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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Web Agents : towards online hybrid multi-agent systems / Agents Web : vers des systèmes multi-agents hybrides en ligne

Dinu, Razvan 13 December 2012 (has links)
Multi-agent systems have been used in a wide range of applications from computer-based simulations and mobile robots to agent-oriented programming and intelligent systems in real environments. However, the largest environment in which software agents can interact is, without any doubt, the World Wide Web and ever since its birth agents have been used in various applications such as search engines, e-commerce, and most recently the semantic web. However, agents have yet to be used on the Web in a way that leverages the full power of artificial intelligence and multi-agent systems, which have the potential of making life much easier for humans. This thesis investigates how this can be changed, and how agents can be brought to the core of the online experience in the sense that we want people to talk and interact with agents instead of "just using yet another application or website". We analyze what makes it hard to develop intelligent agents on the web and we propose a web agent model (WAM) inspired by recent results in multi-agent systems. Nowadays, a simple conceptual model is the key for widespread adoption of new technologies and this is why we have chosen the MASQ meta-model as the basis for our approach, which provides the best compromise in terms of simplicity of concepts, generality and applicability to the web. Since until now the model was introduced only in an informal way, we also provide a clear formalization of the MASQ meta-model.Next, we identify the three main challenges that need to be addressed when building web agents: integration of bodies, web semantics and user friendliness. We focus our attention on the first two and we propose a set of principles to guide the development of what we call strong web agents. Finally, we validate our proposal through the implementation of an award winning platform called Kleenk. Our work is just a step towards fulfilling the vision of having intelligent web agents mediate the interaction with the increasingly complex World Wide Web. / Multi-agent systems have been used in a wide range of applications from computer-based simulations and mobile robots to agent-oriented programming and intelligent systems in real environments. However, the largest environment in which software agents can interact is, without any doubt, the World Wide Web and ever since its birth agents have been used in various applications such as search engines, e-commerce, and most recently the semantic web. However, agents have yet to be used on the Web in a way that leverages the full power of artificial intelligence and multi-agent systems, which have the potential of making life much easier for humans. This thesis investigates how this can be changed, and how agents can be brought to the core of the online experience in the sense that we want people to talk and interact with agents instead of "just using yet another application or website". We analyze what makes it hard to develop intelligent agents on the web and we propose a web agent model (WAM) inspired by recent results in multi-agent systems. Nowadays, a simple conceptual model is the key for widespread adoption of new technologies and this is why we have chosen the MASQ meta-model as the basis for our approach, which provides the best compromise in terms of simplicity of concepts, generality and applicability to the web. Since until now the model was introduced only in an informal way, we also provide a clear formalization of the MASQ meta-model.Next, we identify the three main challenges that need to be addressed when building web agents: integration of bodies, web semantics and user friendliness. We focus our attention on the first two and we propose a set of principles to guide the development of what we call strong web agents. Finally, we validate our proposal through the implementation of an award winning platform called Kleenk. Our work is just a step towards fulfilling the vision of having intelligent web agents mediate the interaction with the increasingly complex World Wide Web.
2

Modelování umělého života / Artificial Life Modelling

Žák, Jakub January 2009 (has links)
This paper deals with artificial life simulation by means of artificial BDI agents.This work aims to create a virtual world, to which agents are put. In system, there is 5 kinds of agents. Agent father, who rules and synchronizes the system. Next are agent worker, salesman, cop and thief. Model of the system is created by use of Prometheus methodology. The system is programed in the Jason language, which is implementation of AgentSpeak language.
3

Autonomous Systems in Society and War : Philosophical Inquiries

Johansson, Linda January 2013 (has links)
The overall aim of this thesis is to look at some philosophical issues surrounding autonomous systems in society and war. These issues can be divided into three main categories. The first, discussed in papers I and II, concerns ethical issues surrounding the use of autonomous systems – where the focus in this thesis is on military robots. The second issue, discussed in paper III, concerns how to make sure that advanced robots behave ethically adequate. The third issue, discussed in papers IV and V, has to do with agency and responsibility. Another issue, somewhat aside from the philosophical, has to do with coping with future technologies, and developing methods for dealing with potentially disruptive technologies. This is discussed in papers VI and VII. Paper I systemizes some ethical issues surrounding the use of UAVs in war, with the laws of war as a backdrop. It is suggested that the laws of war are too wide and might be interpreted differently depending on which normative moral theory is used. Paper II is about future, more advanced autonomous robots, and whether the use of such robots can undermine the justification for killing in war. The suggestion is that this justification is substantially undermined if robots are used to replace humans to a high extent. Papers I and II both suggest revisions or additions to the laws or war. Paper III provides a discussion on one normative moral theory – ethics of care – connected to care robots. The aim is twofold: first, to provide a plausible and ethically relevant interpretation of the key term care in ethics of care, and second, to discuss whether ethics of care may be a suitable theory to implement in care robots. Paper IV discusses robots connected to agency and responsibility, with a focus on consciousness. The paper has a functionalistic approach, and it is suggested that robots should be considered agents if they can behave as if they are, in a moral Turing test. Paper V is also about robots and agency, but with a focus on free will. The main question is whether robots can have free will in the same sense as we consider humans to have free will when holding them responsible for their actions in a court of law. It is argued that autonomy with respect to norms is crucial for the agency of robots. Paper VI investigates the assessment of socially disruptive technological change. The coevolution of society and potentially disruptive technolgies makes decision-guidance on such technologies difficult. Four basic principles are proposed for such decision guidance, involving interdisciplinary and participatory elements. Paper VII applies the results from paper VI – and a workshop – to autonomous systems, a potentially disruptive technology. A method for dealing with potentially disruptive technolgies is developed in the paper. / <p>QC 20130911</p>
4

Social Dimensions of Robotic versus Virtual Embodiment, Presence and Influence

Thellman, Sam January 2016 (has links)
Robots and virtual agents grow rapidly in behavioural sophistication and complexity. They become better learners and teachers, cooperators and communicators, workers and companions. These artefacts – whose behaviours are not always readily understood by human intuition nor comprehensibly explained in terms of mechanism – will have to interact socially. Moving beyond artificial rational systems to artificial social systems means having to engage with fundamental questions about agenthood, sociality, intelligence, and the relationship between mind and body. It also means having to revise our theories about these things in the course of continuously assessing the social sufficiency of existing artificial social agents. The present thesis presents an empirical study investigating the social influence of physical versus virtual embodiment on people's decisions in the context of a bargaining task. The results indicate that agent embodiment did not affect the social influence of the agent or the extent to which it was perceived as a social actor. However, participants' perception of the agent as a social actor did influence their decisions. This suggests that experimental results from studies comparing different robot embodiments should not be over-generalised beyond the particular task domain in which the studied interactions took place.
5

Large state spaces and self-supervision in reinforcement learning

Touati, Ahmed 08 1900 (has links)
L'apprentissage par renforcement (RL) est un paradigme d'apprentissage orienté agent qui s'intéresse à l'apprentissage en interagissant avec un environnement incertain. Combiné à des réseaux de neurones profonds comme approximateur de fonction, l'apprentissage par renforcement profond (Deep RL) nous a permis récemment de nous attaquer à des tâches très complexes et de permettre à des agents artificiels de maîtriser des jeux classiques comme le Go, de jouer à des jeux vidéo à partir de pixels et de résoudre des tâches de contrôle robotique. Toutefois, un examen plus approfondi de ces remarquables succès empiriques révèle certaines limites fondamentales. Tout d'abord, il a été difficile de combiner les caractéristiques souhaitables des algorithmes RL, telles que l'apprentissage hors politique et en plusieurs étapes, et l'approximation de fonctions, de manière à obtenir des algorithmes stables et efficaces dans de grands espaces d'états. De plus, les algorithmes RL profonds ont tendance à être très inefficaces en raison des stratégies d'exploration-exploitation rudimentaires que ces approches emploient. Enfin, ils nécessitent une énorme quantité de données supervisées et finissent par produire un agent étroit capable de résoudre uniquement la tâche sur laquelle il est entrainé. Dans cette thèse, nous proposons de nouvelles solutions aux problèmes de l'apprentissage hors politique et du dilemme exploration-exploitation dans les grands espaces d'états, ainsi que de l'auto-supervision dans la RL. En ce qui concerne l'apprentissage hors politique, nous apportons deux contributions. Tout d'abord, pour le problème de l'évaluation des politiques, nous montrons que la combinaison des méthodes populaires d'apprentissage hors politique et à plusieurs étapes avec une paramétrisation linéaire de la fonction de valeur pourrait conduire à une instabilité indésirable, et nous dérivons une variante de ces méthodes dont la convergence est prouvée. Deuxièmement, pour l'optimisation des politiques, nous proposons de stabiliser l'étape d'amélioration des politiques par une régularisation de divergence hors politique qui contraint les distributions stationnaires d'états induites par des politiques consécutives à être proches les unes des autres. Ensuite, nous étudions l'apprentissage en ligne dans de grands espaces d'états et nous nous concentrons sur deux hypothèses structurelles pour rendre le problème traitable : les environnements lisses et linéaires. Pour les environnements lisses, nous proposons un algorithme en ligne efficace qui apprend activement un partitionnement adaptatif de l'espace commun en zoomant sur les régions les plus prometteuses et fréquemment visitées. Pour les environnements linéaires, nous étudions un cadre plus réaliste, où l'environnement peut maintenant évoluer dynamiquement et même de façon antagoniste au fil du temps, mais le changement total est toujours limité. Pour traiter ce cadre, nous proposons un algorithme en ligne efficace basé sur l'itération de valeur des moindres carrés pondérés. Il utilise des poids exponentiels pour oublier doucement les données qui sont loin dans le passé, ce qui pousse l'agent à continuer à explorer pour découvrir les changements. Enfin, au-delà du cadre classique du RL, nous considérons un agent qui interagit avec son environnement sans signal de récompense. Nous proposons d'apprendre une paire de représentations qui mettent en correspondance les paires état-action avec un certain espace latent. Pendant la phase non supervisée, ces représentations sont entraînées en utilisant des interactions sans récompense pour encoder les relations à longue portée entre les états et les actions, via une carte d'occupation prédictive. Au moment du test, lorsqu'une fonction de récompense est révélée, nous montrons que la politique optimale pour cette récompense est directement obtenue à partir de ces représentations, sans aucune planification. Il s'agit d'une étape vers la construction d'agents entièrement contrôlables. Un thème commun de la thèse est la conception d'algorithmes RL prouvables et généralisables. Dans la première et la deuxième partie, nous traitons de la généralisation dans les grands espaces d'états, soit par approximation de fonctions linéaires, soit par agrégation d'états. Dans la dernière partie, nous nous concentrons sur la généralisation sur les fonctions de récompense et nous proposons un cadre d'apprentissage non-supervisé de représentation qui est capable d'optimiser toutes les fonctions de récompense. / Reinforcement Learning (RL) is an agent-oriented learning paradigm concerned with learning by interacting with an uncertain environment. Combined with deep neural networks as function approximators, deep reinforcement learning (Deep RL) allowed recently to tackle highly complex tasks and enable artificial agents to master classic games like Go, play video games from pixels, and solve robotic control tasks. However, a closer look at these remarkable empirical successes reveals some fundamental limitations. First, it has been challenging to combine desirable features of RL algorithms, such as off-policy and multi-step learning with function approximation in a way that leads to both stable and efficient algorithms in large state spaces. Moreover, Deep RL algorithms tend to be very sample inefficient due to the rudimentary exploration-exploitation strategies these approaches employ. Finally, they require an enormous amount of supervised data and end up producing a narrow agent able to solve only the task that it was trained on. In this thesis, we propose novel solutions to the problems of off-policy learning and exploration-exploitation dilemma in large state spaces, as well as self-supervision in RL. On the topic of off-policy learning, we provide two contributions. First, for the problem of policy evaluation, we show that combining popular off-policy and multi-step learning methods with linear value function parameterization could lead to undesirable instability, and we derive a provably convergent variant of these methods. Second, for policy optimization, we propose to stabilize the policy improvement step through an off-policy divergence regularization that constrains the discounted state-action visitation induced by consecutive policies to be close to one another. Next, we study online learning in large state spaces and we focus on two structural assumptions to make the problem tractable: smooth and linear environments. For smooth environments, we propose an efficient online algorithm that actively learns an adaptive partitioning of the joint space by zooming in on more promising and frequently visited regions. For linear environments, we study a more realistic setting, where the environment is now allowed to evolve dynamically and even adversarially over time, but the total change is still bounded. To address this setting, we propose an efficient online algorithm based on weighted least squares value iteration. It uses exponential weights to smoothly forget data that are far in the past, which drives the agent to keep exploring to discover changes. Finally, beyond the classical RL setting, we consider an agent interacting with its environments without a reward signal. We propose to learn a pair of representations that map state-action pairs to some latent space. During the unsupervised phase, these representations are trained using reward-free interactions to encode long-range relationships between states and actions, via a predictive occupancy map. At test time, once a reward function is revealed, we show that the optimal policy for that reward is directly obtained from these representations, with no planning. This is a step towards building fully controllable agents. A common theme in the thesis is the design of provable RL algorithms that generalize. In the first and the second part, we deal with generalization in large state spaces either by linear function approximation or state aggregation. In the last part, we focus on generalization over reward functions and we propose a task-agnostic representation learning framework that is provably able to solve all reward functions.

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