*) 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 -