Role Based Hedonic Games

In the hedonic coalition formation game model Roles Based Hedonic Games (RBHG), agents view teams as compositions of available roles. An agent\u27s utility for a partition is based upon which role she fulfills within the coalition and which additional roles are being fulfilled within the coalition. I consider optimization and stability problems for settings with variable power on the part of the central authority and on the part of the agents. I prove several of these problems to be NP-complete or coNP-complete. I introduce heuristic methods for approximating solutions for a variety of these hard problems. I validate heuristics on real-world data scraped from League of Legends games

Novel Hedonic Games and Stability Notions

We present here work on matching problems, namely hedonic games, also known as coalition formation games. We introduce two classes of hedonic games, Super Altruistic Hedonic Games (SAHGs) and Anchored Team Formation Games (ATFGs), and investigate the computational complexity of finding optimal partitions of agents into coalitions, or finding - or determining the existence of - stable coalition structures. We introduce a new stability notion for hedonic games and examine its relation to core and Nash stability for several classes of hedonic games

MODELING, LEARNING AND REASONING ABOUT PREFERENCE TREES OVER COMBINATORIAL DOMAINS

In my Ph.D. dissertation, I have studied problems arising in various aspects of preferences: preference modeling, preference learning, and preference reasoning, when preferences concern outcomes ranging over combinatorial domains. Preferences is a major research component in artificial intelligence (AI) and decision theory, and is closely related to the social choice theory considered by economists and political scientists. In my dissertation, I have exploited emerging connections between preferences in AI and social choice theory. Most of my research is on qualitative preference representations that extend and combine existing formalisms such as conditional preference nets, lexicographic preference trees, answer-set optimization programs, possibilistic logic, and conditional preference networks; on learning problems that aim at discovering qualitative preference models and predictive preference information from practical data; and on preference reasoning problems centered around qualitative preference optimization and aggregation methods. Applications of my research include recommender systems, decision support tools, multi-agent systems, and Internet trading and marketing platforms

Análise da estabilidade de jogos hedônicos

Orientadores: Rafael Crivellari Saliba Schouery, Eduardo Candido XavierDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de ComputaçãoResumo: Jogos hedônicos são jogos de formação de coalizão nos quais os agentes apenas se importam ou são influenciados pelos agentes na mesma coalizão que eles estão. Os agentes podem formar qualquer coalizão que eles queiram e cada agente tem um perfil de preferência, uma ordem fraca sobre o conjunto de coalizões que o contém indicando sua preferência. Um jogo hedônico é definido por um conjunto de agentes e seus perfis de preferência. Classicamente, o resultado de tais jogos é uma partição do conjunto de agentes. Nesta dissertação, nós revisamos alguns resultados da literatura a respeito da existência de resultados Nash estáveis, do preço da anarquia e estabilidade, da existência de partições no núcleo e da complexidade de computar um resultado que está no núcleo. Estudamos o modelo de jogos hedônicos que permite a formação de coalizões com sobreposição. Esta extensão permite a representação de vários cenários como interações sociais, grupos de trabalhos e formação de redes. Nós apresentamos um modelo para jogos fracionários com sobreposição de coalizões e mostramos que o núcleo não é vazio para jogos representados por circuitos, caminhos e grafos bipartidos com emparelhamento perfeito. Nós também apresentamos um modelo para jogos hedônicos aditivamente separáveis com sobreposição de coalizões. Mais ainda, mostramos que, para jogos hedônicos aditivamente separáveis simétricos com sobreposição de coalizões, o bem-estar social de qualquer estrutura de coalizão é no máximo o bem-estar social ótimo da versão do jogo sem sobreposição de coalizõesAbstract: Hedonic games are coalition formation games where the agents only care or are influenced by agents in the same coalition as they are. Agents may form any coalition they want, and every agent has a preference profile, a weak ordering on the set of coalitions that contains it. A hedonic game is defined by a set of agents and their profile preferences. Classically, the outcome of such games is a partition of the agent set. We review some literature results regarding the existence of Nash stable outcomes, the price of anarchy and stability, the existence of core stable partitions, and the complexity to compute a Core stable outcome. We extend the hedonic games model by allowing the formation of overlapping coalitions. This extension permits the representation of many scenarios by hedonic games, such as social interactions, working groups, and network formation. We give a model for fractional hedonic games with overlapping coalitions and we show that the core is not empty for games represented by cycles, paths, and bipartite graphs with perfect matching. We also give a model for additively separable hedonic games with overlapping coalitions. Moreover, we show that for symmetric additively separable hedonic games with overlapping coalitions, the social welfare of any coalition structure is at most the optimal social welfare of the game version without overlapping coalitionsMestradoCiência da ComputaçãoMestre em Ciência da ComputaçãoCAPE