Uncovered Set Choice Rule

I study necessary and sufficient conditions for a choice function to be rationalised in the following sense: there exists a complete asymmetric relation T (a tournament ) such that for each feasible (finite) choice situation, the choice coincides with the uncovered set of T . This notion of rationality explains not only cyclical and context dependent choices observed in practice, but also provides testable restrictions on observable choice behavior.Rationalizability, Uncovered set, Intransitive choice

Reason-Based Choice Correspondences

A reason-based choice correspondence rationalizes choice behaviour in terms of a two-stage choice procedure. Given a feasible set S , the individual eliminates from it all of the dominated alternatives according to her fixed (not necessarily complete) strict preference relation, in the first step. In the second step, first she constructs for each maximal alternative identified in the first step its lower contour set (i.e., the set of alternatives which are dominated by it in S ), and then she eliminates from the maximal set all of those alternatives so that the following justification holds: there exists another maximal alternative whose lower contour set strictly contains that of another maximal alternative. This procedural model captures the basic idea behind the experimental finding known as "attraction effect". We study the rationalizability of reason-based choice correspondences axiomatically. We relate our choice-consistency conditions to standard consistency proprieties. Our characterization result offers testable restrictions on this `choice anomaly' for large (but finite) set of alternatives.Reason-based choice, Revealed preferences

Two-agent Nash implementation with partially-honest agents: Almost Full Characterizations

In a two-agent society with partially-honest agents, we extend Dutta and Sen (2009)'s results of Nash implementation to the domain of weak orders. We identify the class of Nash implementable social choice correspondences with a "gap" between necessary and sufficient conditions, both when exactly one agent is partially-honest and when both agents are partially-honest. We also show that, on the domain of linear orders, the "gap" between our conditions gets closed and they become equivalent to those devised by Dutta and Sen. New implementing mechanisms are devised. In line with earlier works, the classic condition of monotonicity is no longer required, whereas a weak version of the standard punishment condition is required even when both agents are known to be partially-honest. We derive simpler sufficient conditions that are satisfied in a wide range of applications.Two-agent Nash implementation, intrinsic preferences for honesty, permissive results

Partially-honest Nash implementation: Characterization results

This paper studies implementation problems in the wake of a recent new trend of implementation theory which incorporates a non-consequentialist flavor of the evidence from experimental and behavioral economics into the issues. Specifically, following the seminal works by Matsushima (2008) and Dutta and Sen (2009), the paper considers implementation problems with partially honest agents, which presume that there exists at least one individual in the society who concerns herself with not only outcomes but also honest behavior at least in a limited manner. Given this setting, the paper provides a general characterization of Nash implementation with partially-honest individuals. It also provides the necessary and sufficient condition for Nash implementation with partially-honest individuals by mechanisms with some types of strategy-space reductions. As a consequence, it shows that, in contrast to the case of the standard framework, the equivalence between Nash implementation and Nash implementation with strategy space reduction no longer holds.

Natural implementation with partially honest agents in economic environments

In this paper, we introduce the weak and the strong notions of partially honest agents (Dutta and Sen, 2012), and then study implementation by natural price-quantity mechanisms (Saijo et al., 1996, 1999) in pure exchange economies with three or more agents in which pure-consequentialistically rational agents and partially honest agents coexist. Firstly, assuming that there exists at least one partially honest agent in either the weak notion or the strong notion, the class of efficient social choice correspondences which are Nash-implementable by such mechanisms is characterized. Secondly, the (unconstrained) Walrasian correspondence is shown to be implementable by such a mechanism when there is at least one partially honest agent of the strong type, which may provide a behavioral foundation for decentralized implementation of the Walrasian equilibrium. Finally, in this set-up, the effects of honesty on the implementation of more equitable Pareto optimal allocations can be viewed as negligible.

Fair social decision under uncertainty and belief disagreements

This paper aims to address two issues related to simultaneous aggregation of utilities and beliefs. The first one is related to how to integrate both inequality and uncertainty considerations into social decision making. The second one is related to how social decision should take disagreements in beliefs into account. To accomplish this, whereas individuals are assumed to abide by Savage model’s of subjective expected utility, society is assumed to prescribe, either to each individual when the ex ante individual well-being is favored or to itself when the ex post individual well-being is favored, acting in accordance with the maximin expected utility theory of Gilboa and Schmeidler (J Math Econ 18:141–153, 1989). Furthermore, it adapts an ex ante Pareto-type condition proposed by Gayer et al. (J Legal Stud 43:151–171, 2014), which says that a prospect Pareto dominates another one if the former gives a higher expected utility than the latter one, for each individual, for all individuals’ beliefs. In the context where the ex ante individual welfare is favored, our ex ante Pareto-type condition is shown to be equivalent to social utility taking the form of a MaxMinMin social welfare function, as well as to the individual set of priors being contained within the range of individual beliefs. However, when the ex post individual welfare is favored, the same Pareto-type condition is shown to be equivalent to social utility taking the form of a MaxMinMin social welfare function, as well as to the social set of priors containing only weighted averages of individual beliefs

Natural Implementation with Partially Honest Agents

The paper proposes necessary and suffi cient conditions for the natural implementation of (efficient) social choice correspondences (SCCs) in pure finite exchange economies when some of the agents are partially honest. A partially honest agent is an agent who strictly prefers to tell the truth when lying has no better material consequences for her. Firstly, it is shown that if there is even one partially honest agent in the economy (and the planner does not know her identity), then any SCC is Nash implementable by a natural price-allocation mechanism. Secondly, and in sharp contrast with the results of conventional models of natural implementation, it is shown that the equivalence relationship between natural price-allocation mechanisms and natural price-quantity2 mechanisms no longer holds. Finally, and even more strikingly, the paper reports that the class of implementable SCCs by natural price-quantity mechanisms is significantly enlarged.Natural implementation, Nash equilibrium, exchange economies, intrinsic preferences for honesty

Alternative Characterizations of the Proportional Solution for Nonconvex Bargaining Problems with Claims

We provide three alternative characterizations of the proportional solution defined on compact and comprehensive bargaining problems with claims that are not necessarily convex. One characterization result is obtained by using, together with other standard axioms, two solidarity axioms. Another characterization theorem shows that the single-valuedness axiom is dispensable even within the class of nonconvex problems if the standard symmetry axiom is imposed.Bargaining problems, claims point, proportional solution, nonconvexity, solidarity axioms

Natural implementation with partially hones agents

The paper proposes necessary and sufficient conditions for the natural implementation of(efficient) social choice correspondences (SCCs) in pure finite exchange economies when some ofthe agents are partially honest. A partially honest agent is an agent who strictly prefers to tellthe truth when lying has no better material consequences for her. Firstly, it is shown that ifthere is even one partially honest agent in the economy (and the planner does not know heridentity), then any SCC is Nash implementable by a natural price-allocation mechanism. Secondly,and in sharp contrast with the results of conventional models of natural implementation, it isshown that the equivalence relationship between natural price-allocation mechanisms and naturalprice-quantity² mechanisms no longer holds. Finally, and even more strikingly, the paper reportsthat the class of implementable SCCs by natural price-quantity mechanisms is significantly enlarged.mathematical economics;