Experimental realization of a quantum game on a one-way quantum computer

We report the first demonstration of a quantum game on an all-optical one-way quantum computer. Following a recent theoretical proposal we implement a quantum version of Prisoner's Dilemma, where the quantum circuit is realized by a 4-qubit box-cluster configuration and the player's local strategies by measurements performed on the physical qubits of the cluster. This demonstration underlines the strength and versatility of the one-way model and we expect that this will trigger further interest in designing quantum protocols and algorithms to be tested in state-of-the-art cluster resources.Comment: 13 pages, 4 figure

Point-of-Purchase Alcohol Ads in One Low-Income Community in Central California: Occurrence and Women’s Perceptions

This study explores the occurrence of point-of-purchase (POP) alcohol ads in one low-income community Central California, identifies their target audience and themes, and obtains their perspective on how the ads influence women’s alcohol consumption. Methods included observation of POP alcohol ads in local supermarket and convenience stores that sell alcohol products, content analysis of a selection of these POP alcohol ads, and focus group discussions with young women who are mostly in their twenties from both Latina and non-Latina backgrounds. A total of 2,021 POP alcohol ads were observed in 164 retail establishments that sell alcohol. Of these ads, we took photos of 64 different ads for content analysis. Our content analysis indicated that most POP alcohol poster ads appealed both to men and women, with themes mainly related to sex and sports. Focus group interviews indicated that sex and sports-themed alcohol ads, coupled with the presence of peers and family members that drink alcohol, are influential in women’s decisions to drink. The influence of alcohol ads on norms regarding alcohol consumption warrant stronger anti-alcohol policies, such as the banning alcohol ads in places frequented by minors, and the implementation of anti-alcohol marketing campaigns with a health consequences focus

Quantum Games

In these lecture notes we investigate the implications of the identification of strategies with quantum operations in game theory beyond the results presented in [J. Eisert, M. Wilkens, and M. Lewenstein, Phys. Rev. Lett. 83, 3077 (1999)]. After introducing a general framework, we study quantum games with a classical analogue in order to flesh out the peculiarities of game theoretical settings in the quantum domain. Special emphasis is given to a detailed investigation of different sets of quantum strategies.Comment: 13 pages (LaTeX), 3 figure

Computing Stable Coalitions: Approximation Algorithms for Reward Sharing

Consider a setting where selfish agents are to be assigned to coalitions or projects from a fixed set P. Each project k is characterized by a valuation function; v_k(S) is the value generated by a set S of agents working on project k. We study the following classic problem in this setting: "how should the agents divide the value that they collectively create?". One traditional approach in cooperative game theory is to study core stability with the implicit assumption that there are infinite copies of one project, and agents can partition themselves into any number of coalitions. In contrast, we consider a model with a finite number of non-identical projects; this makes computing both high-welfare solutions and core payments highly non-trivial. The main contribution of this paper is a black-box mechanism that reduces the problem of computing a near-optimal core stable solution to the purely algorithmic problem of welfare maximization; we apply this to compute an approximately core stable solution that extracts one-fourth of the optimal social welfare for the class of subadditive valuations. We also show much stronger results for several popular sub-classes: anonymous, fractionally subadditive, and submodular valuations, as well as provide new approximation algorithms for welfare maximization with anonymous functions. Finally, we establish a connection between our setting and the well-studied simultaneous auctions with item bidding; we adapt our results to compute approximate pure Nash equilibria for these auctions.Comment: Under Revie

A Comparison of the Notions of Optimality in Soft Constraints and Graphical Games

The notion of optimality naturally arises in many areas of applied mathematics and computer science concerned with decision making. Here we consider this notion in the context of two formalisms used for different purposes and in different research areas: graphical games and soft constraints. We relate the notion of optimality used in the area of soft constraint satisfaction problems (SCSPs) to that used in graphical games, showing that for a large class of SCSPs that includes weighted constraints every optimal solution corresponds to a Nash equilibrium that is also a Pareto efficient joint strategy

On Budget-Feasible Mechanism Design for Symmetric Submodular Objectives

We study a class of procurement auctions with a budget constraint, where an auctioneer is interested in buying resources or services from a set of agents. Ideally, the auctioneer would like to select a subset of the resources so as to maximize his valuation function, without exceeding a given budget. As the resources are owned by strategic agents however, our overall goal is to design mechanisms that are truthful, budget-feasible, and obtain a good approximation to the optimal value. Budget-feasibility creates additional challenges, making several approaches inapplicable in this setting. Previous results on budget-feasible mechanisms have considered mostly monotone valuation functions. In this work, we mainly focus on symmetric submodular valuations, a prominent class of non-monotone submodular functions that includes cut functions. We begin first with a purely algorithmic result, obtaining a $\frac{2e}{e-1}$-approximation for maximizing symmetric submodular functions under a budget constraint. We view this as a standalone result of independent interest, as it is the best known factor achieved by a deterministic algorithm. We then proceed to propose truthful, budget feasible mechanisms (both deterministic and randomized), paying particular attention on the Budgeted Max Cut problem. Our results significantly improve the known approximation ratios for these objectives, while establishing polynomial running time for cases where only exponential mechanisms were known. At the heart of our approach lies an appropriate combination of local search algorithms with results for monotone submodular valuations, applied to the derived local optima.Comment: A conference version appears in WINE 201

A designer's approach: How can autistic adults with learning disabilities be involved in the design process?

Autistic adults with limited speech and additional learning disabilities who are often excluded from design research are at the heart of this project. These are people whose perceptions, experiences and interactions with their surroundings are unique, but also are people who may not be able to communicate verbally their differences to the remaining 99% of the population. This, in combination with their distinctive cognitive profile, has resulted in a lack of studies involving people living with autism, and consequently their life experiences may neither be heard nor understood and remain largely unexplored. By reflecting upon the ongoing design collaboration between The Helen Hamlyn Centre for Design and the autism charity The Kingwood Trust, this paper reflects on the approach and methods used in three design studies. Particular attention is paid towards the careful selection, adaptation and development of collaborative design methods for autistic adults and their support staff to be involved. By working beyond the boundaries of a neurotypical culture, the project aims to support the greater goal of improving the everyday experiences of people living with autism by breaking down the barriers to participation