Abstract
This paper shows that there is a direct connection between dialogues and belief sharing. This connection is shown by proving a correspondence between observational equivalence between dialogues and epistemic bisimulation between Hyper-Discourse Representation Structures (Hyper-DRS) constructed from dialogues. An observational equivalence between dialogues is defined by a kind of similarity of resulting shared beliefs of the dialogues. The theory of Hyper-DRSs is defined by extending Kamp's Discourse Representation Theory (Kamp and Reyle 1993), a formal semantics of discourse or a dynamic semantics, which is exploiting the theory of hypersets (Aczel 1987;Barwise and Moss 1996) in order to solve the problem of the definition, formation and revision of circular objects like shared beliefs.
