Approximate reasoning about actions in presence of sensing and incomplete information

Sensing actions are important for planning with incomplete information. A solution for the frame problem for sensing actions was proposed by Scherl and Levesque. They adapt the possible world model of knowledge to situation calculus. In this paper we propose a high level language in the spirit of the language A, that allows sensing actions. We then present two approximation semantics of this language and their translation to logic programs. Unlike, A, where states are two valued interpretations, and unlike the approach in Scherl and Levesque where states are Kripke models, in our approach states are three valued interpretations.