Bounding trust under uncertain topology information in reputation-based trust systems

Reputation-based trust evaluation relies on the feedback of an entity's past interactions to estimate its trustworthiness for future behavior. Past work commonly assumes that all the information needed in trust evaluation is always available, which, unfortunately, often does not hold in practice, due to a variety of reasons. A key problem is thus to study the quality of trust evaluation in the presence of incomplete information. In this paper, we investigate techniques to bound the output of a trust evaluation under uncertain graph topologies of a reputation system. We present a rigorous formalism of the problem, and establish connections between uncertain topology information and missing feedback information through a property called edge reducibility. We show that the trust bounding problem can be efficiently solved if a trust function is edge reducible.