Christian von der Weth

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Distributed NoSQL systems aim to provide high availability for large volumes of data but lack the inherent support of complex queries often required by overlying applications. Common solutions based on inverted lists for single terms perform poorly in large-scale distributed settings. The authors thus propose a multiterm indexing technique that can store(More)
Trust models have been touted to facilitate cooperation among unknown entities. Existing behavior-based trust models typically include a fixed evaluation scheme to derive the trustworthiness of an entity from knowledge about its behavior in previous interactions. This paper in turn proposes a framework for behavior-based trust models for open environments(More)
Structured P2P systems in the form of distributed hash tables (DHT) are a promising approach for building massively distributed data management platforms. However, for many applications the supported key lookup queries are not sufficient. Instead, techniques for managing and querying (relational) structured data are required. In this paper, we argue that in(More)
The investigation of the browsing behavior of users has been a topic of active research since the Web started. However, new online services changed the meaning behind "browsing the Web" and require a fresh look at the problem. Platforms such as YouTube or last. Fm have started to replace the traditional media channels (cinema, television, radio) and media(More)
Finding relevant and reliable information on the web is a non-trivial task. While internet search engines do find correct web pages with respect to a set of keywords, they often cannot ensure the relevance or reliability of their content. An emerging trend is to harness internet users in the spirit of Web 2.0, to discern and personalize relevant and(More)
NoSQL systems are more and more deployed as back-end infrastructure for large-scale distributed online platforms like Google, Amazon or Facebook. Their applicability results from the fact that most services of online platforms access the stored data objects via their primary key. However, NoSQL systems do not efficiently support services referring more than(More)
Location-based services gained much popularity through providing users with helpful information with respect to their current location. As a recent trend, virtual location-based services consider webpages or sites associated as 'virtual locations' that online users can visit. The presence of links between virtual locations and the corresponding physical(More)
Despite the services of sophisticated search engines, there are interesting information sources which are useful but largely inaccessible to current web users. These sources are often ad-hoc, location-specific and only useful for users over short periods of time, or relate to tacit knowledge of users or crowds. The solution presented in this paper(More)
Peer-to-Peer data structures (P2P data structures) let a large number of anonymous peers share the data-management workload. A common assumption behind such systems is that peers behave cooperatively. But as with many distributed systems where participation is voluntary, and the participants are not clearly observable, unreliable behavior is the dominant(More)