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1. Distribution Fairness in Multiplayer AI Using Shapley Constraints

   https://doi.org/10.1609/aiide.v19i1.27519  

   Gray, Robert C.; Zhu, Jichen; Ontañón, Santiago (October 2023, Proceedings of the AAAI Conference on Artificial Intelligence and Interactive Digital Entertainment)

   Experience management (EM) agents in multiplayer serious games face unique challenges and responsibilities regarding the fair treatment of players. One such challenge is the Greedy Bandit Problem that arises when using traditional Multi-Armed Bandits (MABs) as EM agents, which results in some players routinely prioritized while others may be ignored. We will show that this problem can be a cause of player non-adherence in a multiplayer serious game played by human users. To mitigate this effect, we propose a new bandit strategy, the Shapley Bandit, which enforces fairness constraints in its treatment of players based on the Shapley Value. We evaluate our approach via simulation with virtual players, finding that the Shapley Bandit can be effective in providing more uniform treatment of players while incurring only a slight cost in overall performance to a typical greedy approach. Our findings highlight the importance of fair treatment among players as a goal of multiplayer EM agents and discuss how addressing this issue may lead to more effective agent operation overall. The study contributes to the understanding of player modeling and EM in serious games and provides a promising approach for balancing fairness and engagement in multiplayer environments. 

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2. Multiplayer Modeling via Multi-Armed Bandits

   Gray, Robert C; Zhu, Jichen; Ontañón, Santiago (January 2021, Proceedings of the 3rd IEEE Conference on Games)

   null (Ed.)

   This paper focuses on player modeling in multiplayer adaptive games. While player modeling has received a significant amount of attention, less is known about how to use player modeling in multiplayer games, especially when an experience management AI must make decisions on how to adapt the experience for the group as a whole. Specifically, we present a multi-armed bandit (MAB) approach for modeling groups of multiple players. Our main contributions are a new MAB frame- work for multiplayer modeling and techniques for addressing the new challenges introduced by the multiplayer context, extending previous work on MAB-based player modeling to account for new group-generated phenomena not present in single-user models. We evaluate our approach via simulation of virtual players in the context of multiplayer adaptive exergames. 

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3. No-Regret Learning Dynamics for Extensive-Form Correlated Equilibrium

   Celli, A.; Marchesi, A.; Farina, G.; Gatti, N. (January 2020, NeurIPS)

   null (Ed.)

   The existence of simple, uncoupled no-regret dynamics that converge to correlated equilibria in normal-form games is a celebrated result in the theory of multi-agent systems. Specifically, it has been known for more than 20 years that when all players seek to minimize their internal regret in a repeated normal-form game, the empirical frequency of play converges to a normal-form correlated equilibrium. Extensive-form (that is, tree-form) games generalize normal-form games by modeling both sequential and simultaneous moves, as well as private information. Because of the sequential nature and presence of partial information in the game, extensive-form correlation has significantly different properties than the normal-form counterpart, many of which are still open research directions. Extensive-form correlated equilibrium (EFCE) has been proposed as the natural extensive-form counterpart to normal-form correlated equilibrium. However, it was currently unknown whether EFCE emerges as the result of uncoupled agent dynamics. In this paper, we give the first uncoupled no-regret dynamics that converge to the set of EFCEs in n-player general-sum extensive-form games with perfect recall. First, we introduce a notion of trigger regret in extensive-form games, which extends that of internal regret in normal-form games. When each player has low trigger regret, the empirical frequency of play is close to an EFCE. Then, we give an efficient no-trigger-regret algorithm. Our algorithm decomposes trigger regret into local subproblems at each decision point for the player, and constructs a global strategy of the player from the local solutions at each decision point. 

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4. No-Regret Learning Dynamics for Extensive-Form Correlated Equilibrium

   Celli, A.; Marchesi, A.; Farina, G.; Gatti, N. (January 2020, NeurIPS Workshop on Cooperative AI)

   null (Ed.)

   The existence of simple, uncoupled no-regret dynamics that converge to correlated equilibria in normal-form games is a celebrated result in the theory of multi-agent systems. Specifically, it has been known for more than 20 years that when all players seek to minimize their internal regret in a repeated normal-form game, the empirical frequency of play converges to a normal-form correlated equilibrium. Extensive-form (that is, tree-form) games generalize normal-form games by modeling both sequential and simultaneous moves, as well as private information. Because of the sequential nature and presence of partial information in the game, extensive-form correlation has significantly different properties than the normal-form counterpart, many of which are still open research directions. Extensive-form correlated equilibrium (EFCE) has been proposed as the natural extensive-form counterpart to normal-form correlated equilibrium. However, it was currently unknown whether EFCE emerges as the result of uncoupled agent dynamics. In this paper, we give the first uncoupled no-regret dynamics that converge to the set of EFCEs in n-player general-sum extensive-form games with perfect recall. First, we introduce a notion of trigger regret in extensive-form games, which extends that of internal regret in normal-form games. When each player has low trigger regret, the empirical frequency of play is close to an EFCE. Then, we give an efficient no-trigger-regret algorithm. Our algorithm decomposes trigger regret into local subproblems at each decision point for the player, and constructs a global strategy of the player from the local solutions at each decision point. 

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5. Toxicity by Game Design: How Players Perceive the Influence of Game Design on Toxicity

   https://doi.org/10.1145/3677110  

   Zhang, Zinan; Moradzadeh, Sam; Woan, Andrew; Kou, Yubo (October 2024, Proceedings of the ACM on Human-Computer Interaction)

   Toxicity in online games refers to behaviors where players disrupt the gaming experience of others, leading to adverse outcomes such as depression and low self-esteem. Although scholars have identified various factors contributing to toxicity, ranging from individual motivations to team dynamics to cultural backgrounds, the role of game design has been less frequently discussed. To bridge this gap, we conducted an interview study to explore players' perceptions of how game design influences toxicity. Our research identified four game design elements that participants perceived as contributing factors to the emergency of toxicity in their experiences: team interdependency, fairness, interaction design, and privacy. These findings help us shed light on how game design unintendedly triggers toxic intentions, exposes players to vulnerability, making them potential victims, and affects player interactions which lead to toxicity. We further propose design implications that can mitigate toxicity in online games. 

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