Implementation of Normative Practical Reasoning with Durative Actions

Abstract

Autonomous agents operating in a dynamic environment need constantly to reason about actions in pursuit of their goals, while taking into consideration possible norms imposed on those actions. Normative practical reasoning supports agents decision making about what is best for an agent to do in a given situation. What makes practical reasoning challenging is the conflict between goals that the agent is pursuing and the norms that the agent is trying to uphold. We offer a formal model that allows the agents to plan for conflicting goals and norms in presence of durative actions that can be executed concurrently. We compare plans based on decision-theoretic notions (i.e. utility) such that the utility gain of goals and utility loss of norm violations are the basis of this comparison. The set of optimal plans consists of plans that maximise the overall utility, each of which can be chosen by the agent to execute. The formal model is implemented computationally using answer set programming, which in turns permits the statement of the problem in terms of a logic program that can be queried for solutions with specific properties. We demonstrate how a normative practical reasoning problem can be mapped into an answer set program such that the optimal plans of the former can be obtained as the answer sets of the latter.