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Karl Aberer

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Publications associées (297)

Leveraging Social Networks for Increased BitTorrent Robustness

Zoran Despotovic, Karl Aberer, Wojciech Galuba

In peer-to-peer content delivery systems, such as BitTorrent, there may exist nodes that are non-cooperative and do not contribute their upload bandwidth to the system while still downloading content from others. The current widely used countermeasures aga ...

IEEE2010

Using identity premium for cooperation enforcement and whitewashing prevention in rational environments

Karl Aberer, Hung Le Vu

One fundamental issue in existing reputation mechanisms, particularly those in open and decentralized multi-agent systems, is whitewashing attacks by rational providers. If identities are cheap, it is beneficial for a provider to simply defect when selling ...

2010

Towards Probabilistic Estimation of Quality of Online Services

Karl Aberer

Accurate estimation of quality of online services is both an important and difficult problem, since a service has many interdependent quality attributes influenced by several contextual factors. It is even more challenging as quality ratings come from sour ...

IEEE2009

Environmental Monitoring 2.0

Karl Aberer, Guillermo Barrenetxea Kobas, Marc Parlange, Ali Salehi, Sebastian Michel, Mathias Thierry Pierre Bavay

A sensor network data gathering and visualization infrastructure is demonstrated, comprising of Global Sensor Networks (GSN) middleware and Microsoft SensorMap. Users are invited to actively participate in the process of monitoring real-world deployments a ...

ICDE2009

Self-organized fault-tolerant routing in peer-to-peer overlays

Zoran Despotovic, Karl Aberer, Wojciech Galuba

In sufficiently large heterogeneous overlays message loss and delays are likely to occur. This has a significant impact on overlay routing, especially on longer paths. The existing solutions to this problem rely on message redundancy to mask the loss and d ...

IEEE2009

Towards Access Control Aware P2P Data Management Systems

Karl Aberer, Zoltán Miklós

2P data management systems provide a scalable alternative to centralized architectures. Their adoption, however, is limited by the lack of possibility to control the access to the resources stored in the system. We address this problem in the case of struc ...

ACM2009

ProtoPeer: A P2P Toolkit Bridging the Gap Between Simulation and Live Deployment

Zoran Despotovic, Karl Aberer, Wojciech Galuba

2009

idMesh: graph-based disambiguation of linked data

Philippe Cudré-Mauroux, Karl Aberer, Michael Jost, Parisa Haghani

We tackle the problem of disambiguating entities on the Web. We propose a user-driven scheme where graphs of entities -- represented by globally identifiable declarative artifacts -- self-organize in a dynamic and probabilistic manner. Our solution has the ...

ACM2009

Query-Driven Indexing for Scalable Peer-to-Peer Text Retrieval

Martin Rajman, Karl Aberer, Gleb Skobeltsyn, Vinh Toan Luu, Ivana Podnar

We present a query-driven algorithm for the distributed indexing of large document collections within structured P2P networks. To cope with bandwidth consumption that has been identified as the major problem for the standard P2P approach with single term i ...

2009

Enabling Secure Secret Sharing in Distributed Online Social Networks

Sonja Buchegger, Karl Aberer, Anwitaman Datta

We study a new application of threshold-based secret sharing in a distributed online social network (DOSN), where users need a means to back up and recover their private keys in a network of untrusted servers. Using a simple threshold-based secret sharing ...

Ieee Computer Soc Press, Customer Service Center, Po Box 3014, 10662 Los Vaqueros Circle, Los Alamitos, Ca 90720-1264 Usa2009

Evaluating Top-k Queries over Incomplete Data Streams

Karl Aberer, Parisa Haghani, Sebastian Michel

We study the problem of continuous monitoring of top-k queries over multiple non-synchronized streams. Assuming a sliding window model, this general problem has been a well addressed research topic in recent years. However, most approaches assume the strea ...

2009

Towards Integrated and Efficient Scientific Sensor Data Processing: A Database Approach

Jie Wu, Karl Aberer

In this work, we focus on managing scientific environmental data, which are measurement readings collected from wireless sensors. In environmental science applications, raw sensor data often need to be validated, interpolated, aligned and aggregated before ...

2009

Query-Driven Indexing for Scalable Peer-to-Peer Text Retrieval

Martin Rajman, Karl Aberer, Gleb Skobeltsyn, Vinh Toan Luu, Ivana Podnar

In this paper, we present a query-driven indexing/retrieval strategy for efficient full text retrieval from large document collections distributed within a structured P2P network. Our indexing strategy is based on two important properties: (1) the generate ...

2009

Dynamic Cost-Efficient Replication in Data Clouds

Nicolas Bonvin, Karl Aberer

Hardware failures in current data centers are common partly due to the higher data scales supported. Data replication is the common approach for improving availability. However, mostly static replication approaches have been proposed, i.e. the number of re ...

2009

Synergies of different reputation systems: challenges and opportunities

Karl Aberer

Reputation is a well established means to determine trustworthiness in online systems in various contexts, e.g. online transactions, product recommendation, e-mail spam fighting, etc. However, typically these reputation systems are "closed" outside of the ...

IEEE Computer Society2009

Knowing When to Slide: Efficient Scheduling for Sliding Window Processing

Karl Aberer, Ali Salehi, Sebastian Michel, Mehdi Riahi

We consider sliding window query execution scheduling in stream processing engines. Sliding windows are an essential building block to limit the query focus at a particular part of the stream, based either on value count or time ranges. These so called sli ...

IEEE Computer Society2009

Distributed Similarity Search in High Dimensions Using Locality Sensitive Hashing

Karl Aberer, Parisa Haghani, Sebastian Michel

In this paper we consider distributed K-Nearest Neighbor (KNN) search and range query processing in high dimensional data. Our approach is based on Locality Sensitive Hashing (LSH) which has proven very efficient in answering KNN queries in centralized set ...

2009

Scalable Delivery of Stream Query Result

Karl Aberer, Ali Salehi

Continuous queries over data streams typically produce large volumes of result streams. To scale up the system, one should carefully study the problem of delivering the result streams to the end users, which, unfortunately, is often over-looked in existing ...

VLDB2009

Processing Publish/Subscribe Queries over Distributed Data Streams

Karl Aberer, Alexandre Herrmann, Oana Anca Jurca, Sebastian Michel

2009

Neighborhood-based Tag Prediction

Philippe Cudré-Mauroux, Karl Aberer, Adriana Budura, Sebastian Michel

We consider the problem of tag prediction in collaborative tagging systems where users share and annotate resources on the Web. We put forward HAMLET, a novel approach to automatically propagate tags along the edges of a graph which relates similar documen ...

2009

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