Tracing Dependencies of Strategy Selections in Agent Design

Dung N. Lam, K. Suzanne Barber

Abstract: Given the diverse multi-agent system (MAS) implementations developed for various domains, there has been a lack of a comprehensive method for analyzing and evaluating the assortment of MAS architectures and technologies resident in those architectures. With a formal method to investigate agent architectures, MAS designers can answer 1) how performance criteria affect design decisions, 2) how design decisions affect MAS behavior, and 3) which combinations of design decisions are best suited for the application. This research proposes that the first step in answering these questions is to decompose an agent into its core competencies (CC), which define the major functionalities of an agent. Some example core competencies include agent organization (AO), plan generation (PG), task allocation (TA), plan integration (PI), plan execution (PE), world modeling, communication, actuation, and perception (Barber, Liu, and Han 1999). CCs affect the behavior of the agent and of the system.= For each CC, the designer chooses to implement a core competency strategy from a library of existing strategies. With each design decision, the number of possible strategy combinations decreases due to the dependencies among strategies across CCs. In solving a given problem, an agent coordinates itself with other agents in the system to organize and to create a plan and/or reactively generate actions that leads to a solution. The agent uses its chosen agent organization, which defines how agents interact with each other, to manage the agents during the planning process. First, the agent works alone or cooperates with other agents in PG. Next, in TA, those plans and subtasks are distributed to the appropriate agents. Finally, in PI, the agents’ schedules are combined according to the chosen strategy, which results in task-coordinated agents. After planning, the agents must monitor the execution of the subtasks and make any necessary adjustments. Each CC strategy has dependencies based on its demands on the functionality of other CCs (e.g., a market AO demands that TA be composed of proposals, bids, and agreements). Additionally, the selection of a CC strategy is dictated by dependencies among variables (factors and