The Bases of Effective Coordination in Decentralized Multiagent Systems

Coordination is a recurring theme in multiagent systems design. We consider the problem of achieving coordination in a system where the agents make autonomous decisions based solely on local knowledge. An open theoretical issue is what goes into achieving effective coordination? There is some folklore about the importance of the knowledge held by the different agents, but the rest of the rich agent landscape has not been explored in depth. The present paper seeks to delineate the different components of an abstract architecture for agents that influence the effectiveness of coordination. Specifically, it proposes that the extent of the choices available to the agents as well as the extent of the knowledge shared by them are both important for understanding coordination in general. These lead to a richer view of coordination that supports a more intuitive set of claims. This paper supports its conceptual conclusions with experimental results based on simulation. 1 Introduction The coor..

Handling Semantic Exceptions in the Large: A Multiagent Approach

We consider semantic exceptions, which arise when a task yields results that are incorrect, inconsistent with related tasks, or incomplete. Semantic exceptions are especially prominent in the large, i.e., when we construct and execute a workflow. A workflow is a composite computation with several interoperating components and interacting processes. Detecting and resolving semantic exceptions is critical to the functioning of a workflow, especially when its member activities are autonomous, heterogeneous, long-lived, and interact in subtle ways. Unfortunately, present workflow techniques offer little support for exceptions. For modeling, they provide few abstractions beyond activity charts. For enactment, they are not flexible enough to allow a component to detect and resolve semantic exceptions properly. We describe a multiagent approach for handling semantic exceptions. Our approach is based on high-level abstractions such as commitments, a process metamodel that accommodates commitm..