Klemens Boehm, Towards Effective and Efficient Behavior-based Trust Models

Trust models have been touted to facilitate cooperation among unknown entities. In our current work, we are interested in behavior-based trust models, i.e., models that derive the trustworthiness of an entity from its behavior in previous interactions. Existing proposals in this field typically feature one specific trust model. Further, various publications exist which have proposed different centrality measures to rank individuals, i.e., compute their reputation based on feedback, and have demonstrated their effectiveness in certain (rather specific) situations. This presentation in turn proposes a framework for behavior-based trust models for open environments with the following distinctive characteristic. Based on a relational representation of behavior-specific knowledge, we propose a trust-policy algebra allowing for the specification of a wide range of trust policies. Since the evaluation of the standing of an entity requires centrality indices, we propose a first-class operator of our algebra for their computation. The presentation concludes with an objective comparison of the effectiveness of the various centrality measures in reputation systems. About the speaker: Klemens Böhm is full professor for computer science at Universität Karlsruhe (TH). Before joining Karlsruhe University in 2004, he has been a professor at Magdeburg University. Prior to that, he has been affiliated with ETH Zurich and GMD Darmstadt. His research interests are distributed information systems, e.g., Peer-to-Peer systems and Grid infrastructures, data management in ubiquitous environments, and data warehousing. Klemens puts much effort in interdisciplinary research and application-oriented projects, currently ranging from biosys-tematics to traffic-data management.