Sub - delegation and Trust ( Extended

Trust mechanisms can allow an agent to identify the most trustworthy entity to which a task should be delegated. Now this entity may further delegate the task, ultimately resulting in a delegation chain representing the sub-delegation process. Such delegation chains present a problem for current trust evaluation mechanisms, as they typically which reward or penalise a single agent rather than sharing responsibility among all members of the delegation chain. As a result, decisions made on such incorrect trust values would not be optimal, leading to degraded system performance. In this paper we investigate the effects of sub-delegation on a probabilistic trust model and propose a model of weighting trust updates based on shared responsibility. We evaluate this model in the context of a simulated multi-agent system and describe how different weighting strategies can affect probabilistic trust updates when sub-delegation is possible.