On the Progression of Knowledge in Multiagent Systems

ABSTRACT. In a seminal paper, Lin and Reiter introduced the progression of basic action theories in the situation calculus. In this paper, we study the progression of knowledge in multiagent settings, where after actions, an agent updates his beliefs but also updates what he believes other agents know given what has occurred. By appealing to the notion of only knowing, we are able to avoid limitations of earlier work on multiagent progression, and obtain a new general account: we show that after an action, knowledge bases are updated in a Lin and Reiter fashion at every nesting of modalities. Consequently, recent results on the first-order definability of progression carry over to a multiagent setting without too much effort.