Weak Players Research Articles

Evolution of cooperation in heterogeneous populations with asymmetric payoff distribution.

The emergence and maintenance of cooperation is a complex and intriguing issue, especially in the context of widespread asymmetries in interactions that arise from individual differences in real-world scenarios. This study investigates how asymmetric payoff distribution affects cooperation in public goods games by considering a population composed of two types of individuals: strong and weak. The asymmetry is reflected in the fact that strong players receive a larger share of the public pool compared to weak players. Our results demonstrate that asymmetric payoff distribution can promote cooperation in well-mixed populations and trigger the co-evolution of cooperation between sub-populations of strong and weak players. In structured populations, however, the effect of asymmetric payoff distribution on cooperation is contingent on the proportion of strong players and the extent of their payoff share, which can either foster or inhibit cooperation. By adjusting the interaction probability between strong and weak players based on their spatial arrangement on lattice networks, we find that moderate interaction probabilities most effectively maintain cooperation. This study provides valuable insights into the dynamics of cooperation under asymmetric conditions, highlighting the complex role of asymmetrical interactions in the evolution of cooperation.

Asymmetric population promotes and jeopardizes cooperation in spatial prisoner’s dilemma game

The evolution of cooperation in asymmetric populations has recently garnered widespread attention. In this study, we propose a new asymmetric model to explore the impact of asymmetric behavior on cooperation evolution. Our model assumes that weak players are always forced to cooperate when interacting with strong players, while strong players always receive the temptation payoff. When encountering peers from the same category, players engage in a prisoner’s dilemma game, differing only in the intensity of the dilemma between population categories. Results suggest that in scenarios where traditional network reciprocity can support cooperation, asymmetric interactions between strong and weak players undermine this reciprocity and jeopardize the maintenance of cooperation. Conversely, in scenarios where traditional network reciprocity fails to support cooperation, asymmetric interactions enable strong players to leverage weak cooperative clusters to establish cooperation. However, as the prevalence of asymmetric interactions increases, it becomes detrimental to cooperation within the weak player subgroups, thus undermining overall cooperation. These findings contribute to a deeper understanding of how asymmetry impacts cooperation.

Complex pathways to cooperation emergent from asymmetry in heterogeneous populations.

Cooperation within asymmetric populations has garnered significant attention in evolutionary games. This paper explores cooperation evolution in populations with weak and strong players, using a game model where players choose between cooperation and defection. Asymmetry stems from different benefits for strong and weak cooperators, with their benefit ratio indicating the degree of asymmetry. Varied rankings of parameters including the asymmetry degree, cooperation costs, and benefits brought by weak players give rise to scenarios including the prisoner's dilemma (PDG) for both player types, the snowdrift game (SDG), and mixed PDG-SDG interactions. Our results indicate that in an infinite well-mixed population, defection remains the dominant strategy when strong players engage in the prisoner's dilemma game. However, if strong players play snowdrift games, global cooperation increases with the proportion of strong players. In this scenario, strong cooperators can prevail over strong defectors when the proportion of strong players is low, but the prevalence of cooperation among strong players decreases as their proportion increases. In contrast, within a square lattice, the optimum global cooperation emerges at intermediate proportions of strong players with moderate degrees of asymmetry. Additionally, weak players protect cooperative clusters from exploitation by strong defectors. This study highlights the complex dynamics of cooperation in asymmetric interactions, contributing to the theory of cooperation in asymmetric games.

Rusya-Afrika İlişkilerinin Yeniden Dirilişi: Kapsamlı Bir Değerlendirme - Siyasi, Ekonomik ve Stratejik Dinamikler

When considering global interests, it is evident that Russia aims to weaken the dominance of the United States in the current international order and establish itself as a key player in a multipolar world order. In this context, Russia prefers to pursue a policy based on opportunistic actions that would help it be recognized as a global power in different geographic areas and maintain this status. This article aims to examine Russia's growing relationship with Africa from 2014 to the present within the framework of these objectives. In line with Siegle's (2019) claim, the article will argue that Russia's opportunistic approach and Africa's declaration of itself as a "stage" rather than just a destination for Russia indicate that Africa is a global player. The study will discuss Russia's activities in Africa and its influence on the continent in various areas of cooperation, including economics, security, diplomacy, and geopolitics. Additionally, it will touch upon Russia's competition with other global powers in Africa. In this context, the article will demonstrate that Russia's relationship with African countries aligns with its goals of becoming a major power and undermining the global leadership role of the United States in a manner consistent with its global interests. Despite its increasing presence on the continent, the article will conclude by emphasizing that Russia remains a weak player compared to other global powers due to its limited economic and military resources. Key words: Russia, Africa, South South cooperation, global politics

Strategic Exploration: Pre-emption and Prioritization

Abstract This paper analyses a model of strategic exploration in which competing players independently explore a set of alternatives. The model features a multiple-player multiple-armed bandit problem and captures a strategic trade-off between pre-emption—covert exploration of alternatives that the opponent will explore in the future—and prioritization—exploration of the most promising alternatives. Our results explain how the strategic trade-off shapes equilibrium behaviours and outcomes, for example, in technology races between superpowers and R&D competitions between firms. We show that players compete on the same set of alternatives, leading to duplicated exploration from start to finish, and they explore alternatives that are a priori less promising before more promising ones are exhausted. The model also predicts that competition induces players to implement unreliable technologies too early, even though they should wait for the technologies to mature. Coordinated exploration is impossible even if the alternatives are equally promising, but it can emerge in equilibrium following a phase of pre-emptive competition if there is a short deadline. With asymmetric capacities of exploration, the weak player conducts extensive instead of intensive exploration—exploring as many alternatives as the strong player does but never fully exploring any.

Porewater and solid phase speciation geochemistry of phosphorus in the Western Bay of Bengal: An assessment of depositional pathways

In this study, we used a combination of porewater phosphate and solid-phase P speciation to examine the present-day benthic biogeochemical cycling and pathways of phosphorus (P) deposition at four sites in the western Bay of Bengal (BoB). We concentrate on two regions, with 2 sediment cores from each region. One is the Palar basin where ancient phosphorites and phosphatic grains were discovered before, and the other in the Cauvery basin, where no phosphories are known to occur. Both of these regions fall in the depths of the oxygen minimum zone (OMZ). Our results suggest that the influx of lithogenic material, or lack of it, largely regulates the sedimentary cycling of P in BoB. Both locations lack active phosphogenesis due to substantial inputs of non-reactive P relative to reactive P from river runoff and its quick burial by the ballasting effect, which appears to prevent P from transforming into an authigenic phase. Despite the oxygen-depleted conditions, low bacterial respiration limits the microbial reduction of iron oxyhydroxide and makes the redox cycling of iron a weak player in the sedimentary cycling of P in the studied cores. The burial efficiency of P is relatively high in the Cauvery basin cores owing to the high sediment accumulation rate and suggests that most of the sedimentary P is undergoing burial with a minimum regeneration. Lack of/Very low recent sedimentation in the Palar basin is possibly due to the reported migration of river course towards the south during the mid-to Late Holocene.

Deliberate Nuclear First Use in an Era of Asymmetry: A Game Theoretical Approach

Most nuclear dyads are characterized by some degree of nuclear and conventional asymmetry. This paper argues that these asymmetries create an environment in which deliberate nuclear first use (DNFU) can be rational. This possibility has been discarded in the formal literature on nuclear escalation because of the common reliance on the assumption of mutually assured destruction (MAD). This paper develops a formal model that traces how and under what circumstances two types of DNFU are rational. First, nuclear imbalances and advancements in counterforce technologies create a damage limitation incentive for a strong actor. Second, conventional asymmetry creates an incentive for the coercive use of nuclear weapons by the weaker player. Moreover, this paper illustrates that these asymmetric conditions are a relevant characteristic in important and very different nuclear dyads: DPRK–US, Pakistan–India, and Russia–US. Thus, the model demonstrates the potential core drivers of DNFU in today’s nuclear landscape.

Single leg drop jump is affected by physical capacities in male soccer players following ACL reconstruction

ABSTRACT Single leg drop jump (SLDJ) assessment is commonly used during the later stages of rehabilitation to identify residual deficits in reactive strength but the effects of physical capacity on kinetic and kinematic variables in male soccer players following ACL reconstruction remain unknown. Isokinetic knee extension strength, kinematics from an inertial measurement unit 3D system and SLDJ performance variables and mechanics derived from a force plate were measured in 64 professional soccer players (24.7 ± 3.4 years) prior to return to sport (RTS). SLDJ between-limb differences was measured (part 1) and players were divided into tertiles based on isokinetic knee extension strength (weak, moderate and strong) and reactive strength index (RSI) (low, medium and high) (part 2). Moderate to large significant differences between the ACL reconstructed and uninjured limb in SLDJ performance (d = 0.92–1.05), kinetic (d = 0.62–0.71) and kinematic variables (d = 0.56) were evident. Stronger athletes jumped higher (p = 0.002; d = 0.85), produced greater concentric (p = 0.001; d = 0.85) and eccentric power (p = 0.002; d = 0.84). Similar findings were present for RSI, but the effects were larger (d = 1.52–3.84). Weaker players, and in particular those who had lower RSI, displayed landing mechanics indicative of a ‘stiff’ knee movement strategy. SLDJ performance, kinetic and kinematic differences were identified between-limbs in soccer players at the end of their rehabilitation following ACL reconstruction. Players with lower knee extension strength and RSI displayed reduced performance and kinetic strategies associated with increased injury risk.

Manipulation of moves in sequential contests

In two-player Tullock contests with endogenous timing of moves, the weak player moves early and the strong player follows. This order of moves is the third-best outcome for a contest organiser as it leads to a contest with lower aggregate effort compared to a contest where the players move in reverse order (first best) or simultaneously (second best). We propose that if the contest organiser—who does not know ex ante which player is the strong and which is the weak one—offers a lower price (effort cost) to the player(s) who choose(s) to exert effort early, she can achieve a greater payoff by affecting the contestants’ sequence of moves. We show that there exists no price that generates the first-best outcome. However, there is a price (or a range of prices) that induces both players to move early and receive it, leading to the second-best outcome. We also discuss the case where both players move early but only one receives the low price, e.g., lobbying or Instagram “giveaway” contests.

Bridging time: negotiating serious leisure in intimate couple relationships

ABSTRACT Engaging in competitive leisure and sporting practices can cause relationship tension and stress. This paper explores negotiations of gendered time and serious leisure participation. Using the card game bridge, as a case study, it discusses the ways elite tournament players combine intimate relationships with a competitive mindsport. By having an intimate partner who also plays bridge, participants are able to manage playing competitively and the desire for a life-partner. Whilst offsetting some of the challenges of combining serious leisure with familial responsibilities, our data shows that intimate bridge partnerships move between fun, fights and failures at the table. Given that elite-level mindsport is dominated by men, women are consistently constructed as the weaker player in couple-dyads, despite this not always being the case. Based on qualitative interviews with elite bridge players, the paper speaks to the tensions of negotiating intimate relationships and serious leisure in a time-pressured and gendered world.

A peculiar phenomenon and its potential explanation in the ATP tennis tour finals for singles

Abstract The ATP finals is the concluding tournament of the tennis season since its initiation over 50 years ago. It features the 8 best players of that year and is often considered to be the most prestigious event in the sport other than the 4 grand slams. Unlike any other professional tennis tournament, it includes a round-robin stage where all players in a group compete against each other, making it a unique testbed for examining performance under forgiving conditions, where losing does not immediately result in elimination. Analysis of the distribution of final group standings in the ATP Finals for singles from 1972 to 2021 reveals a surprising pattern, where one of the possible and seemingly likely outcomes almost never materializes. The present study uses a model-free, optimization approach to account for this distinctive phenomenon by calculating what match winning probabilities between players in a group can lead to the observed distribution. Results show that the only way to explain the empirical findings is through a “paradoxical” balance of power where the best player in a group shows a vulnerability against the weakest player. We discuss the possible mechanisms underlying this result and their implications for match prediction, bettors, and tournament organization.

Small-sided game-related physical performance is not influenced by the sprint and power performance of youth male soccer players

The aim of this study was to analyse the effects of sprint and power performance on physical fitness and small-sided game-related physical performance in youth male soccer players, using a median split analysis to separate faster and slower players, and powerful and weaker ones. Thirty youth male soccer players (age = 16.9 ± 1.4 years; height = 174.1 ± 7.1 cm; body mass = 63.1 ± 7.9 kg; % body fat = 15.5 ± 3.2) completed the following physical tests: 40 m linear sprint test, repeated sprint ability (RSA) test, countermovement jump (CMJ), horizontal jump (HJ) and a half-squat (HS) power test. In addition, players completed a 4 vs. 4 with goalkeepers small-sided game while external loads were recorded. According to their sprint and HS power performance, players were divided into fast and slow, and powerful and weak. Faster players performed better in 5 m sprint (p = 0.004, Effect Size (ES) = −1.158), 10 m sprint (p < 0.001, ES =−1.722), 40 m sprint (p < 0.001, ES = −3.268), RSAbest (p < 0.001, ES = −2.415), RSAtotal (p < 0.001, ES = −2.785), CMJ height (p = 0.032, ES = 0.823) and HJ distance (p < 0.001, ES = 1.589), but no significant differences (p > 0.05) were found in external loads during small-side games (SSG). In addition, no significant differences (p > 0.05) were observed between powerful and weaker players in the fitness tests and SSG-related physical performance. These results highlight the importance of grouping youth soccer players by their sprinting capacity to design specific and individualized training strategies and suggest that SSG-related physical performance is not influenced by their sprint or power performance.

Asymmetric interaction and diverse forms in public goods production in volunteer dilemma game

Theoretical prediction of classical evolutionary games shows that public goods is contributed either by strong players in asymmetric games or by all of the involved players in symmetric games. However, it is inconsistency with experimental observations that weak players could also contribute to public goods in real cooperation systems. To reconciling these conflicts, we here study an evolutionary volunteer's dilemma game by assuming different roles can be interchangeable. In this model, not only the existence of multiple equilibria is possible but also the evolutionary result of the system depends on initial conditions, which can be interpreted as the production modes of public goods under different circumstances. Specifically, we found that the survival of strong individuals with mixed strategies is associated with two different outcomes: one is similar to Selten's model, that is, public goods are produced by strong players if the defectors are weak players and strong defectors are scarce in the initial condition; and the other is that the weak individuals with mixed strategies produce public goods if the defectors are strong individuals, where the strong cooperators are absent in the initial condition. Moreover, the weak individuals with mixed strategies produce public goods while strong individuals mainly display defection if the cooperation of strong players is absent in the initial condition. Our main results may help to explain the emergence of diverse forms of cooperation in asymmetric evolutionary games.

Asymmetric guessing games

This paper theoretically and experimentally investigates the behavior of asymmetric players in guessing games. The asymmetry is created by introducing $$r>1$$ replicas of one of the players. Two-player and restricted N-player cases are examined in detail. Based on the model parameters, the equilibrium is either unique in which all players choose zero or mixed in which the weak player ( $$r=1$$ ) imitates the strong player ( $$r>1$$ ). A series of experiments involving two and three-player repeated guessing games with unique equilibrium is conducted. We find that equilibrium behavior is observed less frequently and overall choices are farther from the equilibrium in two-player asymmetric games in contrast to symmetric games, but this is not the case in three-player games. Convergence towards equilibrium exists in all cases but asymmetry slows down the speed of convergence to the equilibrium in two, but not in three-player games. Furthermore, the strong players have a slight earning advantage over the weak players, and asymmetry increases the discrepancy in choices (defined as the squared distance of choices from the winning number) in both games.

What Can We Learn Even from the Weakest? Learning Sketches for Programmatic Strategies

In this paper we show that behavioral cloning can be used to learn effective sketches of programmatic strategies. We show that even the sketches learned by cloning the behavior of weak players can help the synthesis of programmatic strategies. This is because even weak players can provide helpful information, e.g., that a player must choose an action in their turn of the game. If behavioral cloning is not employed, the synthesizer needs to learn even the most basic information by playing the game, which can be computationally expensive. We demonstrate empirically the advantages of our sketch-learning approach with simulated annealing and UCT synthesizers. We evaluate our synthesizers in the games of Can't Stop and MicroRTS. The sketch-based synthesizers are able to learn stronger programmatic strategies than their original counterparts. Our synthesizers generate strategies of Can't Stop that defeat a traditional programmatic strategy for the game. They also synthesize strategies that defeat the best performing method from the latest MicroRTS competition.

Too big to prevail: The paradox of power in coalition formation

In standard coalition games, players try to form a coalition to secure a prize and a coalition agreement specifies how the prize is to be split among its members. However, in practical situations where coalitions are formed, the actual split of the prize often takes place after the coalition formation stage. This creates the possibility for some players to ask for a renegotiation of the initial split. We predict that, in such situations, a player can suffer from being “too strong”. Our experimental results confirm that, when the actual split of the prize is delayed, a player's strength can turn into a strategic disadvantage: a greater voting power in forming a winning coalition is undermined by the threat of being overly powerful when a split is determined. This result is relevant to many real world situations where “too strong” players find it paradoxically hard to form coalitions with weaker players.

Costly Waiting in Dynamic Contests: Theory and Experiment

We extend the war of attrition by studying a three-period dynamic contest game. In our game, players can fight against their opponents at certain period of the contest and can flee at any time. Waiting is costly. We focus on the role of waiting costs and show that the value of waiting costs is a key factor in determining the type of equilibrium in such dynamic contests. Specifically, as waiting costs increase, contests end earlier, battles are less likely to occur, and the weaker player in a pair is more likely to flee. A lab experiment verifies most key features of our model. However, unlike theoretical predictions, we find that as waiting costs increase, the duration of contests and the frequency of battles fail to drop as significantly as theory predicted. Moreover, we find that in each treatment, individual players exit the contest significantly earlier than predicted.

The transition of insurgent-guerrilla movements to radical terrorist methods of struggle: retrospective features

The realities of modern reality indicate that there are a significant number of unjustified attempts to resolve controversial issues based on the use of force. The article shows the evolutionary processes of the transition of insurgent-guerrilla movements to radical terrorist methods of struggle in the period of 1991-2001 and reveals the reasons for this process. The article analyzes the definition of "international terrorism" in the modern sense, analyzes the characteristic features of international terrorism of the 1990s, the reasons for its spread, new forms of terrorist activity. The following methods were used in the study of the chosen topic: historical-genetic, comparative-historical; problem-chronological, the method of historical modeling. Authors conclude, there is no doubt that all the insurgent-guerilla movements, without exception, pursued their own goals. The most effective way to achieve them at the turn of the century turned out to be precisely terrorist attacks, which, with all the strength of state structures, were not possible to fend off. Thus, terrorism has become a strong weapon in the hands of weak players in the international arena.

Signaling in the “Before” Model of Final Offer Arbitration

Abstract We develop a signaling model of final offer arbitration (FOA) in which the informed party makes the final settlement demand to the uninformed party. In FOA, each party submits a proposal to an arbitrator and if no agreement is reached, the arbitrator must select one of the two submitted proposals. We analyze a “before” model of FOA in which all settlement activity occurs prior to the exchange of proposals. We characterize the pure strategy separating, equilibrium associated with this game. Relative to a model of conventional arbitration (CA), the pure strategy separating equilibrium is associated with a higher dispute rate because weak player types have an enhanced incentive to bluff in this setting. This result continues to hold in semi-pooling equilibria. Thus our model is consistent with a higher dispute rate in FOA compared to CA. We also compare the incentive to engage in costly voluntary disclosure and costly discovery (JEL K4, C7, J52).

Asymmetrical influence promotes cooperation in the spatial social dilemmas

Asymmetrical influence of population is ubiquitous in human and animal societies. Based on this fact, we construct a setup of asymmetric influence of structured population, which is often put with the combination mechanism of tolerance and punishment when the dispute of unfair outcome happens, to investigate the evolution of cooperation. In detail, the structured populations are classified into two types: A-type players (strong players) and B-type players (weak players). A-type players are capable to decide whether or not to lower the fitness of B-type neighbors with punitive action due to the tolerance limits. This action affects the behavior of B-type neighbors in the evolutionary game. Based on our simulations, it is noted that the mechanism of punishment combining with tolerance in an asymmetrical environment can promote the evolution of cooperation. Furthermore, the lower threshold of tolerance with the looser punishment, the higher the level of cooperation; and the higher degree of tolerance with the stricter punishment will maintain the survival of cooperators. It is also worth mentioning that if A-type population is the key minority impacting the majority of B-type, they can favor affecting and further promoting the evolution of cooperation in the evolutionary game.