Formalizing sensing actions - A transition function based approach

In presence of incomplete information about the world we need to distinguis h between the state of the world and the state of the agent's knowledge abo ut the world. In such a case the agent may need to have at its disposal sen sing actions that change its state of knowledge about the world and may nee d to construct more general plans consisting of sensing actions and conditi onal statements to achieve its goal. In this paper we first develop a high- level action description language that allows specification of sensing acti ons and their effects in its domain description and allows queries with con ditional plans. We give provably correct translations of domain description in our language to axioms in first-order logic, and relate our formulation to several earlier formulations in the literature. We then analyze the sta te space of our formulation and develop several sound approximations that h ave much smaller state spaces. Finally we define regression of knowledge fo rmulas over conditional plans. (C) 2001 Elsevier Science B.V. All rights re served.