Logic-based formalizations of dynamical systems are central to the field of knowledge representation and reasoning. These formalizations can be used to model agents that act, reason,and perceive in a changing and incompletely known environment. A key aspect of reasoning about agents and their behaviors is the notion of joint ability. A team of agents is jointly able to achieve a goal if despite any incomplete knowledge or even false beliefs about the world or each other, they still know enough to be able to get to a goal state, should they choose to do so. A particularly challenging issue associated with joint ability is how team members can coordinate their actions. Existing approaches often require the agents to communicate to agree on a joint plan. In this thesis, we propose an account of joint ability that supports coordination among agents without requiring communication, and that allows for agents to have incomplete (or even false) beliefs about the world or the beliefs of other agents. We use ideas from game theory to address coordination among agents. We introduce the notion of a strategy for each agent which is basically a plan that the agent knows how to follow. Each agent compares her strategies and iteratively discards those that she believes are not good considering the strategies that the other agents have kept. Our account is developed in the situation calculus, a logical language suitable for representing and reasoning about action and change that is extended to support reasoning about multiple agents. Through several examples involving public, private, and sensing actions, we demonstrate how symbolic proof techniques allow us to reason about team ability despite incomplete specifications about the beliefs of agents.

Neste trabalho é proposto um modelo para estimar a geração e a distribuição de viagens intraurbanas baseado em agentes, denominado Modelo GDA. Neste modelo foram aplicadas simulações em Sistemas Multiagentes (SMA), nas quais foram usadas, como dados de entrada, informações relativas ao morador e ao uso do solo. Na estimativa da geração de viagens, a simulação SMA foi usada para estimar uma população sintética baseada nas informações sociodemográficas dos moradores e para obter um plano de atividades associado a cada morador. Na estimativa da distribuição de viagens, a simulação SMA foi usada para obter uma matriz Origem-Destino (OD) com base no plano de atividades dos moradores e nos atributos do uso do solo. Para definir os critérios da distribuição de viagens, foram testadas teorias alternativas à força gravitacional, como a teoria das redes livres de escala e o conceito de path dependence. Foi feita uma aplicação do Modelo GDA na cidade de São Carlos (SP), cujos resultados estimados foram comparados aos resultados observados, provenientes da pesquisa Origem-Destino (OD), e aos resultados estimados obtidos pela aplicação de modelos gravitacionais nesta cidade. Os resultados mostraram que os resultados estimados obtidos pelo Modelo GDA são tão acurados quanto aos do modelo gravitacional. Conclui-se que o Modelo GDA, comparativamente ao modelo gravitacional, possui vantagens quanto à sua aplicabilidade, pois em vez de serem utilizados pelo modelo dados provenientes de pesquisas de tráfego, geralmente onerosos e de difícil aquisição; são empregados dados acerca do morador e do uso do solo, de fácil coleta e atualização periódica. / In this work, an agent-based model in order to estimate trip generation and trip distribution in an intra-urban context (GDA model) is proposed. Simulations using Multiagent Systems (MAS), with input data concerning dwellers and land use were applied in this model. To estimate the trip generation, the MAS simulation was used to elaborate a synthetic population based on sociodemographic information of the dwellers and to obtain an activity plan of each dweller. To estimate the trip distribution, the MAS simulation was used to obtain an Origin-Destiny (OD) matrix based on the dwellers activity plans and the land use characteristics. To define the trip distribution rules, alternative theories to gravitational force like free scale networks and path dependence theories were tested. The GDA model was applied in the urban area of São Carlos (Brazil), whose estimates was compared to the observed data from the OD survey and the estimate data from the Gravity model applied in this same area. The results showed that the estimates from the GDA Model are as accurate as from the Gravity Model. It was observed that the GDA Model presents advantages in relation to the Gravity Model because instead of using traffic survey data, which often is expensive and difficult to get, it uses dwellers and land use information, which is periodically collected from government researches, making it easy for government agencies to obtain this information.

Made available in DSpace on 2016-03-22T17:26:07Z (GMT). No. of bitstreams: 1 Andre-Vinicius.pdf: 1143939 bytes, checksum: 6c38530394bdd70a84905edf6570f0b9 (MD5) Previous issue date: 2008-07-31 / Piaget s Theory of Social Exchanges has been used as the basis for interaction analysis in Multiagent Systems. These interactions are understood as processes of service exchanges between pairs of agents followed by the the evaluation of those services by the agents involved in the processes, producing values of social exchanges. The values emerged form those evaluations are of qualitative nature, that is, subjective values influenced by different aspects related to the internal nature of the agents or effects of the external environment. One of these aspects is the behavioral analysis of the agents in the evaluation process according to their personality traits. In a social exchange process, an agent assigns a value to its investment for performing a service to another agent, and the latter gives a value for its satisfaction in having received such a service. Subsequently, values of debits and credits are also generated, allowing for future exchanges. In this context, this work considers that the agents may assume different personality traits, which lead them to different attitudes concerning the exchanges they choose to perform, the way they evaluate the exchanges or the ways they manage their debits and credits. In the literature, there are some studies on the evaluation of social exchange values, either representing exchange values as numerical intervals (range of values) to simulate their qualitative nature, or obtaining those values using functions over parameters of objective or subjective nature, used for evaluation of exchanged services. In this work, we consider a qualitative method for evaluating social exchanges, considering only the material values of investment and satisfaction, based on Fuzzy Logic. The Fuzzy Logic is justified in this context, since it aims to model the human reasoning and the decision-making in a complex, subjective, incomplete environment, considering uncertainty and inaccuracy. In this dissertation, a service is defined as a set of attributes, whose evaluation based on fuzzy logic, considering different factors of personality, allows us to infer about the fuzzy values of that service, either related to the investment value (by the agent that performs the service) or to the satisfaction value (by the agent that receives the service). The fuzzy equations of material equilibrium in the two stages of social exchanges are also analyzed / A Teoria das Trocas Sociais de Piaget tem sido utilizada como base para a análise de interações em Sistemas Multiagente. Estas interações são compreendidas como processos de trocas de serviços entre pares de agentes seguidos da avaliação destes serviços por parte dos agentes envolvidos, produzindo valores de trocas sociais. Os valores de trocas derivados desta avaliação são de natureza qualitativa, isto é, valores subjetivos influenciados por diferentes aspectos relacionados à natureza interna dos agentes ou efeitos externos do ambiente. Um destes aspectos é a análise comportamental dos agentes no processo de avaliação conforme seus traços de personalidade. Em um processo de troca social, um agente atribui um valor ao seu investimento na realização de um serviço para outro agente e este último atribui um valor de satisfação por ter recebido tal serviço. Posteriormente, são gerados valores de débitos e créditos, que permitirão a realização de trocas futuras. Neste contexto, o presente trabalho considera que os agentes assumem diferentes traços de personalidades, o que os induzem a diferentes atitudes referentes às trocas que optam por realizar, formas como avaliam as trocas ou ainda as formas como administram seus débitos e créditos. Na literatura, alguns trabalhos realizam a avaliação dos valores de trocas sociais, sejam representando os valores de trocas como intervalos numéricos (faixas de valores), para simular sua natureza qualitativa, ou obtendo-os através de funções sobre parâmetros de natureza objetiva ou subjetiva, utilizadas para avaliação dos serviços trocados. Neste trabalho, considera-se um método qualitativo para avaliação de trocas sociais, considerando somente os valores materiais de investimento e satisfação, com base na Lógica Fuzzy. A Lógica Fuzzy justificase neste contexto, pois tem como objetivo modelar de forma aproximada o raciocínio humano e a tomada de decisões em um ambiente complexo, subjetivo, incompleto, de incerteza e imprecisão. Nesta dissertação, define-se um serviço como um conjunto de atributos, cuja avaliação baseada na Lógica Fuzzy, considerando diferentes fatores de personalidades, permite inferir sobre os valores fuzzy desse serviço, sejam com relação ao valor de investimento (por parte do agente que faz o serviço) ou de satisfação (por parte daquele que recebe o serviço). As equações fuzzy de equilíbrio material nos dois estágios de trocas sociais são também analisadas

Planners are well developed tools in computer science, but their role is rather limited in games. We decided to test the possibilities of writing such a game around them. Proving that freely available, general purpose planning systems are worthy alternatives to custom made solutions could open a new path to small developers and popularize a new kind of gameplay powered by these tools. We attempted to exploit planners in two roles, in the development, to partially automate the level design process; and in the gameplay as a decision making tool for the acting agents. Our program is a puzzle game, more precisely an anticipation game, where the player has to foresee the future actions of the acting agents, then discover the pitfalls where they are heading. Using this knowledge he can modify their environment and force them to a desired outcome. A part of our program is a generator of such game challenges. We came to a conclusion that within some limitations planners are capable of creating believable agent behavior and while not all decisions can be handed over to the planning systems, they can lighten the task of the level designer.

Made available in DSpace on 2015-04-29T15:10:48Z (GMT). No. of bitstreams: 1 ALEXANDRE PASSITO.pdf: 3822416 bytes, checksum: 4f278e2830ed590e916983c979c90872 (MD5) Previous issue date: 2012-12-04 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Autonomous networking research to applies intelligent agent and multiagent systems theory to network controlling mechanisms. Deploying such autonomous and rational entities in the network can improve its behavior in the presence of very dynamic and complex control scenarios. Unfortunately, building agent-based mechanisms for networks is not an easy task. The main difficulty is to create concise knowledge representations about network domains and reasoning mechanisms to deal with them. Furthermore, the Internet makes the design of multiagent systems for network controlling a challenging activity involving the modeling of different participants with diverse beliefs and intentions. Such type of system often poses scalability problems due to the lack of incentives for cooperation between administrative domains. Finally, as the current structure of the Internet often prevents innovation, constructed autonomous networking mechanisms are not fully deployed in large scale scenarios. The Software-Defined Networking (SDN) paradigm is in the realm of Future Internet efforts. In the SDN paradigm, packet forwarding hardware is controlled by software running as a separated control plane. Management software uses an open protocol to program the owtables in different switches and routers. This work presents a general discussion about the integration of autonomous networks and software-defined networks. Based on the knowledge offered by this discussion, it presents a framework that provides autonomy to SDN domains allowing them to act cooperatively when deployed in scenarios with distributed management. Two case studies are presented for important open issues in the Internet: (1) the problem of mitigating DDoS attacks when thousands of attackers perform malicious packet ooding and SDN domains must cooperate to cope with packet filtering at the source; (2) the problem of network traffic management when multiple domains must cooperate and modify routing primitives. / A pesquisa em redes autônomas aplica a teoria de agentes inteligentes e sistemas multiagente em mecanismos de controle de redes. Implantar esse mecanismos autônomos e racionais na rede pode melhorar seu comportamento na presença de cenários de controle muito complexos e dinâmicos. Infelizmente, a construção de mecanismos baseados em agentes para redes não é uma tarefa fácil. A principal dificuldade é criar representações concisas de conhecimento sobre os domínios de redes e mecanismos de raciocínio para lidar com elas. Além disso, a Internet faz com que o projeto de sistemas multiagente para o controle da rede seja uma atividade intrincada envolvendo a modelagem de diferentes participantes com diversas crenças e intenções. Esses tipos de sistemas geralmente apresentam problemas de escalabilidade devido à falta de incentivos para cooperação entre domínios administrativos. Finalmente, como a estrutura corrente da Internet geralmente impede inovações, mecanismos de redes autônomas construídos não são totalmente implantados em cenários de larga escala. O paradigma das redes definidas por software (SDN) está na esfera dos esforços da Internet do Futuro. No paradigma SDN, o hardware de repasse de pacotes é controlado por software sendo executado como um plano de controle separado. Softwares de gerenciamento utilizam um protocolo aberto que programa as tabelas de uxo em diferentes switches e roteadores. Este trabalho apresenta uma discussão geral sobre a integração de redes autônomas e redes definidas por software. Baseado no conhecimento oferecido por essa discussão, é apresentado um arcabouço que provê autonomia para domínios SDN, permitindo que eles atuem cooperativamente quando implantados em cenários com gerenciamento distribuído. Dois estudos de caso são apresentados para importantes questões em aberto na Internet: (1) o problema da mitigação de ataques DDoS quando milhares de atacantes realizam inundação por pacotes e os domínios SDN precisam cooperar para lidar com o filtro de pacotes na origem; (2) o problema do gerenciamento de tráfego da rede quando múltiplos domínios devem cooperar e realizar modificações nas primitivas de roteamento de redes.

Biomimetic flapping-wing vehicles have attracted recent interest because of their numerous potential military and civilian applications. In this dissertation is described the design of a multi-agent adaptive controller for such a vehicle. This controller is responsible for estimating the vehicle pose (position and orientation) and then generating four parameters needed for split-cycle control of wing movements to correct pose errors. These parameters are produced via a subsumption architecture rule base. The control strategy is fault tolerant. Using an online learning process, an agent continuously monitors the vehicle's behavior and initiates diagnostics if the behavior has degraded. This agent can then autonomously adapt the rule base if necessary. Each rule base is constructed using a combination of extrinsic and intrinsic evolution. Details of the vehicle, the multi-agent system architecture, agent task scheduling, rule base design, and vehicle control are provided.

Notre contribution dans le cadre de cette thèse est la proposition d'une nouvelle procédure de réservation de ressources à l'avance dans les réseaux IP mobiles et sans fil. Cette procédure fait appel à un nouvel objet nommé MSpec (Mobility Specification) qui représente les futures localisations du terminal mobile. Nous avons proposé un format pour cet objet ainsi qu'un profil de mobilité pour les utilisateurs mobiles qui inclut l'objet MSpec. Ce profil de mobilité découle de l'analyse du comportement de l'utilisateur durant une phase d'observation. Nous avons proposé, également, une extension de ce profil afin de pouvoir gérer le handover vertical (passage d'une technologie d'accès à une autre). Durant la phase d'observation, l'utilisateur est nouveau et le système ne peut donc pas réserver de ressources à l'avance car il ne connaît pas le profil de mobilité de l'utilisateur, et par conséquent le contenu de l'objet MSpec. Sans réservation de ressources à l'avance, nous utilisons la technologie Agent afin d'améliorer la qualité de service demandée par l'utilisateur mobile. Le rôle des agents, dans cette phase, est d'adapter le handover horizontal (passage d'une cellule à une autre en utilisant la même technologie d'accès) et le handover vertical aux besoins de qualité de service de l'utilisateur.

Ce travail de thèse, mené sur deux thématiques : les réseaux ambiants et la simulation multi-agent, a pour contexte l'étude des interactions entre le fonctionnement des réseaux ambiants (réseaux pair-à-pair et réseaux mobiles ad hoc networks) et les comportements de leurs usagers (mobilité, partage d'un service, etc.). Pour étudier ces phénomènes, nous avons mis en lumière le besoin de réutiliser, de coupler et de faire interagir des outils de modélisation et de simulation provenant de domaines scientifiques différents (réseaux informatiques, simulations sociales) afin d'intégrer simultanément plusieurs niveaux d'abstraction dans l'étude menée. Cette problématique de réutilisation et de couplage de modèles (la multi-modélisation) et de simulation (interopérabilité de simulateurs) n'est pas propre aux seuls réseaux ambiants et celle-ci s'inscrit dans le domaine plus vaste de l'étude des systèmes complexes. Cette thèse se propose d'aborder les questions de réutilisation et de couplage des outils de modélisation et de simulation sous l'angle des systèmes multi-agents et d'inscrire les solutions à la fois d'ingénierie logicielle, de simulation distribuée, de multi-modélisation dans un cadre multi-agent générique et homogène : le méta-modèle AA4MM. L'idée fondatrice est de créer une société de modèles, de simulateurs et de logiciels de simulation (que l'on nommera blocs MSL) afin d'intégrer plusieurs niveaux d'abstraction dans une même modélisation et simulation. AA4MM propose une approche multi-agent homogène qui permet de facilement réutiliser des blocs MSL, de les rendre interopérable et de les coupler de manière modulaire. AA4MM permet également au modélisateur de clairement spécifier les changements d'échelles. AA4MM propose une méthode de simulation totalement décentralisée. Au niveau des aspects théoriques du méta-modèle AA4MM, nous avons proposé une preuve formelle de l'algorithme de simulation décentralisée. Nous avons également appliqué AA4MM à un cas d'étude pédagogique en couplant ensemble plusieurs instances de NetLogo (un outil de simulation répandu). Nous avons également appliqué AA4MM aux réseaux ambiants et à notre question initiale sur les influences mutuelles entre performances du réseau et comportements des usagers. Dans ce contexte, nous avons pu réutiliser des simulateurs existants qui n'étaient pas prévus pour interagir afin d'aborder les phénomènes d'influences mutuelles entre performances des réseaux et comportements de leurs usagers.

Recent work has shown humanoid robots with spinal columns, instead of rigid torsos, benefit from both better balance and an increased ability to absorb external impact. Similarly, snake robots have shown promise as a viable option for exploration in confined spaces with limited human access, such as during power plant maintenance. Both spines and snakes, as well as hyper-redundant manipulators, can simplify to a model of a system with multiple links. The multi-link inverted pendulum is a well known benchmark problem in control systems due to its ability to accommodate varying model complexity. Such a system is useful for testing new learning algorithms or laying the foundation for autonomous control of more complex devices such as robotic spines and multi-segmented arms which currently use traditional control methods or are operated by humans. It is often easy to view these systems as single-agent learners due to the high level of interaction among the segments. However, as the number of links in the system increases, the system becomes harder to control. This work replaces the centralized learner with a team of coevolved agents. The use of a multiagent approach allows for control of larger systems. The addition of transfer learning not only increases the learning rate, but also enables the training of larger teams which were previously infeasible due to extended training times. The results presented support these claims by examining neuro-evolutionary control of 3-, 6-, and 12-link systems with nominal conditions as well as with sensor noise, actuator noise, and the addition of more complex physics. / Graduation date: 2012

Les systèmes complexes sont présents partout dans notre environnement : internet, réseaux de distribution d'électricité, réseaux de transport. Ces systèmes ont pour caractéristiques d'avoir un grand nombre d'entités autonomes, des structures dynamiques, des échelles de temps et d'espace différentes, ainsi que l'émergence de phénomènes. Ce travail de thèse se focalise sur la problématique du contrôle de tels systèmes. Il s'agit de déterminer, à partir d'une perception partielle de l'état du système, quelle(s) actions(s) effectuer pour éviter ou au contraire favoriser certains états globaux du système. Cette problématique pose plusieurs questions difficiles : pouvoir évaluer l'impact au niveau collectif d'actions appliqués au niveau individuel, modéliser la dynamique d'un système hétérogène (plusieurs comportements différents en interaction), évaluer la qualité des estimations issues de la modélisation de la dynamique du système. Nous proposons une architecture de contrôle selon une approche " equation-free ". Nous utilisons un modèle multi-agents pour évaluer l'impact global d'actions de contrôle locales avant d'appliquer la plus pertinente. Associée à cette architecture, une plateforme a été développée pour confronter ces idées à l'expérimentation dans le cadre d'un phénomène simulé de " free-riding " dans les réseaux d'échanges de fichiers pair à pair. Nous avons montré que cette approche permettait d'amener le système dans un état où une majorité de pairs partagent alors que les conditions initiales (sans intervention) feraient évoluer le système vers un état où aucun pair ne partage. Nous avons également expérimenté avec différentes configurations de l'architecture pour identifier les différents moyens d'améliorer ses performances.