Sven Grottke

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In distributed virtual environments (DVEs) the data on which the hosts operate is not consistent at all times. To restore data consistency, the DVE has to employ a consistency algorithm. Unfortunately, all existing DVEs have been built for specific application scenarios, which makes it impossible to compare the consistency algorithms and to choose a(More)
Automated extraction of information from natural language texts remains a largely unsolved problem. Scientific texts in general and mathematical texts in particular, are characterised by the use of complex language constructs, often requiring extensive background knowledge for comprehension. Fortunately, many mathematical texts contain special types of text(More)
We present a rate allocation scheme that pre-computes optimal quantization bucket sizes based on a mathematical model of wavelet transformed natural images prior entropy encoding. We combine our scheme with the JPEG2000 embedded rate-allocator and find in our experiments that it is able to increase JPEG2000 encoding speed by a factor of two without losing(More)
Virtual environments and online games are becoming a major market force. At the same time, the virtual property contained in these environments is being traded for real money and thus attains a real value. Although the legal issues involved with this virtual property have not yet been decided, they will have to be soon. To protect virtual property, virtual(More)
In this paper, we deal with the problem of consistency in distributed systems where hosts have to react to a events in a time span which is less than the network latency. Distributed virtual environments and wireless sensor networks are two typical examples of such systems. In such systems, hosts routinely act while the system is in in inconsistent state in(More)
We investigate the scalability of distributed virtual environments (DVEs) based on a structured peer-to-peer (P2P) overlay. We focus on network load and message routing latency. To this end, we study a prototypical DVE consisting of a simple game scenario and a P2P architecture based on Pastry and Scribe as proposed by Knutsson et al. [1]. Both our(More)
During the past 25 years, a large amount of distributed virtual environment (DVE) systems has been proposed. Each was built to support a single scenario. This not only makes it impossible to rank these various DVEs, it also obscures the effect of each of the algorithms used in those systems. This makes it very hard to select the algorithms for a new(More)
In distributed virtual environments, hosts typically have to react to events within a time span which is less than the network latency. As a consequence, hosts do routinely take actions although the system is in an inconsistent state. This has a noticeable influence on the perceived quality of these actions and their effect on the application. We argue that(More)
We investigate the scalability of distributed virtual environments (DVEs), which are based on a structured peer-to-peer (P2P) overlay. We are interested in the average network load and routing latency and how they depend on the number of hosts in the DVE. To this end, we study a prototypical DVE consisting of a simple game scenario and a P2P architecture(More)
Die automatische Extraktion von Wissen aus natürlichsprachlichen Texten ist eine große technische Herausforderung, die – betrachtet man die Gesamtheit aller möglichen schriftlichen Quellen – heute noch als weitgehend ungelöst gelten muss. Wissenschaftliche und insbesondere mathematische Texte zeichnen sich jedoch durch einen höheren Grad der(More)