*) 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. AU - Ziegler, Martin ID - 18280 SN - 0302-9743 T2 - Proc. CiE 2005: New Computational Paradigms TI - Computability and Continuity on the Real Arithmetic Hierarchy and the Power of Type-2 Nondeterminism VL - 3526 ER - TY - CONF AB - 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. AU - Frahling, Gereon AU - Krokowski, Jens ID - 18867 SN - 0302-9743 T2 - Proc. of the 13th Annual European Symposium on Algorithms (ESA 2005) TI - Online Occlusion Culling VL - 3669 ER - TY - CONF AB - 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

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. AU - Bienkowski, Marcin AU - Dynia, Miroslaw AU - Korzeniowski, Miroslaw ID - 18925 SN - 0302-9743 T2 - Proc. of the 22nd Symposium on Theoretical Aspects of Computer Science (STACS) TI - Improved Algorithms for Dynamic Page Migration ER - TY - CHAP AU - Bienkowski, Marcin AU - Korzeniowski, Miroslaw AU - Meyer auf der Heide, Friedhelm ID - 16468 SN - 0302-9743 T2 - Peer-to-Peer Systems IV TI - Dynamic Load Balancing in Distributed Hash Tables ER - TY - CHAP AU - Blömer, Johannes AU - May, Alexander ID - 3006 SN - 0302-9743 T2 - EUROCRYPT 2005 TI - A Tool Kit for Finding Small Roots of Bivariate Polynomials over the Integers ER - TY - CONF AB - 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. AU - Bonorden, Olaf AU - Gehweiler, Joachim AU - Meyer auf der Heide, Friedhelm ID - 16470 SN - 0302-9743 T2 - Proceeedings of 6th International Conference on Parallel Processing and Applied Mathematics (PPAM) TI - A Web Computing Environment for Parallel Algorithms in Java ER - TY - CONF AB - The Hierarchical Layer Graph (HL graph) is a promising network topology for wireless networks with

variable transmission ranges. It was introduced and analyzed by Meyer auf der Heide et al. 2004.

In this paper we present a distributed, localized and resource-efficient algorithm for constructing this graph. The qualtiy of the HL graph depends on the domination radius and the publication radius, which affect the amount of interference in the network. These parameters also determine whether the HL graph is a c-spanner, which implies an energy-efficient topology. We investigate the performance on randomly distributed node sets and show that the restrictions on these parameters derived from a worst case analysis are not so tight using realistic settings.

Here, we present the results of our extensive experimental evaluation, measuring congestion, dilation and energy. Congestion includes the load that is induced by interfering edges. We distinguish between congestion and realistic congestion where we also take the signal-to-interference ratio into account.

Our experiments show that the HL graph contains energy-efficient paths as well as paths with a few number of hops while preserving a low congestion. AU - Rührup, Stefan AU - Schindelhauer, Christian AU - Volbert, Klaus ID - 19835 SN - 0302-9743 T2 - Proc. of 4th International Conference on Ad-Hoc, Mobile & Wireless Networks (ADHOC-NOW 2005) TI - Performance Analysis of the Hierarchical Layer Graph for Wireless Networks VL - 3738 ER - TY - CONF AU - Loeser, Chris AU - Schomaker, Gunnar AU - Brinkmann, André AU - Vodisek, Mario AU - Heidebuer, Michael ID - 19912 SN - 0302-9743 T2 - Proceedings of the 4th International Conference on Networking TI - Content Distribution in Heterogenous Video-on-Demand P2P Networks with ARIMA Forecasts VL - 3421 ER - TY - CONF AU - Böttcher, Stefan AU - Steinmetz, Rita ID - 15156 SN - 0302-9743 T2 - Secure Data Management, Second VLDB Workshop, SDM 2005 TI - Detecting Privacy Violations in Sensitive XML Databases ER - TY - CHAP AU - Bienkowski, Marcin AU - Meyer auf der Heide, Friedhelm ID - 16469 SN - 0302-9743 T2 - Mathematical Foundations of Computer Science 2005 TI - Page Migration in Dynamic Networks ER - TY - CONF AU - Bădoiu, Mihai AU - Czumaj, Artur AU - Indyk, Piotr AU - Sohler, Christian ID - 18768 SN - 0302-9743 T2 - Proc. of the 32nd International Colloquium on Automata, Languages and Programming (ICALP) TI - Facility Location in Sublinear Time ER - TY - CONF AB - 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. AU - Bienkowski, Marcin AU - Byrka, Jarosław ID - 18915 SN - 0302-9743 T2 - Proc. of the 13th Annual European Symposium on Algorithms (ESA 2005) TI - Bucket Game with Applications to Set Multicover and Dynamic Page Migration VL - 3669 ER - TY - CONF AB - 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. AU - Bonorden, Olaf AU - Gehweiler, Joachim AU - Meyer auf der Heide, Friedhelm ID - 16471 SN - 0302-9743 T2 - Proceeedings of 6th International Conference on Parallel Processing and Applied Mathematics (PPAM) TI - Load Balancing Strategies in a Web Computing Environment ER - TY - CHAP AU - Schindelhauer, Christian AU - Voß, Kerstin ID - 19836 SN - 0302-9743 T2 - Proc. of 4th International Conference on Ad-Hoc Networks & Wireless (ADHOC-NOW 2005) TI - Probability Distributions for Channel Utilisation ER - TY - CHAP AU - Ernst, Matthias AU - Jochemsz, Ellen AU - May, Alexander AU - de Weger, Benne ID - 3010 SN - 0302-9743 T2 - EUROCRYPT 2005 TI - Partial Key Exposure Attacks on RSA up to Full Size Exponents ER - TY - CHAP AU - Blömer, Johannes AU - Guajardo, Jorge AU - Krummel, Volker ID - 3011 SN - 0302-9743 T2 - Selected Areas in Cryptography TI - Provably Secure Masking of AES ER - TY - CHAP AU - Blömer, Johannes AU - May, Alexander ID - 3012 SN - 0302-9743 T2 - Public Key Cryptography – PKC 2004 TI - A Generalized Wiener Attack on RSA ER - TY - CONF AB - 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. AU - Bansal, Vikas AU - Meyer auf der Heide, Friedhelm AU - Sohler, Christian ID - 16474 SN - 0302-9743 T2 - 12th Annual European Symposium on Algorithms (ESA 2004) TI - Labeling Smart Dust VL - 3221 ER - TY - CONF AB - 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. AU - Damerow, Valentina AU - Sohler, Christian ID - 18778 SN - 0302-9743 T2 - Proceedings of the 12th European Symposium on Algorithms (ESA'04) TI - Extreme Points Under Random Noise ER -