different from those used in static commu- nication networks, since storing and updating large routing tables at mobile hosts would congest the network with administration packets very fast. In [1], the hypercubic location service is presented, which considers a very strong definition of fault-tolerance thereby improving state-of-the-art ad hoc routing protocols in several respects. Our goal in modeling the protocols for the distrib- uted location service and the position based routing is twofold. First, we support the definition and validation of wireless communication protocols and imple- mentations based thereon. Second, we feel that the abstract computation model naturally reflects the layering principle of communication architectures in com- bination with an uncompromisingly local view of the application domain. Thus we can identify fundamental semantic concepts, such as concurrency, reactivity and asynchronism, directly with the related concepts as imposed by the given application context. }}, author = {{ Benczúr, András and Glässer, Uwe and Lukovszki, Tamás}}, journal = {{Proc. of 10th International Workshop on Abstract State Machines, LNCS}}, title = {{{Formal Description of a Distributed Location Service for Mobile Ad Hoc Networks}}}, year = {{2002}}, } @inproceedings{24338, author = {{Grünewald, Matthias and Lukovszki, Tamás and Schindelhauer, Christian and Volbert, Klaus}}, booktitle = {{Proceedings of the 8th International Euro-Par Conference}}, issn = {{0302-9743}}, title = {{{Distributed Maintenance of Resource Efficient Wireless Network Topologies}}}, doi = {{10.1007/3-540-45706-2_134}}, year = {{2002}}, } @inproceedings{26412, author = {{Volbert, Klaus}}, booktitle = {{Proceedings 10th Euromicro Workshop on Parallel, Distributed and Network-based Processing}}, title = {{{A simulation environment for ad hoc networks using sector subdivision}}}, doi = {{10.1109/empdp.2002.994324}}, year = {{2002}}, } @inproceedings{2136, author = {{Brinkmann, André and Salzwedel, Kay and Scheideler, Christian}}, booktitle = {{SPAA}}, pages = {{53----62}}, title = {{{Compact, adaptive placement schemes for non-uniform requirements}}}, year = {{2002}}, }