Iterated belief update based on ordinal conditional functions

Abstract

Proposes a faithful assignment function to construct W. Spohn's (1988) ordinal conditional functions (OCFs) that reflect ordinals in the current epistemic state represented by an OCF as long as possible. We also propose a composition schema for OCFs that construct a new OCF which satisfies postulates for updating and erasure in the AGM (Alchourron, Ga/spl uml/rdenfors & Makinson, 1985) paradigm. The faithful assignments for OCFs and the composition provide useful devices to represent iterated belief updates.