A Goal Deliberation Strategy for BDI Agent Systems

One aspect of rational behavior is that agents can pursue multiple goals in parallel. Current BDI theory and systems do not provide a theoretical or architectural framework for deciding how goals interact and how an agent can decide which goals to pursue. Instead, they assume for simplicity reasons that agents always pursue consistent goal sets. By omitting this important aspect of rationality, the problem of goal deliberation is shifted from the architecture to the agent programming level and needs to be handled by the agent developer in an error-prone ad-hoc manner. In this paper a goal deliberation strategy called Easy Deliberation is proposed allowing agent developers to specify the relationships between goals in an easy and intuitive manner. It is based on established concepts from goal modeling as can be found in agent methodologies like Tropos and requirements engineering techniques like KAOS. The Easy Deliberation strategy has been realized within the Jadex BDI reasoning engine and is further explained by an example application. To fortify the practical usefulness of the approach it is experimentally shown that the computational cost for deliberation is acceptable and only increases polynomially with the number of concurrent goals.