Diversification and limited information in the Kelly game

Financial markets, with their vast range of different investment opportunities, can be seen as a system of many different simultaneous games with diverse and often unknown levels of risk and reward. We introduce generalizations to the classic Kelly investment game [Kelly (1956)] that incorporates these features, and use them to investigate the influence of diversification and limited information on Kelly-optimal portfolios. In particular we present approximate formulas for optimizing diversified portfolios and exact results for optimal investment in unknown games where the only available information is past outcomes.Comment: 11 pages, 4 figure

Political and social issues in French digital games, 1982-1993

Despite numerous publications about the history of digital games in the United States and Japan, there are few studies which aim to explore the past European trends in game design. For example, the French gaming industry remains unknown to the vast majority of game researchers. However, from the mid-1980s to the early 1990s a certain tendency emerged in this industry: political and social issues became overtly discussed within digital games. To examine such a tendency, the author follows the ‘emancipatory’ paradigm in digital game research (to cite Jaakko Suominen), instead of the ‘enthusiast’ Trans-Pacific-oriented ones. The objects of the analysis are several adventure games developed in France between 1982 and 1993 whose popularity during this period made them influential for the development of the French gaming industry. The author indicates three factors that contributed to the rapid growth of adventure games. These are the advancement of the personal computer market, the modest but existing support from French national institutions, and the article published by Guy Delcourt in the August 1984 issue of Tilt gaming magazine, which gave critical insight into previous development practices and suggested drawing inspiration from current events. The author distinguishes five thematic genres: Froggy Software’s avant-garde digital games, postcolonial and feminist games, investigative games, science fiction, and horror. Each of these provided numerous references to political affairs, economic stagnation and postcolonial critique of the past, which were severe issues in France during the 1980s and 1990s. Despite strong genre diversity, French adventure games shared similar pessimistic outlooks on the emerging “liquid modernity” (Zygmunt Bauman), during which France had to cope with more unstable work conditions, globalization, and immigration from the Maghreb countries. Because the French gaming industry in this period concentrated on local gamers and referred to their national culture, the author encourages game historians to turn their attention not only to Trans-Pacific games, but also to those manufactured outside Japan and the United States

Prizes and Incentives in Elimination Tournaments

The role of rewards for maintaining performance incentives in multistage, sequential games of survival is studied. The sequential structure is a statistical design-of-experiments for selecting and ranking contestants. It promotes survival of the fittest and saves sampling costs by early elimination of weaker contenders. Analysis begins with the case where competitors' talents are common knowledge and is extended to cases where talents are unknown. It is shown that extra weight must be placed on top ranking prizes to maintain performance incentives of survivors at all stages of the game. The extra weight at the top induces competitors to aspire to higher goals independent of past achievements. In career games workers have many rungs in the hierarchical ladder to aspire to in the early stages of their careers, and this plays an important role in maintaining their enthusiasm for continuing. But the further one has climbed, the fewer the rungs left to attain. If top prizes are not large enough, those who have succeeded in attaining higher ranks rest on their laurels and slack off in their attempts to climb higher. Elevating the top prizes makes the ladder appear longer for higher ranking contestants, and in the limit makes it appear of unbounded length: no matter how far one has climbed, it looks as if there is always the same length to go. Concentrating prize money on the top ranks eliminates the no-tomorrow aspects of competition in the final stages.

Why They Say No (Casi— No ): Countries that Reject Legalized Casino Gambling

Most world venues have legalized casino gambling. Indeed, the numbers of venues has been growing rapidly. In 1986, seventy-seven nations permitted legal casino gambling; in 1996, 109; while recent reports indicate 132 countries have casinos. Nonetheless, there are several cases of jurisdictions rejecting the legalization of casinos. This article seeks to find common reasons for the rejections, and examines the following ten venues: Bhutan, Brazil, Japan, Liechtenstein, Iceland, India, Ireland, Israel, Mexico, and Norway. The study utilizes a framework from the book The Last Resort: Success and Failure in Campaigns for Casinos, by John Dombrink and William N. Thompson. The authors developed a “Veto Model” for explaining why American states rejected casinos in the decades before 1990. Major veto factors influencing casino campaign outcomes included: (1) the economic conditions and state experiences with gambling, (2) the position of political and business elites, and other gaming interests; (3) campaign sponsorship; and (4) whether the dominant issue in a campaign was economics or crime and social problems. For successful campaigns (e.g. Atlantic City, 1976), all factors had to be supportive of casinos

Joint Channel Selection and Power Control in Infrastructureless Wireless Networks: A Multi-Player Multi-Armed Bandit Framework

This paper deals with the problem of efficient resource allocation in dynamic infrastructureless wireless networks. Assuming a reactive interference-limited scenario, each transmitter is allowed to select one frequency channel (from a common pool) together with a power level at each transmission trial; hence, for all transmitters, not only the fading gain, but also the number of interfering transmissions and their transmit powers are varying over time. Due to the absence of a central controller and time-varying network characteristics, it is highly inefficient for transmitters to acquire global channel and network knowledge. Therefore a reasonable assumption is that transmitters have no knowledge of fading gains, interference, and network topology. Each transmitting node selfishly aims at maximizing its average reward (or minimizing its average cost), which is a function of the action of that specific transmitter as well as those of all other transmitters. This scenario is modeled as a multi-player multi-armed adversarial bandit game, in which multiple players receive an a priori unknown reward with an arbitrarily time-varying distribution by sequentially pulling an arm, selected from a known and finite set of arms. Since players do not know the arm with the highest average reward in advance, they attempt to minimize their so-called regret, determined by the set of players' actions, while attempting to achieve equilibrium in some sense. To this end, we design in this paper two joint power level and channel selection strategies. We prove that the gap between the average reward achieved by our approaches and that based on the best fixed strategy converges to zero asymptotically. Moreover, the empirical joint frequencies of the game converge to the set of correlated equilibria. We further characterize this set for two special cases of our designed game

Individual Differences in EWA Learning with Partial Payoff Information

We extend experience-weighted attraction (EWA) learning to games in which only the set of possible foregone payoffs from unchosen strategies are known, and estimate parameters separately for each player to study heterogeneity. We assume players estimate unknown foregone payoffs from a strategy, by substituting the last payoff actually received from that strategy, by clairvoyantly guessing the actual foregone payoff, or by averaging the set of possible foregone payoffs conditional on the actual outcomes. All three assumptions improve predictive accuracy of EWA. Individual parameter estimates suggest that players cluster into two separate subgroups (which differ from traditional reinforcement and belief learning)

Improved Second-Order Bounds for Prediction with Expert Advice

This work studies external regret in sequential prediction games with both positive and negative payoffs. External regret measures the difference between the payoff obtained by the forecasting strategy and the payoff of the best action. In this setting, we derive new and sharper regret bounds for the well-known exponentially weighted average forecaster and for a new forecaster with a different multiplicative update rule. Our analysis has two main advantages: first, no preliminary knowledge about the payoff sequence is needed, not even its range; second, our bounds are expressed in terms of sums of squared payoffs, replacing larger first-order quantities appearing in previous bounds. In addition, our most refined bounds have the natural and desirable property of being stable under rescalings and general translations of the payoff sequence

Sport Separation, Past Experiences and Pre Event Expectations; Conversations with the Para-Equestrian Dressage Riders.

Introduction: The multi-sport structure of the Paralympic Games is one of the main elements that differentiate the Paralympics from other major sporting competitions for Para-Equestrian Dressage athletes. Para-Equestrian Dressage made its Paralympic debut in Atlanta in 1996 and as such is a relatively new Paralympic event (de Haan & Winfield, 2008). As equestrian sports require unique venues and facilities, they are often situated varying distances away of the athletics stadium which is often seen as the most iconic Paralympic image and a symbol of the heart of the Games. Beijing and London will be polar opposites in terms of the location of the equestrian events relative to other sports. In 2008 the equestrian team were based in Hong Kong approximately 1225 miles away from the Paralympic Stadium in Beijing, in 2012 the distance between the equestrian venue (Greenwich) and the Paralympic stadium (Stratford) is approximately 6 miles. It is unknown whether these different levels of physical separation affect an athlete’s sense of belonging and inclusion and ultimately their personal ‘Paralympic experience’. Aim: The am of this study was to explore if past experiences would influence future expectations of ‘Paralympic experience’ specifically in relation to the physical separation of equestrian sport at Beijing 2008 Paralympic Games. Participants: Five members of the British Para-Equestrian Dressage team were interviewed post selection but prior to going out to Hong Kong. One rider had experienced all previous Paralympic Games starting in Atlanta, one rider had experienced both Sydney and Athens, one rider had only experienced Athens and for two riders Beijing was to be their first Paralympic Games. Both male and female athletes were included, and the age of participants ranged from 21 – 44 years. Methods: Where applicable riders where asked about their previous Paralympic experience and all riders were asked about their expectations of what life would be like for them based in Hong Kong during the 2008 Paralympic Games. All participants voluntarily agreed to participate and the interviews took place at a training centre regularly used by the team. All interviews were recorded and transcribed verbatim and validated by the participants. Transcripts were then exposed to content analysis to indentify key themes (Gubrium & Holstein, 2001). Results: All riders regardless of previous Paralympic experience were focussed on the competition itself, the fact that the competition was taking place in Hong Kong rather than Beijing did not concern them. The three riders who had previous Paralympic experience did however discuss the ‘uniqueness of the Paralympic Games’, whilst one of the riders for whom Beijing was his first Paralympics, felt that the Games ‘would be like any other major Para-Equestrian Dressage Competition’ because they ‘would just be with other Para-Equestrian Dressage riders’. All riders expressed a sense of ‘missing out from the main Paralympic experience’ as a result of being in Hong Kong, they all said they were ‘looking forward to spending some time in Beijing and experiencing the closing ceremony’. Conclusion: Paralympics GB is a team made up of teams. A team’s success is measured by medals, but the Paralympic experience goes beyond competition results. Prior to competition the concept of sport separation did not distract the Para-Equestrian Dressage riders from their medal focus. They appeared to be able to separate ‘competition expectations’ from ‘Paralympic experience’. However, it was felt that the ‘Paralympic experience’ would be different in Hong Kong compared to Beijing with a sense of separation during the competition and an anticipated sense of inclusion when in Beijing for the closing ceremony. Faced with a situation of sport separation, it would appear that the opportunity to join the rest of the Paralympic GB team at some point during the Games is fundamental to the separated teams’ sense of inclusion and overall ‘Paralympic experience’