Sistemas multiagentes muitas vezes apresentam características que os aproximam de sociedades de agentes e, como as humanas, possuem normas e organizações com o objetivo de coordenar as interações entre os seus membros. Coalizão é um tipo de estrutura organizacional temporária, montada com objetivos específicos. A teoria dos jogos estuda formalmente o fenômeno coalizional, se detendo em demonstrações de propriedades e características dessa estrutura. A área de sistemas multiagentes, por outro lado, tem mostrado significativo interesse nas estruturas coalizionais como forma de organizar a cooperação entre os agentes, dedicando-se ao desenvolvimento de algoritmos para formação de coalizões. Esse trabalho apresenta um algoritmo de formação de coalizões para compartilhamento de recursos, denominado heurística ganha-ganha. Definimos um modelo que utiliza a abstração de recursos para representar tanto a posse de habilidades e objetos, quanto para representar os objetivos dos agentes. Um jogo de votação k-ponderado é utilizado para implementar o processo decisório de quais coalizões são válidas e o algoritmo testa iterativamente cada vizinhança de um agente na busca de associações vantajosas. Demonstramos que o algoritmo incrementa monotonicamente o bem-estar da sociedade e converge para uma estrutura coalizional. Também mostramos empiricamente que a heurística é eficiente para compartilhamento de recursos em situações de abundância de recursos, montando coalizões em poucas iterações e com uma quantidade grande de agentes. / Multiagent systems frequently show characteristics that come closer to agent societies and, like the humans ones, have norms and organizations in order to coordinate the interactions of its members. Coalition is a type of temporary organizational structure, assembled with specific goals. Game theory formally studies the coalitional phenomenon focusing in the demonstrations of properties and characteristics of this structure. The area of multiagent systems, on the other hand, has devoted significant interest in coalition structures as a way to organize cooperation between its members, and has been dedicated to the development of algorithms for coalition formation. This dissertation presents an algorithm to coalition formation named win-win heuristic. We define a model which uses the abstraction of resources to represent either, the possession of abilities and objects, or to represent the agents target. A k-weight voting game is used to implement the decision process of what coalitions are worth and an iteratively algorithm tests each agent neighborhood in the pursue of better associations. We demonstrate that the algorithm monotonically increases the society welfare and converges to a coalitional structure. We also show empirically that the heuristic is efficient for resource sharing in situations of availability of resources, building coalitions with few iterations and a large amount of agents.

A área de sistemas multiagentes é um promissor domínio tecnológico para uso em performances musicais interativas. Em trabalhos recentes, essa tecnologia vem sendo utilizada para resolver problemas musicais de escopo específico e alcance limitado, como a detecção de pulsação, a simulação de instrumentos e o acompanhamento musical automático. Neste trabalho, apresentamos uma taxonomia desses sistemas multiagentes musicais e uma arquitetura e implementação de um arcabouço computacional que generaliza os trabalhos anteriores e aborda problemas usuais como a sincronização em tempo real, a comunicação sonora e a mobilidade espacial dos agentes. Através do arcabouço, um usuário pode desenvolver um sistema multiagente musical focado em suas necessidades musicais, enquanto deixa grande parte dos problemas técnicos a cargo do arcabouço. Para validar o arcabouço, implementamos e discutimos dois estudos de caso que exploram diversos aspectos de um sistema multiagente musical, como a comunicação simbólica, a troca de áudio digital, o uso de trajetórias espaciais, a simulação acústica e conceitos de vida artificial, como códigos genéticos e reprodução, demonstrando a usabilidade do arcabouço em uma grande variedade de aplicações musicais. / Multiagent system technology is a promising new venue for interactive musical performance. In recent works, this technology has been tailored to solve specific, limited scope musical problems, such as pulse detection, instrument simulation or automatic accompaniment. In this work, we pre- sent a taxonomy of such musical multiagent systems, and an implementation of a computational framework that subsumes previous works and addresses general-interest low-level problems such as real-time synchronization, sound communication and spatial agent mobility. By using it, a user may develop a musical multiagent system focusing primarily in his/her musical needs, while leaving most of the technical problems to the framework. To validate this framework, we implemented and discussed two cases studies that explored several aspects of musical multiagent systems, such as symbolic and audio communication, spatial trajectories and acoustical simulation, and artificial life concepts, like genetic codes and reproduction, thus indicating the usefulness of this framework in a variety of musical applications.

University of Macau / Faculty of Science and Technology. / Department of Computer and Information Science

Esta tese propõe um modelo de adaptação organizacional em Sistemas Multiagentes (SMA) composto por um modelo de organização e um processo de reorganização. O modelo organizacional, chamado de MOISE+, considera três dimensões da organização de um SMA: a estrutura (grupos, papéis e ligações), o funcionamento (planos globais, metas e missões) e as obrigações e permissões dos agentes. A principal característica do modelo MOISE+ é facilitar a mudança organizacional em uma das dimensões sem comprometer as outras. É possível, por exemplo, alterar a estrutura da organização sem alterar o seu funcionamento e vice-versa. O processo de reorganização permite que os próprios agentes realizem a mudança através de quatro etapas: monitoração da organização corrente, projetos de planos de mudança, seleção dos planos e implementação do plano selecionado. A principal característica deste processo é a existência explícita da organização responsável pela reorganização (descrita na notação do modelo MOISE+) permitindo a abertura do processo. Estando a representação deste processo disponível aos agentes, estes podem participar da reorganização, bastando que compreendam a notação do modelo. Este processo foi implementado e avaliado em dois estudos de caso, empresas virtuais e futebol de robôs, nos quais as etapas de seleção e implementação foram enfatizadas, já que existem poucos trabalhos que abordam estas duas etapas do processo de reorganização. / This thesis proposes a reorganization model for Multiagent Systems (MAS). This reorganization model is composed by both an organizational model and a reorganization process. The organization model, called MOISE+, is based on three dimensions: the organizational structure (composed by roles, groups, links, etc.), the organizational functioning (composed by global plans, missions, goals, etc.), and the agents\' obligations and permissions. The MOISE+ model main feature is the independence among these dimensions. It is therefore possible to change the organizational structure without any change in the functioning. The reorganization process enables the agents themselves to perform the reorganization along four phases: monitoring (when to reorganize), design (ways of building a new organization), selection (how to choose a new organization), and implementation (how to change the current running organization). The reorganization process is explicitly described in MOISE+ notation and the agents have access to it. This property enables any agent to participate in the reorganization when he understands MOISE+ notation. The reorganization process is thus open since many agents can joint it. This process was implemented and evaluated in two domains: virtual enterprises and robot soccer. The experiments have focused mainly on the selection and implementation phases since the research on those phases is not very common in the literature.

Systems with time delays have a broad range of applications not only in control systems but also in many other disciplines such as mathematical biology, financial economics, etc. The time delays cause more complex behaviours of the systems. It requires more sophisticated analysis due to the infinite dimensional structure of the space spaces. In this thesis we investigate stability properties associated with output functions of delay systems. Our primary target is the equivalent Lyapunov characterization of input-tooutput stability (ios). A main approach used in this work is the Lyapuno Krasovskii functional method. The Lyapunov characterization of the so called output-Lagrange stability is technically the backbone of this work, as it induces a Lyapunov description for all the other output stability properties, in particular for ios. In the study, we consider two types of output functions. The first type is defined in between Banach spaces, whereas the second type is defined between Euclidean spaces. The Lyapunov characterization for the first type of output maps provides equivalence between the stability properties and the existence of the Lyapunov-Krasovskii functionals. On the other hand, as a special case of the first type, the second type output renders flexible Lyapunov descriptions that are more efficient in applications. In the special case when the output variables represent the complete collection of the state variables, our Lyapunov work lead to Lyapunov characterizations of iss, complementing the current iss theory with some novel results. We also aim at understanding how output stability are affected by the initial data and the external signals. Since the output variables are in general not a full collection of the state variables, the overshoots and decay properties may be affected in different ways by the initial data of either the state variables or just only the output variables. Accordingly, there are different ways of defining notions on output stability, making them mathematically precisely. After presenting the definitions, we explore the connections of these notions. Understanding the relation among the notions is not only mathematically necessary, it also provides guidelines in system control and design. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

Este trabalho apresenta uma arquitetura para fornecer, de forma automática, o reforço de aprendizagem após a aplicação de uma avaliação objetiva dentro de um ambiente de Educação à Distância. Para o desenvolvimento da arquitetura foram usadas tecnologias das áreas de Ontologia e Agentes. A área de Ontologia contribuiu com a construção de materiais de aprendizagem modelados ontologicamente e a construção de ontologias de domínio das disciplinas de Estruturas de Dados I e Análise e Desenvolvimento de Algoritmos I, ministradas nos cursos de Bacharelado em Ciência da Computação e Bacharelado em Sistemas de Informação oferecidos pelo Departamento de Computação da Faculdade de Ciências da UNESP – campus de Bauru - SP. A área de Agentes traz, ao ambiente, agentes de busca capazes de fazer indicações de reforço do conteúdo. A arquitetura foi implementada usando o ambiente de Educação à Distância VirtualCurso, desenvolvido originalmente pelo Laboratório de Tecnologia de Informação Aplicada (LTIA) da UNESP – campus de Bauru - SP. A implementação recebeu o nome de VCurso+. Realizou-se alguns testes com o sistema para verificar se o reforço obteve o efeito esperado na aprendizagem do aluno. / This work presents an architecture to support automatically the apprentice’s reinforcing on environment of Distance Education. In order to develop this architecture technologies from the areas of Ontology & Agents have been used. The Ontology domain has contributed with the building of apprentice’s materials and the construction of domain ontologies for the disciplines of Data Structures I and Analysis & Development of Algorithms I, taught on bachelor's degree of Computer Science and bachelor's degree in Information Systems courses offered at the Computer Science Department of UNESP campus of Bauru SP. The Agents domain has inspered the creation of search agents capable of making indications of content reinforcing. The proposed architecture was implemented in the VirtualCurso enviroment, developped originally at Laboratory of Technology of Information Applied (LTIA) from UNESP campus of Bauru SP and it was called VCurso +. Some tests have been made with the system to verify whether the reinforcing learning proposed by architecture has had the expected effect on the apprentice’s learning.

Nous vivons aujourd'hui dans un monde de plus en plus complexe et interconnecté où de nombreuses entités, de plus en plus intelligentes, génèrent une multitude d'interactions qui peuvent contribuer à enrichir leurs capacités. Nous nous intéressons à la collaboration qui favorisera la réalisation de tâches complexes par ces machines d'aujourd'hui et de demain en stimulant ces interactions structurées et en intégrant des processus de décisions intelligents. Par ce biais, cela contribuera à améliorer leur fonctionnement et pourra participer à leur perfectionnement (meilleures connaissances de leur environnement, rapidité d'action et de décision, apport de nouvelles compétences). L'objectif principal de la thèse est donc de contribuer à la compréhension de ce qu'est la collaboration, de sa définition à sa mise en œuvre, en mettant en lumière ses concepts sous-jacents. Nous proposons une méthode d'analyse du besoin et des contraintes ainsi qu'un modèle d'architecture d'agent collaboratif (HACCA) permettant d'intégrer toutes les caractéristiques des processus collaboratifs que nous présentons. Nous présentons également une première implémentation dans la plateforme multi-agents GAMA.Dans le cadre de cette étude, nous nous intéressons à deux cas d'application d'entités mobiles : les drones et les véhicules connectés. Ainsi nous contribuons également plus largement aux besoins d'autonomie et de décision des drones, des véhicules connectés et autonomes du futur, dans un contexte temporel contraint où la qualité des interactions est primordiale pour optimiser le processus de réalisation des objectifs. / We live today in an increasingly complex and interconnected world where many entities, increasingly intelligent, generate a multitude of interactions that can contribute to enrich their capabilities.We are interested in collaboration that will enable complex tasks to be performed by these machines of today and tomorrow by stimulating these structured interactions and integrating intelligent decision-making processes. In this way, it will contribute to improve their functioning and will be able to participate in their improvement (better knowledge of their environment, speed of action and decision-making, provision of new skills).The main objective of the thesis is therefore to contribute to the understanding of what collaboration is, from its definition to its implementation, by highlighting its underlying concepts. We propose a method of analysis (needs and constraints) and a collaborative agent architecture model (HACCA) to integrate all the characteristics of the collaborative processes that we present. We are also showing a first implementation in the GAMA multi-agent platform.As part of this study, we are interested in two cases of application of mobile entities: drones and connected vehicles.Thus we also contribute more to the autonomy needs and decision-making process of drones, connected and autonomous vehicles of the future, in a constrained temporal context where the quality of interactions is essential to optimize the process of achieving objectives.

Process control is essential in chemical engineering and has diverse applications in automation, manufacturing, scheduling, etc. In this cross-disciplinary work, we shift the domain focus from the control of machines to the control of multiple intelligent agents. Our goal is to improve the optimization problem-solving process, such as optimal regulation of emerging technologies, in a multi-agent system. Achieving that improvement would have potential value both within and outside the chemical engineering community. This work also illustrates the possibility of applying process systems engineering techniques, especially process control, beyond chemical plants. It is very common to observe crowds of individuals solving similar problems with similar information in a largely independent manner. We argue here that the crowds can become more efficient and robust problem-solvers, by partially following the average opinion. This observation runs counter to the widely accepted claim that the wisdom of crowds deteriorates with social influence. The key difference is that individuals are self-interested and hence will reject feedbacks that do not improve their performance. We propose a multi-agent control-theoretic methodology, soft regulation, to model the collective dynamics and compute the degree of social influence, i.e., the level to which one accepts the population feedback, that optimizes the problem-solving performance. Soft regulation is a modeling language for multi-agent sociotechnical systems. The state-space formulation captures the individual learning process (i.e., open loop dynamics) as well as the influence of the population feedback in a straightforward manner. It can model a diverse set of existing multi-agent dynamics. Through numerical analysis and linear algebra, we attempt to understand the role of feedback in multi-agent collective dynamics, thus achieving multi-agent control in sociotechnical systems. Our analysis through mathematical proofs, simulations, and a human subject experiment suggests that intelligent individuals, solving the same problem (or similar problems), could do much better by adaptively adjusting their decisions towards the population average. We even discover that the crowd of human subjects could self-organize into a near-optimal setting. This discovery suggests a new coordination mechanism for enhancing individual decision-making. Potential applications include mobile health, urban planning, and policymaking.

Desde o início do século XXI, vivenciamos uma explosão na produção de informações de diversos tipos, tais como fotos, áudios, vídeos, entre outros. Dentre essas informações, existem aquelas em que a informação pode ser dividida em partes menores, mas que devem ser relacionadas seguindo uma ordem total. Um exemplo deste tipo de informação é um arquivo de vídeo que foi dividido em dez segmentos identificados com números de 1 a 10. Para reproduzir o vídeo original a partir dos segmentos é necessário que seus identificadores estejam ordenados. A estrutura denominada tabela de hash distribuída (DHT) tem sido amplamente utilizada para armazenar, atualizar e recuperar esse tipo de informação de forma eficiente em diversos cenários, como monitoramento de sensores e vídeo sob demanda. Entretanto, a DHT apresenta problemas de escalabilidade quando um membro da estrutura não consegue atender as requisições recebidas, trazendo como consequência a inacessibilidade da informação. Este trabalho apresenta uma arquitetura em camadas denominada MATe, que trata o problema da escalabilidade em dois níveis: estendendo a DHT com a introdução de agentes baseados na utilidade e organizando a quantidade de requisições solicitadas. A primeira camada trata a escalabilidade ao permitir a criação de novos agentes com o objetivo de distribuir as requisições evitando que um deles tenha a escalabilidade comprometida. A segunda camada é composta por grupos de dispositivos organizados de tal forma que somente alguns deles serão escolhidos para fazer requisições. A arquitetura foi implementada para dois cenários onde os problemas de escalabilidade acontecem: (i) monitoramento de sensores; e (ii) vídeo sob demanda. Para ambos cenários, os resultados experimentais mostraram que MATe melhora a escalabilidade quando comparada com as implementações originais da DHT. / Since the beginning of the 21st century, we have experienced an explosive growth in the generation of information, such as photos, audios, videos, among others. Within this information, there are some in which the information can be divided and related following a total order. For example, a video file can be divided into ten segments identified with numbers from 1 to 10. To play the original video from these segments, their identifiers must be fully ordered. A structure called Distributed Hash Table (DHT) has been widely used to efficiently store, update, and retrieve this kind of information in several application domains, such as video on demand and sensor monitoring. However, DHT encounters scalability issues when one of its members fails to answer the requests, resulting in information loss. This work presents MATe, a layered architecture that addresses the problem of scalability on two levels: extending the DHT with the introduction of utility-based agents and organizing the volume of requests. The first layer manages the scalability by allowing the creation of new agents to distribute the requests when one of them has compromised its scalability. The second layer is composed of groups of devices, organized in such a way that only a few of them will be chosen to perform requests. The architecture was implemented in two application scenarios where scalability problems arise: (i) sensor monitoring; and (ii) video on demand. For both scenarios, the experimental results show that MATe improves scalability when compared to original DHT implementations.

Orientadora: Maria das Graças Bruno Marietto. / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-graduação em Engenharia da Informação.