A Modal Logic of Information Change

We study the dynamics of information change, using modal logic as a vehicle. Our semantic perspective is that of a supermodel in which a state represents some agent's information, and the accessibility relations are those of increasing and decreasing knowledge. We concentrate on two specific settings in which an information state consists of all valuations that are models for some propositional formula, or theory, respectively; treating such a set of valuations as an epistemic S5-model, allows us to interpret epistemic formulas in it in the standard fashion. For the validities of one of these two supermodels we provide a Hilbert-style derivation system; our main technical result shows this derivation system to be sound and complete.

• Type: Conference
• Year: 1998
• Where: TARK
• Authors: Joeri Engelfriet, Yde Venema
• Keywords: Automated Reasoning, Epistemic Formulas, Hilbert-style Derivation System, Modal Logic, TARK 1998