Formalizing Deductive Coherence: An Application to Norm Evaluation

In this paper we study how agents can autonomously deliberate on norms and cognitions in the context of a normative multiagent system. We propose Thagard’s cognitive theory of coherence as a tool to achieve this autonomous deliberation. Taking a proof-theoretic approach, we first provide a formalization of coherence theory, focusing on a particular type of coherence, namely deductive coherence. We then propose a mechanism to compute coherence values between nodes in a coherence graph, making it fully computational. We further introduce a semantic interpretation of coherence using the notion of degrees of consistency by Ruspini. Finally, we illustrate the formalism in a normative multiagent setting where the norms are established to share a common resource, in this case water. We use graded logic to incorporate uncertainty reasoning in our example.