A Dynamic Logic of Observation and Access First Draft
Tomohiro Hoshi, Eric Pacuit · 2009
Reasoning about rational agents interacting over time is a central topic in many areas of philosophy, computer science and economics. An important challenge for the logician is to account for the many dynamic processes that govern the agents’ interaction over time. Inference, observation and communication are all examples of such processes that are the focus of current logics of informational update and belief revision (see, for example, van Benthem, 1996; van Ditmarsch et al., 2007; Parikh and Ramanujam, 2003). A recurring issue in any formal model that represents agents’ informational attitudes over time is how to account for the fact that the agents are limited in their access to the available inference steps, possible observations and available messages. This may be because the agents are not logically omniscient and so do not have unlimited reasoning ability. But it can also be because the agents are following a predefined protocol that explicitly limits statements available for observation and/or communication. Within the broad literature on epistemic logic, there are a variety of alternative accounts that making precise a notion of an agent’s “limited access”. An early approach of Fagin and