My primary research interest is in microeconomic theory, with an emphasis on game theory and decision theory. I have worked on existence of equilibrium in games with payoffs that lack the usual continuity properties, as well as games with imperfect information with neither an a priori order structure nor convexity assumptions on strategy spaces or payoff functions. That work has resulted in several working papers, including a contribution to the fixed point theory of decomposable sets in non-linear analysis. More recently, I have been studying learning and belief formation in an environment in which little information is available to the economic agent and surprises are frequent. I have also been continuously involved in the organization of conferences, workshops, seminars, and minicourses for the Australian National University, many of them multidisciplinary.
On the existence of equilibrium in Bayesian games without complementarities [pdf]
(with Rabee Tourky)
This paper presents new results on the existence of pure-strategy Bayesian equilibria in specified functional forms. These results broaden the scope of methods developed by Reny (2011) well beyond monotone pure strategies. Applications include natural models of first-price and all-pay auctions not covered by previous existence results. To illustrate the scope of our results, we provide an analysis of three auctions: (i) a first-price auction of objects that are heterogeneous and imperfect substitutes; (ii) a first-price auction in which bidders’ payoffs have a very general interdependence structure; and (iii) an all-pay auction with non-monotone equilibrium.
Keywords: Bayesian games, monotone strategies, pure-strategy equilibrium, auctions
Learning under unawareness [pdf]
(with Simon Grant and Rabee Tourky)
This paper proposes a model of learning when experimentation is possible, but unawareness and ambiguity matter. In this model, complete lack of information regarding the underlying data generating process is expressed as a (maximal) family of priors. These priors yield posterior inferences that become more precise as more information is available. As information accumulates, the decision maker’s level of awareness as encoded in the state space expands. Newly learned states are initially seen as ambiguous, but as evidence accumulates there is a gradual reduction of ambiguity.
Keywords: learning, ambiguity, unawareness
A fixed point theorem for closed-graphed decomposable-valued correspondences [pdf]
(with Rabee Tourky)
Extending the fixed-point theorem of Cellina–Fryszkowski [1, 7], which is for functions on decomposable sets, to decomposable-set-valued correspondences has been an unresolved challenge since the early attempt of Cellina, Colombo, and Fonda . Motivated by the fixed point problem of Reny  arising in Bayesian games, this paper proves such a theorem.
Keywords: fixed point, decomposable set
- Grant, S., Kline, J., Meneghel, I., Quiggin, J., and Tourky, R. (2016). “A theory of robust experiments for choice under uncertainty.” Journal of Economic Theory, 165, pp. 124-151.
- Grant, S., Meneghel, I., and Tourky, R. (2016). “Savage games.” Theoretical Economics, 1 (2), pp. 641-682.
- Barelli, P. and Meneghel, I. (2013). “A note on the equilibrium existence problem in discontinuous games.” Econometrica, 81 (2), pp. 813-824.