Research
PUBLICATIONS
Rationing rules and stable coalition structures (with Elena Inarra), Theoretical Economics, 13 (2018) 933-950.
This paper introduces a model of coalition formation with claims. It assumes that agents have claims over the outputs that they could produce by forming coalitions. Outputs are insufficient to meet the claims and are rationed by a rule whose proposals of division induce each agent to rank the coalitions in which she can participate. As a result, a hedonic game of coalition formation emerges. Using resource monotonicity and consistency, we characterize the continuous rationing rules that induce hedonic games that admit core stability.
Solidarity to achieve stability (with J. Alcalde-Unzu, E. Inarra and J. Moreno-Ternero), European Journal of Operational Research, 315 (2024) 368-377.
Agents belong to coalitions. Each coalition shares its endowment among its agents according to a sharing rule. The sharing rule induces a coalition formation problem by assuming agents rank coalitions according to the allocation they obtain in the corresponding sharing problem. We characterize the sharing rules that induce non-circular coalition formation problems (and, thus, with a non-empty core) as those satisfying a natural axiom formalizing the principle of solidarity. Thus, solidarity becomes a sufficient condition to achieve stability.
Strategy-proofness in a mixed domain of single-peaked and single-dipped preferences (with Jorge Alcalde-Unzu and Marc Vorsatz), forthcoming at Games and Economic Behavior.
We analyze the problem of locating a public facility in a domain of single-peaked and single-dipped preferences where the type of preference (single-peaked or singledipped) of each agent is known, but there is no information about either the position of her peak or dip or the rest of the preference. In this framework, we characterize all strategy-proof social choice rules and show that they all are also group strategyproof. We find that each of these rules can be decomposed into two steps: in the first step, agents with single-peaked preferences reveal their peaks and then, at most two alternatives are preselected; in the second step, agents with single-dipped preferences reveal their dips to complete the decision between the preselected alternatives. We also study which strategy-proof rules satisfy Pareto efficiency.
WORKING PAPERS
Stable partitions for proportional generalized claims problems (with Bettina Klaus), minor revision requested at Games and Economic Behavior
We consider a set of agents who have claims on an endowment that is not large enough to cover all claims. Agents can form coalitions but a minimal coalition size θ is required to have positive coalitional funding that is proportional to the sum of the claims of its members. We analyze the structure of stable partitions when coalition members use well-behaved rules to allocate coalitional endowments, e.g., the well-known constrained equal awards rule (CEA) or the constrained equal losses rule (CEL). For continuous, (strictly) resource monotonic, and consistent rules, stable partitions with (mostly) θ-size coalitions emerge. For CEA and CEL we provide algorithms to construct such a stable partition formed by θ-size coalitions.
WORK IN PROGRESS
Anonymity and strategy-proofness with single-peaked and single-dipped preferences, job market paper.
We analyze the problem of locating a public facility on a line in a society where agents can have either single-peaked preferences or single-dipped preferences. We consider the domain analyzed in Alcalde-Unzu et al. (2023) where the type of preference of each agent is public information and both the location of her peak/dip and the rest of the preference are unknown. We characterize all strategy-proof and anonymous rules on this domain. We first show the additional conditions that anonymity imposes on the strategy-proof rules characterized by Alcalde-Unzu et al. (2023). We also provide an alternative ``two-step characterization": First, the median between the peaks and a collection of fixed values is computed (Moulin, 1980) and, as a result, either a single alternative or a pair of contiguous alternatives arise. If the outcome of the median is a pair, we apply a "double-quota majority method" in the second step to choose between the two alternatives of the pair Moulin, 1983). Finally, we show the equivalence between the two characterizations.