Giacomo Bonanno
Working Papers

Giacomo Bonanno,   A Kripke-Lewis semantics for belief update and belief revision.


We provide a new characterization of both belief update and belief revision in terms of a Kripke-Lewis semantics. We consider frames consisting of a set of states, a Kripke belief relation and a Lewis selection function. Adding a valuation to a frame yields a model. Given a model and a state, we identify the initial belief set K with the set of formulas that are believed at that state and  we identify either the updated belief set or the revised belief set, prompted by the input represented by formula A, as the set of formulas that are the consequent of conditionals that (1) are believed at that state and (2) have A as antecedent. We show that this class of models characterizes both the Katsuno-Mendelzon (KM) belief update functions and the AGM belief revision functions, in the following sense: (1) each model gives rise to a partial belief function that can be completed into a full KM/AGM update/revision function, and (2) for every KM/AGM update/revision function there is a model whose associated belief function coincides with it. The difference between update and revision can be reduced to two semantic properties that appear in a stronger form in revision relative to update, thus confirming the finding by Peppas et al. (1996) that, "for a fixed theory K, revising K is much the same as updating K". 

                             To download the file in pdf format click hereUpdRev.pdf 

 Giacomo Bonanno,   Two lectures on the epistemic foundations of game theory.


These are the slides of  two lectures on the Epistemic Foundations of Game Theory, delivered at the Royal Netherlands Academy of Arts and Sciences (KNAW), February 8, 2007.

                             To download the files in pdf format click here: Lecture 1.pdfLecture 2.pdf 

 Giacomo Bonanno (with Klaus Nehring),   Agreeing to disagree: a survey.

                             To download the paper in pdf format click here: agree.pdf

Some of the material in this paper was published in: Giacomo Bonanno and Klaus Nehring, “How to make sense of the common prior assumption under incomplete information", International Journal of Game Theory, 28 (3), August 1999, pp. 409-434 (To download the paper in pdf format click here: common.pdf)