The Quality of Equilibria for Set Packing Games

We introduce set packing games as an abstraction of situations in which $n$ selfish players select subsets of a finite set of indivisible items, and analyze the quality of several equilibria for this class of games. Assuming that players are able to approximately play equilibrium strategies, we show that the total quality of the resulting equilibrium solutions is only moderately suboptimal. Our results are tight bounds on the price of anarchy for three equilibrium concepts, namely Nash equilibria, subgame perfect equilibria, and an equilibrium concept that we refer to as $k$-collusion Nash equilibrium

The sequential price of anarchy for affine congestion games with few players

This paper determines the sequential price of anarchy for Rosenthal congestion games with affine cost functions and few players. We show that for two players, the sequential price of anarchy equals 1.5, and for three players it equals approximately 2.13. While the case with two players is analyzed analytically, the tight bound for three players is based on the explicit computation of a worst-case instance using linear programming. The basis for both results are combinatorial arguments to show that finite worst-case instances exist

Understanding land-use change conflict: a systematic review of case studies

The growing demand for food, water, and shelter change the way people use land. These changes have affected or even caused conflict in several locations. However, conflicts do not erupt in isolation; they are the result of multiple interacting causes. There is limited structural understanding of these causes. In this study, we systematically coded case studies that report on conflict related to land-use change, including deforestation in commodity frontiers, agricultural development on common land, and urban development. Based on an analysis of 62 cases, we identified population growth, overlapping land rights, ethnic fragmentation, and economic inequality as the most frequently reported root causes, while rises in land prices was the most often reported proximate cause. Reported institutional causes suggest that the problem is not necessarily the complete absence of governance mechanisms, but rather that governance mechanisms are not fully equipped to deal with the complexities of the observed land-use changes

Revealing charge-tunneling processes between a quantum dot and a superconducting island through gate sensing

We report direct detection of charge-tunneling between a quantum dot and a superconducting island through radio-frequency gate sensing. We are able to resolve spin-dependent quasiparticle tunneling as well as two-particle tunneling involving Cooper pairs. The quantum dot can act as an RF-only sensor to characterize the superconductor addition spectrum, enabling us to access subgap states without transport. Our results provide guidance for future dispersive parity measurements of Majorana modes, which can be realized by detecting the parity-dependent tunneling between dots and islands.Comment: 6 pages, 4 figures, supplemental material included as ancillary fil

Analysis of Equilibria for Generalized Market Sharing Games

We analyze the quality of several equilibria for generalized market sharing games. Generalized market sharing games model n selfish players selecting subsets of a finite set of items, where the payoff of an item is divided among all players choosing that item. Market sharing games are a special case of this, where the available subsets are restricted by budget constraints

Mystery shopping and alcohol sales: do supermarkets and liquor stores sell alcohol to underage customers?

Purpose: \ud The Dutch national policy regarding alcohol and youth relies on retailers’ willingness to refuse to sell alcohol to underage customers. This study examined unobtrusively whether supermarkets and liquor stores do indeed comply with the legal age restrictions for alcohol sales. - \ud \ud Methods:\ud A research protocol was developed based on the methodology of mystery shopping. Using the protocol, 150 supermarkets and 75 liquor stores were visited by 15-year-old adolescents who tried to buy soft alcoholic beverages (legal age, 16 years), and 75 liquor stores were visited by 17-year-old adolescents who tried to buy strong alcoholic beverages (legal age, 18). - \ud \ud Results:\ud Of all 300 buying attempts, 86% were successful. In supermarkets, 88% of all attempts succeeded. In liquor stores, a difference was found between the purchase of strong alcohol by 17-year-olds (89%) and the purchase of soft alcoholic beverages by 15-year-olds (77%). In only 71 of all visits, mystery shoppers were asked for an ID. In 39% of these cases, they were still able to buy alcohol. Female adolescents were more successful in buying alcohol than male adolescents. - \ud \ud Conclusions:\ud The results show that supermarkets and liquor stores generally fail to see the need for extra care when young customers try to buy alcohol. Legal age restrictions without enforcement and facilitation clearly do not suffice to protect adolescents from early exposure to alcohol