Local Perspectives on Actions

Giving an account of agents acting in the world—sensing, planning, communicating, doing—requires a coordinated account of, at least, three different kinds of action: ontic, epistemic, and communicative, which focus, respectively, on fact, knowledge and communication. In this note we are concerned primarily with ontic actions. The motivating example is the STRIPS approach to the frame problem, where actions are restricted to change only specified fluents. We present an algebraic setting for ontic actions modeled as relations describing controlled state change. We start from a standard model that encodes STRIPS updates to address the frame problem in logical terms. This model is a system, in the sense of Resende and Baltag. We describe a structure that introduces a notion of local perspective or experiment. This provides a novel treatment of causal relations (which are closely related to integrity constraints and domain axioms in the AI-planning literature). We show how this local structure arises naturally from the semantic structure of the set of possible states, and suggest that it may also help in modeling agents with different perspectives.