Shurojit Chatterji

Random Dictatorship Domains

A domain of preference orderings is a random dictatorship domain if every strategy-proof random social choice function satisfying unanimity defined on the domain is a random dictatorship. Gibbard (1977) showed that the universal domain is a random dictatorship domain. We ask whether an arbitrary dictatorial domain is a random dictatorship domain and show that the answer is negative by constructing dictatorial domains that admit anonymous, unanimous, strategy-proof random social choice functions which are not random dictatorships. Our result applies to the constrained voting model. Lastly, we show that substantial strengthenings of linked domains (a class of dictatorial domains introduced in Aswal et al., 2003) are needed to restore random dictatorship and such strengthenings are “almost necessary”.

On Domains That Admit Well-behaved Strategy-proof Social Choice Functions

In this paper, we investigate domains that admit “well-behaved” strategy-proof social choice functions. We show that if the number of voters is even, then every domain that satisfies a richness condition and admits an anonymous, tops-only, unanimous and strategy-proof social choice function, must be semi-single-peaked. Conversely every semi-single-peaked domain admits an anonymous, tops-only, unanimous and strategy-proof social choice function. Semi-single-peaked domains are generalizations of single-peaked domains on a tree introduced by Demange (1982) [13].

Local coordination and market equilibria

We reformulate the local stability analysis of market equilibria in a competitive market as a local coordination problem in a market game, where the map associating market prices to best-responses of all traders is common knowledge and well-defined both in and out of equilibrium. Initial expectations over market variables differ from their equilibrium values and are not common knowledge. This results in a coordination problem as traders use the structure of the market game to converge back to equilibrium. We analyse a simultaneous move and a sequential move version of the market game and explore the link with local rationalizability.

A characterization of single-peaked preferences via random social choice functions

The paper proves the following result: every path-connected domain of preferences that admits a strategy-proof, unanimous, tops-only random social choice function satisfying a compromise property, is single-peaked. Conversely, every single-peaked domain admits a random social choice function satisfying these properties. Single-peakedness is dened with respect to arbitrary trees. The paper provides a justication of the salience of single-peaked preferences and evidence in favour of the Gul conjecture (Barber a (2010)).

Unilateral Measures and Emissions Mitigation

Do unilateral measures to cut emissions provide an adequate foundation for global climate change negotiations from a post-Copenhagen perspective? We document the extent and variety for unilateral measures. In a formal model, we examine the conditions under which global learning, by building on the positive spillovers generated by unilateral measures, delivers cumulative emissions reduction over time. Using our results, we analyze the key features of a global policy regime builds on unilateral measures to accelerate convergence to a low carbon world.

ON STRATEGY-PROOFNESS AND THE SALIENCE OF SINGLE-PEAKEDNESS: SEMILATTICE SINGLE-PEAKEDNESS

We consider strategy-proof social choice functions operating on a rich domain of preference profiles. We show that if the social choice function satisfies in addition tops-onlyness, anonymity and unanimity then the preferences in the domain have to satisfy a variant of single-peakedness (referred to as semilattice single-peakedness). We do so by deriving from the social choice function an endogenous partial order (a semilattice) from which the notion of a semilattice single-peaked preference can be defined. We also provide a converse of this main finding. Finally, we show how well-known restricted domains under which nontrivial strategy-proof social choice functions are admissible are semilattice single-peaked domains.

Unilateral Emissions Mitigation, Spillovers, and Global Learning

Whats the role of unilateral measures in global climate change mitigation in a post-Durban, post 2012 global policy regime? We argue that under conditions of preference heterogeneity, unilateral emissions mitigation at a subnational level may exist even when a nation is unwilling to commit to emission cuts. We establish that under certain assumptions, in a global strongly connected network of countries, learning the costs of switching to a low emissions activity can result in a universal adoption of such activities. We analyze the features of a policy proposal that could accelerate convergence to a low carbon world in the presence of global learning.