Ron Petrick's Webpages

Book chapter

Knowledge, Action, and Cartesian Situations in the Situation Calculus, R. Petrick, in Gerhard Lakemeyer and Sheila A. McIlraith (eds.), Knowing, Reasoning, and Acting: Essays in Honour of Hector J. Levesque, College Publications, 2011.

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Abstract

We formalize the notion of a Cartesian situation in the situation calculus, a property that imposes strong structural conditions on the configuration of a set of possible worlds. Focusing on action theories that use the standard Scherl and Levesque account of knowledge and action, we show how Cartesian situations give rise to a set of decomposition properties for simplifying epistemic formulae (in particular, certain disjunctive and existentially quantified formulae) into equivalent components that only mention fluent literals. Moreover, we describe certain expressive classes of action theories that preserve the Cartesian property through action. This work offers the possibility of identifying action theories that can be compiled into alternative accounts of knowledge with similar representational restrictions, but without possible worlds.