Matteo Triossi

Reliability and Responsibility: a Theory of Endogenous Commitment

A common assumption in Political Science literature is policy commitment: candidates maintain their electoral promises. We drop such assumption and we show that costless electoral campaign can be an effective way of transmitting information to voters. The result is robust to relevant equilibrium refinements. An unavoidable proportion of ambiguous politicians emerges.

Acyclicity and Singleton Cores in Matching Markets

This paper analyzes the role of acyclicity in singleton cores. We show that the absence of simultaneous cycles is a sufficient condition for the existence of singleton cores. Furthermore, acyclicity in the preferences of either side of the market is a minimal condition that guarantees the existence of singleton cores. If firms or workers preferences are acyclical, unique stable matching is obtained through a procedure that resembles a serial dictatorship. Thus, acyclicity generalizes the notion of common preferences. It follows that if the firms or workers preferences are acyclical, unique stable matching is strongly efficient for the other side of the market. JEL Classification Numbers: C71, C78, D71.

Non-Revelation Mechanisms in Many-to-One Markets

In this study we present a simple mechanism in a many-to-one matching market where multiple costless applications are allowed. The mechanism is based on the principles of eligibility and priority and it implements the set of stable matchings in Subgame Perfect Nash Equilibrium. We extend the analysis to a symmetric mechanism where colleges and students interchange their roles. This mechanism also implements the set of stable matchings.

Games with capacity manipulation: incentives and Nash equilibria

Studying the interactions between preference and capacity manipulation in matching markets, we prove that acyclicity is a necessary and sufficient condition that guarantees the stability of a Nash equilibrium and the strategy-proofness of truthful capacity revelation under the hospital-optimal and intern-optimal stable rules. We then introduce generalized games of manipulation in which hospitals move first and state their capacities, and interns are subsequently assigned to hospitals using a sequential mechanism. In this setting, we first consider stable revelation mechanisms and introduce conditions guaranteeing the stability of the outcome. Next, we prove that every stable non-revelation mechanism leads to unstable allocations, unless restrictions on the preferences of the agents are introduced.

Hiring mechanisms, application costs and stability☆

This note considers a hiring mechanism with multiple applications and application costs, which encompasses the common features of many real-world procedures. Multiple applications impose serious coordination problems to colleges, but application costs restore stability. With zero application costs unstable allocations arise at equilibrium. We provide necessary and sufficient conditions that guarantee the stability of the outcomes.

Non-revelation mechanisms in many-to-one markets

In this study we present a simple mechanism in a many-to-one matching market where multiple costless applications are allowed. The mechanism is based on the principles of eligibility and priority and it implements the set of stable matchings in Subgame Perfect Nash Equilibrium. We extend the analysis to a symmetric mechanism where colleges and students interchange their roles. This mechanism also implements the set of stable matchings.

Take-it-or-leave-it contracts in many-to-many matching markets

We study a class of sequential non-revelation mechanisms where hospitals make simultaneous take-it-or-leave-it offers to doctors that either accept or reject them. We show that the mechanisms in this class are equivalent. They (weakly) implement the set of stable allocations in subgame perfect equilibrium. When all preferences are substitutable, the set of equilibria of the mechanisms in the class forms a lattice. Our results reveal a first-mover advantage absent in the model without contracts. We apply our findings to centralize school admissions problems, and we show obtaining pairwise stable allocations is possible through the immediate acceptance mechanism.

A Spatial Model of Voting with Endogenous Proposals: Theory and Evidence from the Chilean Senate

Proposers strategically formulate legislative bills before voting takes place. However, spatial voting models that estimate legislator’s ideological preferences do not explicitly consider this fact. In our model, proposers determine the ideology and valence of legislative bills to maximize their objective functions. Approaching to the median legislator ideology and increasing costly valence increases the passing probability, but usually decreases the proposer’s payoff. Using quantile utility proposer preferences, the model becomes tractable and estimable. In this way, we deal with the bill sample selection problem to estimate legislator’s preferences and also, the ideology of proposers, the proposed valence change, and the ideological stance of the statu quo in a common scale. Using Chilean Senate 2009 - 2011 roll call data, our results suggests that (1) political party affiliation significantly affects Senators’ ideology, (2) popular, young and male Senators are more extremist, and (3) proposers during Bachelet and Pinera’s terms have similar ideologies. Key words:

(Group) Strategy-Proofness and Stability in Many-to-Many Matching Markets

We study the existence of group strategy-proof stable rules in many to-many matching markets. We show that when firms have acyclical preferences over workers the set of stable matchings is a singleton, and the worker-optimal stable mechanism is a stable and group strategy-proof rule for firms and workers. Furthermore, acyclicity is the minimal condition guaranteeing the existence of stable and strategy-proof mechanisms in many-to-many matching markets.We study strategy-profness in many-to many matching markets. We prove that when firms have acyclical preferences over workers and both firms and workers have responsive preferences, the worker-optimal stable mechanism is group strategy-proof and Pareto optimal. Absent any assumption on workers’ references, an Adjusted Serial Dictatorship among workers is stable, group strategy-proof and Pareto optimal for workers. In both cases, the set of stable matchings is a singleton. We show that acyclicity is the minimal condition guaranteeing the existence of stable and strategy-proof mechanisms in many-to-many matching markets. Economic Literature Classification Numbers: C71, C78, D71, D78. Key words: Keywords: Many-to-many markets, Acyclicity, Stability, Group Strategy-proofness, singleton core.

Group Strategy-Proof Stable Mechanisms in Priority-Based Resource Allocation Under Multi-Unit Demand: A Note

In this note we prove that group strategy-proofness and strategy-proofness are equivalent requirements on stable mechanisms in priority-based resource allocation problems with multi-unit demand. JEL Classiffication Numbers: C71; C78; D71; D78; J44. Key words: Keywords: Matching; Multi-unit demand; Stability; Strategy-proofness, Group Strategy-proofness; Essential homogeneity.We prove that group strategy-proofness and strategy-proofness are equivalent requirements on stable mechanisms in priority-based resource allocation problems with multi-unit demand. The result extends to the model with contracts.