An Architecture For Contract-based Communicating Agents

We extend AgentSpeak (L), a belief-desires-intentions architecture, to reason about and plan with contracts between communicating agents. Our architecture is hybrid in the sense that it incorporates both immediate reaction rules and a more complex planning component. We represent contracts as first-class entities to allow the relationships between agents to be specified and developed separately from their built-in capabilities. The agent’s problem-solving ability is augmented by outsourcing tasks to other agents. The contracts are represented as event calculus rules which dictate the evolution of obligations and permissions on the agents concerned. The event calculus is used deductively to infer current and past obligations and permissions, and abductively to make plans to fulfil obligations subject to any restrictions imposed by the contracts.