When several two-sided matching markets merge into one, it is inevitable that some agents will become worse off if the matching mechanism used is stable. I formalize this observation by defining the ...property of integration monotonicity, which requires that every agent becomes better off after any number of matching markets merge. Integration monotonicity is also incompatible with the weaker efficiency property of Pareto optimality.
Nevertheless, I obtain two possibility results. First, stable matching mechanisms never hurt more than one half of the society after the integration of several matching markets occurs. Second, in random matching markets there are positive expected gains from integration for both sides of the market, which I quantify.
Although the integration of two-sided matching markets using stable mechanisms generates expected gains from integration, I show that there are worst case scenarios in which these are negative. The ...losses from integration can be large enough that the average rank of an agent’s spouse decreases by 37.5% of the length of their preference list in any stable matching mechanism.
•The integration of matching markets using stable mechanisms can generate welfare losses.•Average rank of an agent’s spouse can decrease by 37.5% of the length of their preference list.•Losses from integration occur only in worst-case scenarios.•In expectation, integration increases welfare for both sides of the market.•Integration also benefits more agents than those it harms.
We propose the notion of k-integration as a measure of equality of opportunity in social networks. A social network is k-integrated if there is a path of length at most k between any two individuals, ...thus guaranteeing that everybody has the same network opportunities to find a job, a romantic partner, or valuable information. We compute the minimum number of bridges (i.e. edges between nodes belonging to different components) or central nodes (those which are endpoints to a bridge) required to ensure k-integration. The answer depends only linearly on the size of each component for k=2, and does not depend on the size of each component for k≥3. Our findings provide a simple and intuitive way to compare the equality of opportunity of real-life social networks.
•We propose k-integration as a measure of equality of opportunity in social networks.•We compute the minimum number of bridges or central nodes required to ensure k-integration.•The answer does not depend on the size of each component for k larger than 2.•Our findings provide a simple way to compare the equality of opportunity of real-life social networks.
Abstract
Epiphytes are characterized by their ability to survive without a root connection to the ground, but many basic life‐history traits and ecological trade‐offs of this unique aerial growth ...habit remain largely uncharacterized. Mortality causes are still not well understood, but falling from the host tree has been suggested as a leading cause of epiphyte mortality and community dynamics. Little empirical evidence exists for
why
epiphytes do not survive when forced to become terrestrial, and few studies exist that transplant epiphytes between high‐ and low‐forest strata to test trade‐offs between thriving in canopy environments and survival in the forest understorey.
Here, we experimentally test two hypotheses regarding the drivers of epiphyte mortality in a cloud forest of central Panama. We test whether simple contact with terrestrial soil is deleterious to epiphytes, preliminarily testing the epiphyte enemy escape hypothesis, and test the vertical niche differentiation hypothesis, wherein epiphytes are specifically adapted for microsites throughout the vertical forest strata. By monitoring survival, leaf loss and health status of 270 transplanted epiphytes for a year and a half, we pinpoint the extent to which soil contact and height of origin regulate epiphyte performance.
We found that contact with terrestrial soil itself was detrimental to epiphytes in situ, providing some of the first empirical data to explain why falling onto the ground, versus falling into the understorey, is particularly fatal to epiphytes. However, we also found that mortality rates vary substantially among taxonomic groups and among epiphytes that originally came from different height strata.
Synthesis
. Plants that are adapted for the canopy experience a trade‐off with higher mortality when in contact with terrestrial soil. Follow‐up studies should explore the role of terrestrial soil microbes and physiological constraints as potential drivers of decreased grounded epiphyte survival.
Resumen
Las epífitas son caracterizadas por su habilidad de sobrevivir sin una conexión de raíces hacia la tierra, pero la historia de vida y los equilibrios de esta forma de crecer único aéreo no son bien caracterizados. Las causas de mortalidad todavía no son bien entendidas, pero caerse del árbol huésped ha sido introducido como un manejador subestimado de los dinámicos de comunidades de epífitas vasculares. Poca evidencia empírica existe por
porque
no sobreviven las epífitas cuando son forzadas estar terrestres, y existen pocos estudios que trasplantan epífitas entre los estratos forestales verticales para probar los equilibrios de sobrevivir en el dosel o en el sotobosque.
Aquí, probamos dos hipótesis experimentalmente hacia los manejadores de la mortalidad de epífitas en un bosque nuboso en el centro de la República de Panamá. Probamos si el contacto simple con la tierra del suelo del bosque es perjudicial para las epífitas, en una prueba preliminar de la Hipótesis de Escapa de Enemigos de Epífitas. También probamos la Hipótesis de Diferenciación Vertical de Nichos, donde las epífitas son específicamente adaptadas por los micrositios a lo largo de los estratos forestales verticales. Por monitorear la supervivencia, la pérdida de hojas, y el estado de salud de 270 epífitas trasplantadas por un año y medio, señalamos la medida en la que el lugar en los estratos forestales regula el rendimiento de las epífitas.
Encontramos que el contacto con la tierra terrestre sí era perjudicial para las epífitas in situ, que provee algunos de los primeros datos empíricos para explicar por qué caerse en el suelo, en comparación a caerse al sotobosque, es particularmente fatal para las epífitas. Sin embargo, también encontramos que las tasas de mortalidad de epífitas diferenciaron sustantivamente entre los grupos taxonómicos y entre las epífitas que originalmente ocurrieron en estratos forestales verticales diferentes.
Síntesis
. Las plantas que son adaptadas para vivir en el dosel experimentan una compensación con mortalidad más alto cuando estén en contacto con el suelo terrestre. Estudios siguientes deben explorar el papel de los microbios de la tierra y las limitaciones fisiológicas como impulsores potenciales de una disminución de la supervivencia en las epífitas caídas.
I study the problem of allocating objects among agents without using money. Agents can receive several objects and have dichotomous preferences, meaning that they either consider objects to be ...acceptable or not. In this set-up, the egalitarian solution is more appealing than the competitive equilibrium with equal incomes because it is Lorenz dominant, unique in utilities, and group strategy-proof. Both solutions are disjoint.
•I study an assignment problem in which agents consider objects to be acceptable or not.•The egalitarian solution is Lorenz dominant, unique in utilities, and group strategy-proof.•The competitive equilibrium with equal incomes fails these three properties.•Both solutions are disjoint.
In the classical cake-cutting problem, strategy-proofness is a very costly requirement in terms of fairness: for
n
=
2
it implies a dictatorial allocation, whereas for
n
≥
3
it implies that one agent ...receives no cake. We show that a weaker version of this property recently suggested by Troyan and Morril (J Econ Theory 185:104970, 2019) is compatible with the fairness property of proportionality, which guarantees that each agent receives 1/
n
of the cake. Both properties are satisfied by the leftmost-leaves mechanism, an adaptation of the Dubins–Spanier moving knife procedure. Most other classical proportional mechanisms in the literature are obviously manipulable, including the original moving knife mechanism and some other variants of it.
We compare the outcomes of the most prominent strategy-proof and stable algorithm (Deferred Acceptance, DA) and the most prominent strategy-proof and Pareto optimal algorithm (Top Trading Cycles, ...TTC) to the allocation generated by the rank-minimizing mechanism (RM). While one would expect that RM improves upon both DA and TTC in terms of rank efficiency, the size of the improvement is nonetheless surprising. Moreover, while it is not explicitly designed to do so, RM also significantly improves the placement of the worst-off student. Furthermore, RM generates less justified envy than TTC. We corroborate our findings using data on school admissions in Budapest.
This paper studies the welfare effects of school district consolidation. Using incomplete rank-ordered lists (ROLs) submitted for admission to the Hungarian secondary school system, we estimate ...complete ROLs assuming that parents do not use dominated strategies and that the matching outcome is stable. These estimates aid in constructing a counterfactual district-based assignment and discerning the factors driving parents' preferences over schools. We find that district consolidation leads to large welfare gains in Budapest, equivalent to students attending a school five kilometres closer to their residences. These gains offset the additional travel distances incurred in the consolidated assignment. 73% of matched students benefit from district consolidation, while fewer than 3% are assigned to a less preferred school. Students from smaller and less under-demanded districts benefit relatively more, as well as those with high academic ability. Using reported preferences instead of estimated ones also yields large gains from district consolidation.
Fair cake-cutting in practice Kyropoulou, Maria; Ortega, Josué; Segal-Halevi, Erel
Games and economic behavior,
20/May , Letnik:
133
Journal Article
Recenzirano
Odprti dostop
Using two lab experiments, we investigate the real-life performance of envy-free and proportional cake-cutting procedures with respect to fairness and preference manipulation. Although the observed ...subjects' strategic behavior eliminates the fairness guarantees of envy-free procedures, we nonetheless find evidence that suggests that envy-free procedures are fairer than their proportional counterparts.
Our results support the practical use of the celebrated Selfridge-Conway procedure, and more generally, of envy-free cake-cutting mechanisms. We also find that subjects learn their opponents' preferences after repeated interaction and use this knowledge to improve their allocated share of the cake. Learning increases strategic behavior, but also reduces envy.
We study the cake-cutting problem where agents have single-peaked preferences over the cake. We show that a recently proposed mechanism by Wang and Wu (2019) to obtain envy-free allocations can yield ...large welfare losses. Using a simplifying assumption, we characterize all Pareto optimal allocations, which have a simple structure: are peak-preserving and non-wasteful. Finally, we provide simple alternative mechanisms that Pareto dominate that of Wang–Wu and achieve envy-freeness or Pareto optimality.
•We study cake-cutting with single-peaked preferences.•We show that the Wang–Wu (2019) mechanism generates large welfare losses.•We characterize all Pareto optimal allocations.•We provide alternative mechanisms that Pareto dominate Wang–Wu.
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