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1
Lau, Pik Lik Billy. "Interdependence between agents in multi agent systems". Thesis, Curtin University, 2014. http://hdl.handle.net/20.500.11937/439.
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Interdependence relationships have defined the foundation of cooperation between agents but limited by existing protocols. As a consequence, the idle agents are not able to join and benefit through it. First, the inter-relationship has been studied and certified for the purpose of securing mutual gains. Next, the join coalition mechanism is proposed to help idle agents to join existing macroscopic and microscopic coalitions which are based on the goals compatibilities, budget and trust
2
Dinu, Razvan. "Web Agents : towards online hybrid multi-agent systems". Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20126/document.
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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 WebMulti-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
3
Cardoso, Rafael Cau? "A decentralised online multi-agent planning framework for multi-agent systems". Pontif?cia Universidade Cat?lica do Rio Grande do Sul, 2018. http://tede2.pucrs.br/tede2/handle/tede/8048.
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Sistemas multiagentes freq?entemente cont?m ambientes complexos e din?micos, nos quais os planos dos agentes podem falhar a qualquer momento durante a execu??o do sistema. Al?m disso, novos objetivos podem aparecer para os quais n?o existem nenhum plano dispon?vel. T?cnicas de planejamento s?o bem adequadas para lidar com esses problemas. H? uma quantidade extensa de pesquisa em planejamento centralizado para um ?nico agente, por?m, at? ent?o planejamento multiagente n?o foi completamente explorado na pr?tica. Plataformas multiagentes tipicamente proporcionam diversos mecanismos para coordena??o em tempo de execu??o, frequentemente necess?rios em planejamento online. Neste contexto, planejamento multiagente descentralizado pode ser eficiente e eficaz, especialmente em dom?nios fracamente acoplados, al?m de garantir algumas propriedades importantes em sistemas de agentes como privacidade e autonomia. N?s abordamos esse problema ao apresentar uma t?cnica para planejamento multiagente online que combina aloca??o de objetivos, planejamento individual utilizando rede de tarefas hier?rquicas (HTN), e coordena??o em tempo de execu??o para apoiar a realiza??o de objetivos sociais em sistemas multiagentes. Especificamente, n?s apresentamos um framework chamado Decentralised Online Multi-Agent Planning (DOMAP). Experimentos com tr?s dom?nios fracamente acoplados demonstram que DOMAP supera quatro planejadores multiagente do estado da arte com respeito a tempo de planejamento e tempo de execu??o, particularmente nos problemas mais dif?ceis.
Multi-agent systems often contain dynamic and complex environments where agents? course of action (plans) can fail at any moment during execution of the system. Furthermore, new goals can emerge for which there are no known plan available in any of the agents? plan library. Automated planning techniques are well suited to tackle both of these issues. Extensive research has been done in centralised planning for singleagents, however, so far multi-agent planning has not been fully explored in practice. Multi-agent platforms typically provide various mechanisms for runtime coordination, which are often required in online planning (i.e., planning during runtime). In this context, decentralised multi-agent planning can be efficient as well as effective, especially in loosely-coupled domains, besides also ensuring important properties in agent systems such as privacy and autonomy. We address this issue by putting forward an approach to online multi-agent planning that combines goal allocation, individual Hierarchical Task Network (HTN) planning, and coordination during runtime in order to support the achievement of social goals in multi-agent systems. In particular, we present a planning and execution framework called Decentralised Online Multi-Agent Planning (DOMAP). Experiments with three loosely-coupled planning domains show that DOMAP outperforms four other state-of-the-art multi agent planners with regards to both planning and execution time, particularly in the most difficult problems.
4
Easwaran, Aneurin Maatchiman. "Federation in multi-agent systems". Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.430853.
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Raimondi, Franco. "Model checking multi-agent systems". Thesis, University College London (University of London), 2006. http://discovery.ucl.ac.uk/5627/.
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A multi-agent system (MAS) is usually understood as a system composed of interacting autonomous agents. In this sense, MAS have been employed successfully as a modelling paradigm in a number of scenarios, especially in Computer Science. However, the process of modelling complex and heterogeneous systems is intrinsically prone to errors: for this reason, computer scientists are typically concerned with the issue of verifying that a system actually behaves as it is supposed to, especially when a system is complex. Techniques have been developed to perform this task: testing is the most common technique, but in many circumstances a formal proof of correctness is needed. Techniques for formal verification include theorem proving and model checking. Model checking techniques, in particular, have been successfully employed in the formal verification of distributed systems, including hardware components, communication protocols, security protocols. In contrast to traditional distributed systems, formal verification techniques for MAS are still in their infancy, due to the more complex nature of agents, their autonomy, and the richer language used in the specification of properties. This thesis aims at making a contribution in the formal verification of properties of MAS via model checking. In particular, the following points are addressed: • Theoretical results about model checking methodologies for MAS, obtained by extending traditional methodologies based on Ordered Binary Decision Diagrams (OBDDS) for temporal logics to multi-modal logics for time, knowledge, correct behaviour, and strategies of agents. Complexity results for model checking these logics (and their symbolic representations). • Development of a software tool (MCMAS) that permits the specification and verification of MAS described in the formalism of interpreted systems. • Examples of application of MCMAS to various MAS scenarios (communication, anonymity, games, hardware diagnosability), including experimental results, and comparison with other tools available.
6
Huang, Zhan. "Mutation for multi-agent systems". Thesis, University of York, 2016. http://etheses.whiterose.ac.uk/19270/.
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Although much progress has been made in engineering multi-agent systems (MAS), many issues remain to be resolved. One issue is that there is a lack of techniques that can adequately evaluate the effectiveness (fault detection ability) of tests or testing techniques for MAS. Another is that there are no systematic approaches to evaluating the impact of possible semantic changes (changes in the interpretation of agent programs) on agents' behaviour and performance. This thesis introduces syntactic and semantic mutation to address these two issues. Syntactic mutation is a technique that systematically generates variants ("syntactic mutants") of a description (usually a program) following a set of rules ("syntactic mutation operators"). Each mutant is expected to simulate a real description fault, therefore, the effectiveness of a test set can be evaluated by checking whether it can detect each simulated fault, in other words, distinguish the original description from each mutant. Although syntactic mutation is widely considered very effective, only limited work has been done to introduce it into MAS. This thesis extends syntactic mutation for MAS by proposing a set of syntactic mutation operators for the Jason agent language and showing that they can be used to generate real faults in Jason agent programs. By contrast, semantic mutation systematically generates variant interpretations ("semantic mutants") of a description following a set of rules ("semantic mutation operators"). Semantic mutation has two uses: to evaluate the effectiveness of a test set by simulating faults caused by misunderstandings of how the description is interpreted, and to evaluate the impact of possible semantic changes on agents' behaviour and performance. This thesis, for the first time, proposes semantic mutation for MAS, more specifically, for three logic based agent languages, namely Jason, GOAL and 2APL. It proposes semantic mutation operators for these languages, shows that the operators for Jason can represent real misunderstandings and are practically useful.
7
Haque, Musad Al. "Biologically inspired heterogeneous multi-agent systems". Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37138.
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Many biological systems are known to accomplish complex tasks in a decentralized, robust, and scalable manner - characteristics that are desirable to the coordination of engineered systems as well. Inspired by nature, we produce coordination strategies for a network of heterogenous agents and in particular, we focus on intelligent collective systems. Bottlenose dolphins and African lions are examples of intelligent collective systems since they exhibit sophisticated social behaviors and effortlessly transition between functionalities. Through preferred associations, specialized roles, and self-organization, these systems forage prey, form alliances, and maintain sustainable group sizes. In this thesis, we take a three-phased approach to bioinspiration: in the first phase, we produce agent-based models of specific social behaviors observed in nature. The goal of these models is to capture the underlying biological phenomenon, yet remain simple so that the models are amenable to analysis. In the second phase, we produce bio-inspired algorithms that are based on the simple biological models produced in the first phase. Moreover, these algorithms are developed in the context of specific coordination tasks, e.g., the multi-agent foraging task. In the final phase of this work, we tailor these algorithms to produce coordination strategies that are ready to be deployed in target applications.
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Gill, Martin L. "Combining MAS and P2P systems : the Agent Trees Multi-Agent System (ATMAS)". Thesis, University of Stirling, 2005. http://hdl.handle.net/1893/108.
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The seamless retrieval of information distributed across networks has been one of the key goals of many systems. Early solutions involved the use of single static agents which would retrieve the unfiltered data and then process it. However, this was deemed costly and inefficient in terms of the bandwidth since complete files need to be downloaded when only a single value is often all that is required. As a result, mobile agents were developed to filter the data in situ before returning it to the user. However, mobile agents have their own associated problems, namely security and control. The Agent Trees Multi-Agent System (AT-MAS) has been developed to provide the remote processing and filtering capabilities but without the need for mobile code. It is implemented as a Peer to Peer (P2P) network of static intelligent cooperating agents, each of which control one or more data sources. This dissertation describes the two key technologies have directly influenced the design of ATMAS, Peer-to-Peer (P2P) systems and Multi-Agent Systems (MAS). P2P systems are conceptually simple, but limited in power, whereas MAS are significantly more complex but correspondingly more powerful. The resulting system exhibits the power of traditional MAS systems while retaining the simplicity of P2P systems. The dissertation describes the system in detail and analyses its performance.
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Rahwan, Iyad. "Interest-based negotiation in multi-agent systems". Connect to thesis, 2004. http://repository.unimelb.edu.au/10187/2885.
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Software systems involving autonomous interacting software entities (or agents) present new challenges in computer science and software engineering. A particularly challenging problem is the engineering of various forms of interaction among agents. Interaction may be aimed at enabling agents to coordinate their activities, cooperate to reach common objectives, or exchange resources to better achieve their individual objectives. This thesis is concerned with negotiation: a process through which multiple self-interested agents can reach agreement over the exchange of scarce resources. In particular, I focus on settings where agents have limited or uncertain information, precluding them from making optimal individual decisions. I demonstrate that this form of bounded-rationality may lead agents to sub-optimal negotiation agreements. I argue that rational dialogue based on the exchange of arguments can enable agents to overcome this problem. Since agents make decisions based on particular underlying reasons, namely their interests, beliefs and planning knowledge, then rational dialogue over these reasons can enable agents to refine their individual decisions and consequently reach better agreements. I refer to this form of interaction as “interested-based negotiation.” (For complete abstract open document)
10
Seyboth, Georg Sebastian. "Event-based Controlfor Multi-Agent Systems". Thesis, KTH, Reglerteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-105117.
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In this thesis, a novel approach to the average consensus problem for multi-agent systems is followed. A new event-based control strategy is proposed, which incorporates event-based scheduling of state measurement broadcasts over the network. The control-laws are based on the resulting piecewise constant functions of these measurement values. This facilitates implementation on digital platforms such as microprocessors and reduces the number of interagent communications over the network. Starting from a basic problem setup with singleintegrator agents, fixed undirected connected communication topologies, and no time-delays, the novel strategy is developed. Different triggering conditions guaranteeing convergence to an adjustable region around the average consensus point or asymptotic convergence to this point, respectively, are discussed. Numerical simulations show the effectiveness of this approach, outperforming classical time-scheduled implementations of the consensus protocol in terms of load on the communication medium. Furthermore the problem class is extended to networks with directed communication links, switching topologies, and time-delays in the communication as well as to agents with double-integrator dynamics. As an illustrative example, the novel strategy is applied to a formation control problem of non-holonomic mobile robots in the plane.
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Kouvaros, Panagiotis. "Parameterised verification for multi-agent systems". Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/33793.
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In the past ten years several methods have been put forward for the efficient model checking of multiagent systems against agent-based specifications. Yet, since the number of states is exponential in the number of agents in the system, the model checking problem remains intractable for systems of many agents. This is particularly problematic when wishing to reason about unbounded systems where the number of components is not known at design time. Systems ranging from robotic swarms to e-commerce applications constitute typical examples in which the number of participants is independent of the design process. This thesis develops parameterised model checking techniques for the validation of multiagent systems irrespectively of the number of the agents present. To do this, a semantics that captures parameterised, synchronous multiagent systems and one that models parameterised, interleaved multiagent systems are introduced. Both semantics extend interpreted systems in a parameterised setting where the number of agents is the parameter. Parameterised model checking techniques for the semantical classes introduced are developed. A sound and complete cutoff methodology is studied for parameterised interpreted systems. A sound but incomplete cutoff procedure for parameterised interleaved interpreted systems is also studied. While the latter procedure is in exponential space, three notable subclasses are isolated and more effective verification techniques are put forward. The algorithms proposed are shown to be sound. For one class the decidability of the verification problem is shown and a complete cutoff procedure is discussed. Finally, the model checker MCMAS-P is introduced. The tool supports the verification of unbounded multiagent systems against temporal-epistemic specifications. MCMAS-P implements the procedures here developed; the procedure invoked depends on the properties of the system under examination. Experimental results obtained on cache coherence protocols, mutual exclusion protocols, swarm foraging algorithms, and swarm aggregation algorithms are reported.
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Juziuk, Joanna. "Design Patterns for Multi-Agent Systems". Thesis, Linnéuniversitetet, Institutionen för datavetenskap, fysik och matematik, DFM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-20481.
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Design patterns document a field's systematic knowledge derived from experiences. Despite the vast body of work in the field of multi-agent systems (MAS), design patterns for MAS are not popular among software practitioners. As MAS have features that are widely considered as key to engineering complex distributed applications, for example in manufacturing, robotics, ecommerce, traffic control and coordination, science simulations, it is important to provide a clear overview of existing patterns to make this knowledge accessible. To that end, a systematic literature review was performed covering the main publication venues of the field since 1998, resulting in 206 patterns. The study shows that (1) there is a lack of a standard template for documenting design patterns for MAS, which hampers the use of patterns by practitioners, (2) associations between patterns are poorly described, which results in a lack of overview of the pattern space, (3) patterns for MAS have been used for a variety of application domains, which underpins their high potential for practitioners, and (4) classifications of design patterns for MAS are bounded to specific pattern catalogs, a more holistic view on the pattern space is missing. From the study, a number of guidelines is outlined that are important for future work on design patterns for MAS and their adoption in practice.
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Johansson, Stefan J. "On Coordination in Multi-agent Systems". Doctoral thesis, Karlskrona : Department of Software Engineering & Computer Science, Blekinge Institute of Technology, 2002. http://www.bth.se/fou/Forskinfo.nsf/Sok/c7187f25921663c9c1256bb5005fc376!OpenDocument.
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Hu, Yuebing, i 胡跃冰. "Consensus control of multi-agent systems". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B4658657X.
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Bennett, Robin Catherine. "Implementing norm-governed multi-agent systems". Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/18994.
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The actions and interactions of independently acting agents in a multi-agent system must be managed if the agents are to function effectively in their shared environment. Norms, which define the obligatory, prohibited and permitted actions for an agent to perform, have been suggested as a possible method for regulating the actions of agents. Norms are local rules designed to govern the actions of individual agents whilst also allowing the agents to achieve a coherent global behaviour. However, there appear to be very few instances of norm-governed multi-agent systems beyond theoretical examples. We describe an implementation strategy for allowing autonomous agents to take a set of norms into account when determining their actions. These norms are implemented using directives, which are local rules specifying actions for an agent to perform depending on its current state. Agents using directives are implemented in a simulation test bed, called Sinatra. Using Sinatra, we investigate the ability of directives to manage agent actions. We begin with directives to manage agent interactions. We find that when agents rely on only local rules they will encounter situations where the local rules are unable to achieve the desired global behaviour. We show how a centralised control mechanism can be used to manage agent interactions that are not successfully handled by directives. Controllers, with a global view of the interaction, instruct the individual agents how to act. We also investigate the use of an existing planning tool to implement the resolution mechanism of a controller. We investigate the ability of directives to coordinate the actions of agents in order to achieve a global objective more effectively. Finally, we present a case study of how directives can be used to determine the actions of autonomous mobile robots.
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Roberts, Mark Jonathan. "Social laws for multi-agent systems". Thesis, University of Liverpool, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437526.
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Abu, Bakar Badril. "Autonomous multi-agent reconfigurable control systems". Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/351346/.
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This thesis is an investigation of methods and architectures for autonomous multi-agent reconfigurable controllers. As part of the analysis two components are looked at: the fault detection and diagnosis (FDD) component and the controller reconfiguration (CR) component. The FDD component detects and diagnoses faults. The CR component on the other hand, adapts or changes the control architecture to accommodate the fault. The problem is to synchronize or integrate these two components in the overall structure of a control system. A novel approach is proposed. A multiagent architecture is used to interface between the two components. This method allows the system to be viewed as a modular structure. Three types of agent are defined. A planner agent Ap, a monitor agent Am and a control agent Ac. The monitor agent takes the role of the FDD component. The planner and control agents on the other hand take the roles of CR component. The planner decides which controller to use and passes it on to Ac. It also decides on the parameter settings of the system and changes it accordingly. It belongs to the reactive agent category. The planner agent's internal architecture maps its sensor data directly to actions using a pre-set rule based conditional logic. It was decided that this architecture would reduce the overall complexity of the system. The monitor agent Am belongs to the learning agent category. It uses an algorithm called adaptive resonance theory neural network or ART-NN to autonomously categorize system faults. Am then informs the other agents of the fault status. ART-NN was chosen due to the fact that it does not need to be trained with sample data and learns to categorize data patterns on the fly. This allows Am to detect unmodelled system faults. The control agent Ac also belongs to the learning agent category. It uses a multiagent reinforcement learning algorithm to learn a controller for the system at hand. Once a suitable controller has been learnt, the parameters of the controller are passed to Ap for it to be stored in its memory and learning is terminated. During control execution mode, controller parameters are sent to Ac from Ap. The novel approach is demonstrated on a case study. Our laboratory-built 4-wheeled skid-steering vehicle complete with sensors is designed as a way of demonstration. Several faults are simulated and the response of the demo system is analyzed.
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Such, Aparicio José Miguel. "ENHANCING PRIVACY IN MULTI-AGENT SYSTEMS". Doctoral thesis, Universitat Politècnica de València, 2011. http://hdl.handle.net/10251/13023.
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La pérdida de privacidad se está convirtiendo en uno de los mayores problemas
en el mundo de la informática. De hecho, la mayoría de los usuarios
de Internet (que hoy en día alcanzan la cantidad de 2 billones de usuarios
en todo el mundo) están preocupados por su privacidad. Estas preocupaciones
también se trasladan a las nuevas ramas de la informática que están
emergiendo en los ultimos años. En concreto, en esta tesis nos centramos en
la privacidad en los Sistemas Multiagente. En estos sistemas, varios agentes
(que pueden ser inteligentes y/o autónomos) interactúan para resolver problemas.
Estos agentes suelen encapsular información personal de los usuarios
a los que representan (nombres, preferencias, tarjetas de crédito, roles, etc.).
Además, estos agentes suelen intercambiar dicha información cuando interactúan entre ellos. Todo esto puede resultar en pérdida de privacidad para
los usuarios, y por tanto, provocar que los usuarios se muestren adversos a
utilizar estas tecnologías.
En esta tesis nos centramos en evitar la colección y el procesado de información personal en Sistemas Multiagente. Para evitar la colección de información, proponemos un modelo para que un agente sea capaz de decidir
qué atributos (de la información personal que tiene sobre el usuario al que
representa) revelar a otros agentes. Además, proporcionamos una infraestructura
de agentes segura, para que una vez que un agente decide revelar
un atributo a otro, sólo este último sea capaz de tener acceso a ese atributo,
evitando que terceras partes puedan acceder a dicho atributo. Para evitar el
procesado de información personal proponemos un modelo de gestión de las
identidades de los agentes. Este modelo permite a los agentes la utilización
de diferentes identidades para reducir el riesgo del procesado de información. Además, también describimos en esta tesis la implementación de dicho
modelo en una plataforma de agentes.Such Aparicio, JM. (2011). ENHANCING PRIVACY IN MULTI-AGENT SYSTEMS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/13023
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Sánchez, Anguix Víctor. "Complex negotiations in multi-agent systems". Doctoral thesis, Universitat Politècnica de València, 2013. http://hdl.handle.net/10251/21570.
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Los sistemas multi-agente (SMA) son sistemas distribuidos donde entidades autónomas llamadas
agentes, ya sean humanos o software, persiguen sus propios objetivos. El paradigma de SMA ha
sido propuesto como la aproximación de modelo apropiada para aplicaciones como el comercio
electrónico, los sistemas multi-robot, aplicaciones de seguridad, etc. En la comunidad de SMA, la
visión de sistemas multi-agente abiertos, donde agentes heterogéneos pueden entrar y salir del
sistema dinámicamente, ha cobrado fuerza como paradigma de modelado debido a su relación
conceptual con tecnologías como la Web, la computación grid, y las organizaciones virtuales.
Debido a la heterogeneidad de los agentes, y al hecho de dirigirse por sus propios objetivos, el
conflicto es un fenómeno candidato a aparecer en los sistemas multi-agente.
En los últimos años, el término tecnologías del acuerdo ha sido usado para referirse a todos aquellos
mecanismos que, directa o indirectamente, promueven la resolución de conflictos en sistemas
computacionales como los sistemas multi-agente. Entre las tecnologías del acuerdo, la negociación
automática ha sido propuesta como uno de los mecanismos clave en la resolución de conflictos
debido a su uso análogo en la resolución de conflictos entre humanos. La negociación automática
consiste en el intercambio automático de propuestas llevado a cabo por agentes software en nombre
de sus usuarios. El objetivo final es conseguir un acuerdo con todas las partes involucradas.
Pese a haber sido estudiada por la Inteligencia Artificial durante años, distintos problemas todavía
no han sido resueltos por la comunidad científica todavía. El principal objetivo de esta tesis es
proponer modelos de negociación para escenarios complejos donde la complejidad deriva de (1) las
limitaciones computacionales o (ii) la necesidad de representar las preferencias de múltiples
individuos. En la primera parte de esta tesis proponemos un modelo de negociación bilateral para el
problema deSánchez Anguix, V. (2013). Complex negotiations in multi-agent systems [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/21570
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Torreño, Lerma Alejandro. "Cooperative planning in multi-agent systems". Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/65815.
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[EN] Automated planning is a centralized process in which a single planning entity, or agent, synthesizes a course of action, or plan, that satisfies a desired set of goals from an initial situation. A Multi-Agent System (MAS) is a distributed system where a group of autonomous agents pursue their own goals in a reactive, proactive and social way.
Multi-Agent Planning (MAP) is a novel research field that emerges as the integration of automated planning in MAS. Agents are endowed with planning capabilities and their mission is to find a course of action that attains the goals of the MAP task. MAP generalizes the problem of automated planning in domains where several agents plan and act together by combining their knowledge, information and capabilities.
In cooperative MAP, agents are assumed to be collaborative and work together towards the joint construction of a competent plan that solves a set of common goals. There exist different methods to address this objective, which vary according to the typology and coordination needs of the MAP task to solve; that is, to which extent agents are able to make their own local plans without affecting the activities of the other agents.
The present PhD thesis focuses on the design, development and experimental evaluation of a general-purpose and domain-independent resolution framework that solves cooperative MAP tasks of different typology and complexity. More precisely, our model performs a multi-agent multi-heuristic search over a plan space. Agents make use of an embedded search engine based on forward-chaining Partial Order Planning to successively build refinement plans starting from an initial empty plan while they jointly explore a multi-agent search tree. All the reasoning processes, algorithms and coordination protocols are fully distributed among the planning agents and guarantee the preservation of the agents' private information.
The multi-agent search is guided through the alternation of two state-based heuristic functions. These heuristic estimators use the global information on the MAP task instead of the local projections of the task of each agent. The experimental evaluation shows the effectiveness of our multi-heuristic search scheme, obtaining significant results in a wide variety of cooperative MAP tasks adapted from the benchmarks of the International Planning Competition.[ES] La planificación automática es un proceso centralizado en el que una única entidad de planificación, o agente, sintetiza un curso de acción, o plan, que satisface un conjunto deseado de objetivos a partir de una situación inicial. Un Sistema Multi-Agente (SMA) es un sistema distribuido en el que un grupo de agentes autónomos persiguen sus propias metas de forma reactiva, proactiva y social. La Planificación Multi-Agente (PMA) es un nuevo campo de investigación que surge de la integración de planificación automática en SMA. Los agentes disponen de capacidades de planificación y su propósito consiste en generar un curso de acción que alcance los objetivos de la tarea de PMA. La PMA generaliza el problema de planificación automática en dominios en los que diversos agentes planifican y actúan conjuntamente mediante la combinación de sus conocimientos, información y capacidades. En PMA cooperativa, se asume que los agentes son colaborativos y trabajan conjuntamente para la construcción de un plan competente que resuelva una serie de objetivos comunes. Existen distintos métodos para alcanzar este objetivo que varían de acuerdo a la tipología y las necesidades de coordinación de la tarea de PMA a resolver; esto es, hasta qué punto los agentes pueden generar sus propios planes locales sin afectar a las actividades de otros agentes. La presente tesis doctoral se centra en el diseño, desarrollo y evaluación experimental de una herramienta independiente del dominio y de propósito general para la resolución de tareas de PMA cooperativa de distinta tipología y nivel de complejidad. Particularmente, nuestro modelo realiza una búsqueda multi-agente y multi-heurística sobre el espacio de planes. Los agentes hacen uso de un motor de búsqueda embebido basado en Planificación de Orden Parcial de encadenamiento progresivo para generar planes refinamiento de forma sucesiva mientras exploran conjuntamente el árbol de búsqueda multiagente. Todos los procesos de razonamiento, algoritmos y protocolos de coordinación están totalmente distribuidos entre los agentes y garantizan la preservación de la información privada de los agentes. La búsqueda multi-agente se guía mediante la alternancia de dos funciones heurísticas basadas en estados. Estos estimadores heurísticos utilizan la información global de la tarea de PMA en lugar de las proyecciones locales de la tarea de cada agente. La evaluación experimental muestra la efectividad de nuestro esquema de búsqueda multi-heurístico, que obtiene resultados significativos en una amplia variedad de tareas de PMA cooperativa adaptadas a partir de los bancos de pruebas de las Competición Internacional de Planificación.
[CAT] La planificació automàtica és un procés centralitzat en el que una única entitat de planificació, o agent, sintetitza un curs d'acció, o pla, que satisfau un conjunt desitjat d'objectius a partir d'una situació inicial. Un Sistema Multi-Agent (SMA) és un sistema distribuït en el que un grup d'agents autònoms persegueixen les seues pròpies metes de forma reactiva, proactiva i social. La Planificació Multi-Agent (PMA) és un nou camp d'investigació que sorgeix de la integració de planificació automàtica en SMA. Els agents estan dotats de capacitats de planificació i el seu propòsit consisteix en generar un curs d'acció que aconseguisca els objectius de la tasca de PMA. La PMA generalitza el problema de planificació automàtica en dominis en què diversos agents planifiquen i actúen conjuntament mitjançant la combinació dels seus coneixements, informació i capacitats. En PMA cooperativa, s'assumeix que els agents són col·laboratius i treballen conjuntament per la construcció d'un pla competent que ressolga una sèrie d'objectius comuns. Existeixen diferents mètodes per assolir aquest objectiu que varien d'acord a la tipologia i les necessitats de coordinació de la tasca de PMA a ressoldre; és a dir, fins a quin punt els agents poden generar els seus propis plans locals sense afectar a les activitats d'altres agents. La present tesi doctoral es centra en el disseny, desenvolupament i avaluació experimental d'una ferramenta independent del domini i de propòsit general per la resolució de tasques de PMA cooperativa de diferent tipologia i nivell de complexitat. Particularment, el nostre model realitza una cerca multi-agent i multi-heuristica sobre l'espai de plans. Els agents fan ús d'un motor de cerca embegut en base a Planificació d'Ordre Parcial d'encadenament progressiu per generar plans de refinament de forma successiva mentre exploren conjuntament l'arbre de cerca multiagent. Tots els processos de raonament, algoritmes i protocols de coordinació estan totalment distribuïts entre els agents i garanteixen la preservació de la informació privada dels agents. La cerca multi-agent es guia mitjançant l'aternança de dues funcions heurístiques basades en estats. Aquests estimadors heurístics utilitzen la informació global de la tasca de PMA en lloc de les projeccions locals de la tasca de cada agent. L'avaluació experimental mostra l'efectivitat del nostre esquema de cerca multi-heurístic, que obté resultats significatius en una ampla varietat de tasques de PMA cooperativa adaptades a partir dels bancs de proves de la Competició Internacional de Planificació.
Torreño Lerma, A. (2016). Cooperative planning in multi-agent systems [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/65815
TESIS
Premiado
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Mukherjee, Srijita. "Formation Control of Multi-Agent Systems". Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1011784/.
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Formation control is a classical problem and has been a prime topic of interest among the scientific community in the past few years. Although a vast amount of literature exists in this field, there are still many open questions that require an in-depth understanding and a new perspective. This thesis contributes towards exploring the wide dimensions of formation control and implementing a formation control scheme for a group of multi-agent systems. These systems are autonomous in nature and are represented by double integrated dynamics. It is assumed that the agents are connected in an undirected graph and use a leader-follower architecture to reach formation when the leading agent is given a velocity that is piecewise constant. A MATLAB code is written for the implementation of formation and the consensus-based control laws are verified. Understanding the effects on formation due to a fixed formation geometry is also observed and reported. Also, a link that describes the functional similarity between desired formation geometry and the Laplacian matrix has been observed. The use of Laplacian matrix in stability analysis of the formation is of special interest.
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SANAI, DASHTI ZOHREH AL ZAHRA. "Coordination of Open Multi-Agent Systems". Doctoral thesis, Università degli Studi di Cagliari, 2022. http://hdl.handle.net/11584/333258.
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During the last decade, the problem of consensus in Multi-Agent Systems (MASs) has been studied with special emphasis on graph theoretical methods. Consensus can be regarded as a control objective in which all the agents in a network converge to (or agree “upon”) a common value. This is achieved through a given control strategy usually referred to as consensus algorithm. The consensus problem in MASs becomes more challenging in the presence of agents that can join and leave the network, hence the so-called “open” multi-agent systems. This topic is recent in the scientific literature and
quickly gaining attention. Thus, this dissertation is motivated by this topic, focusing on the consensus problem on the median consensus value and the average consensus in open multi-agent systems.
Hence, this thesis is first devoted to designing a novel distributed open average consensus protocol for multi-agent systems. The distributed algorithm tracks the average of the agents’ state despite the time-varying size and composition of the network. The research activity consists of the design and formal characterization of the convergence
properties of the algorithm. The results have been corroborated by numerical simulations.
As for the second part of the research activity, the characterization of the convergence properties of a distributed algorithm to compute and track the median value of a set of numbers in open multi-agent systems has been proposed. A continuous time formulation is considered where the state variables of the agents track with zero error the median value of a set of time-varying reference signals given as input to the agents in a time-varying, undirected network topology. The performance of the proposed protocol is considered in the framework of open multi-agent systems by proposing join and leave mechanisms, i.e., the scenario where agents may join and leave the network during the
protocol execution. One notable feature of consensus on the median value is the robustness of the median value, as opposed to the average value, with respect to abnormal or outlier state values. Non-smooth Lyapunov theory is employed to provide convergence guarantees and simple tuning rules to adjust the algorithm parameters.
Apart from studying open multi-agent systems, this dissertation also proposes a distributed scheme for transforming any connected interaction graph with a possible no integer average degree into a connected approximately random k-regular graph which is independent of the degree of the initial graph. in more details, we define some local graph transformation rules (consisting of rules for cutting, adding, and moving edges) and provide a distributed implementation. In the resulting process, a random regular graph is obtained while the agents observe and modify only the local structure of the
network. As such, the network achieves high expansion ratios and algebraic connectivity, which provide robustness to various structural and functional perturbations.
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DeJong, Paul. "COALITION FORMATION IN MULTI-AGENT UAV SYSTEMS". Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2712.
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Coalitions are collections of agents that join together to solve a common problem that either cannot be solved individually or can be solved more efficiently as a group. Each individual agent has capabilities that can benefit the group when working together as a coalition. Typically, individual capabilities are joined together in an additive way when forming a coalition. This work will introduce a new operator that is used when combining capabilities, and suggest that the behavior of the operator is contextual, depending on the nature of the capability itself. This work considers six different capabilities of Unmanned Air Vehicles (UAV) and determines the nature of the new operator in the context of each capability as coalitions (squadrons) of UAVs are formed. Coalitions are formed using three different search algorithms, both with and without heuristics: Depth-First, Depth-First Iterative Deepening, and Genetic Algorithm (GA). The effectiveness of each algorithm is evaluated. Multi agent-based UAV simulation software was developed and used to test the ideas presented. In addition to coalition formation, the software aims to address additional multi-agent issues such as agent identity, mutability, and communication as applied to UAV systems, in a realistic simulated environment. Social potential fields provide a means of modeling a clustering attractive force at the same time as a collision-avoiding repulsive force, and are used by the simulation to maintain aircraft position relative to other UAVs.M.S.Cp.E.
Department of Electrical and Computer Engineering
Engineering and Computer Science
Computer Engineering
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Srivastava, Sanjeev Kumar. "Multi-Agent System for predictive reconfiguration of Shipboard Power Systems". Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/1593.
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The electric power systems in U.S. Navy ships supply energy to sophisticated systems for weapons, communications, navigation and operation. The reliability and survivability of the Shipboard Power System (SPS) are critical to the mission of a surface combatant ship, especially under battle conditions. In the event of battle, various weapons might attack a ship. When a weapon hits the ship it can cause severe damage to the electrical system on the ship. This damage can lead to de-energization of critical loads on a ship that can eventually decrease a ships ability to survive the attack. It is very important, therefore, to maintain availability of energy to the connected loads that keep the power systems operational. Technology exists that enables the detection of an incoming weapon and prediction of the geographic area where the incoming weapon will hit the ship. This information can then be used to take reconfiguration actions before the actual hit so that the actual damage caused by the weapon hit is reduced. The Power System Automation Lab (PSAL) has proposed a unique concept called "Predictive Reconfiguration" which refers to performing reconfiguration of a ships power system before a weapon hit to reduce the potential damage to the electrical system caused by the impending weapon hit. The concept also includes reconfiguring the electrical system to restore power to as much of the healthy system as possible after the weapon hit. This dissertation presents a new methodology for Predictive Reconfiguration of a Shipboard Power System (SPS). This probabilistic approach includes a method to assess the damage that will be caused by a weapon hit. This method calculates the expected probability of damage for each electrical component on the ship. Also a heuristic method is included, which uses the expected probability of damage to determine reconfiguration steps to reconfigure the ships electrical network to reduce the damage caused by a weapon hit. This dissertation also presents a modified approach for performing a reconfiguration for restoration after the weapon hits the system. In this modified approach, an expert system based restoration method restores power to loads de-energized due to the weapon hit. These de-energized loads are restored in a priority order. The methods were implemented using multi-agent technology. A test SPS model based on the electrical layout of a non-nuclear surface combatant ship was presented. Complex scenarios representing electrical casualties caused due to a weapon hit, on the test SPS model, were presented. The results of the Predictive Reconfiguration methodology for complex scenarios were presented to illustrate the effectiveness of the developed methodology.
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Poutakidis, David Alexander, i davpout@cs rmit edu au. "Debugging Multi-Agent Systems With Design Documents". RMIT University. Computer Science and Information Technology, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20081205.114106.
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Debugging multi-agent systems, which are concurrent, distributed, and consist of complex components is difficult, yet crucial. The development of these complex systems is supported by agent-oriented software engineering methodologies which utilise agents as the central design metaphor. The systems that are developed are inherently complex since the components of these systems may interact in flexible and sophisticated ways and traditional debugging techniques are not appropriate. Despite this, very little effort has been applied to developing appropriate debugging tools and techniques. Debugging multi-agent systems without good debugging tools is highly impractical and without suitable debugging support developing and maintaining multi-agent systems will be more difficult than it need be. In this thesis we propose that the debugging process can be supported by following an agent-oriented design methodology, and then using the developed design artifacts in the debugging phase. We propose a domain independent debugging framework which comprises the developed processes and components that are necessary in using design artifacts as debugging artifacts. Our approach is to take a non-formal design artifact, such as an AUML protocol design, and encode it in a machine interpretable manner such that the design can be used as a model of correct system behaviour. These models are used by a run-time debugging system to compare observed behaviour against specified behaviour. We provide details for transforming two design artifact types into equivalent debugging artifacts and show how these can be used to detect bugs. During a debugging episode in which a bug has been identified our debugging approach can provide detailed information about the possible reason for the bug occurring. To determine if this information was useful in helping to debug programs we undertook a thorough empirical study and identified that use of the debugging tool translated to an improvement in debugging performance. We conclude that the debugging techniques developed in this thesis provide effective debugging support for multi-agent systems and by having an extensible framework new design artifacts can be explored and as translations are developed they can be added to the debugging system.
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Sharma, Naveen, i n/a. "A multi agent system framework for.NET". University of Canberra. Information Sciences & Engineering, 2005. http://erl.canberra.edu.au./public/adt-AUC20060726.153250.
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This thesis presents an approach to modeling Multi Agent Systems (MAS). A framework and its implementation are presented as an extension to .NET. A number of definitions of agents are evaluated for the purpose of a broad understanding of the term software agent. Software agent has been defined in MAS context and its characteristics are identified and implemented. Motivation factors for building framework for MAS have been discussed. A number of existing technologies are discussed and evaluated. A number of agent systems previously developed are also being discussed in the middle part of the thesis. A model software agent has been defined and its characteristics are divided in two basic categories essential and optional. Its implementation has been distributed into different components throughout the MAS framework. Some of these characteristics are jointly implemented by a number of components and others responsibility rest on the individual components. Detail working of the MAS framework (i.e. what to do, when to do) is explained as guide to develop MAS using MAS framework. The protocols followed by the framework components to make communication possible between them are discussed at components level. The required information for developing MAS using MAS framework are also discussed. It answers the why, when and how questions in regards to using MAS framework A case study on Dynamic Truck Scheduling (DTS) system is discussed, designed and implemented using the MAS framework. DTS System has been used as a prototype application to test and evaluate the framework. DTS also represents a model problem that can be answered by using MAS; complete in-depth details about the problem statement are discussed. It also discusses the design and implementation of the solution along with the test results of the framework. Possible future expansion is presented in light of a number of limitations known of the MAS framework. The code working behind the different components of the MAS framework is given in appendices. Some important standards of XML that are used to pass information between agents and MAS framework components are also given in the format of tables.
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Steiner, David. "Belief change functions for multi-agent systems /". [S.l.] : [s.n.], 2009. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000277034.
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Sorensen, Gerrit Addison N. "A Flexible Infrastructure for Multi-Agent Systems". Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd875.pdf.
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French, Stevan J. "Analyzing personnel retention utilizing multi-agent systems". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2000. http://handle.dtic.mil/100.2/ADA386919.
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Thesis (M.S. in Modeling, Virtual Environments and Simulation (MOVES))--Naval Postgraduate School, Dec. 2000.Thesis advisors, Michael Zyda, John Hiles. Includes bibliographical references (p. 123-126). Also available online.
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Wang, Lei. "Some approximation algorithms for multi-agent systems". Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42726.
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This thesis makes a number of contributions to the theory of approximation algorithm design for multi-agent systems. In particular, we focus on two research directions. The first direction is to generalize the classical framework of combinatorial optimization to the submodular setting, where we assume that each agent has a submodular cost function. We show hardness results from both the information-theoretic and computational aspects for several fundamental optimization problems in the submodular setting, and provide matching approximation algorithms for most of them. The second direction is to introduce game-theoretic issues to approximation algorithm design. Towards this direction, we study the application of approximation algorithms in the theory of truthful mechanism design. We study both the standard objectives of revenue and social welfare, by designing efficient algorithms that satisfy the requirement of truthfulness and guarantee approximate optimality.
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Pedersen, Sindre Sønvisen. "Decentralized Decision Making in Multi-Agent Systems". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for teknisk kybernetikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-13461.
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The literature in the feld of multi-agent manufacturing control predom-inantly presents qualitative arguments to motivate its usage. This workpresents quantitative meaning to some of these arguments. The work alsodiscusses the control structuring process and puts it into perspective withmulti-agent control. A suitable example for the analysis of multi-agent con-trol is developed. A two layered approach for the control of this exampleprocess is proposed and it is shown that agents can be used in both of theselayers. An ad-hoc analysis is made of the top layer and simulation resultsshows that a distributed control approach introduces an optimality gap whencompared to a centralized approach. Further simulation results show thata layered approach to multi-agent control for the proposed process improvesoverall performance by increasing agent coordination.To date there has been a lack of industry adoption of multi-agent tech-nologies. The industry seems to favor control approaches that are well testedand with quantifiable evidence supporting their efficiency. The developmentof simulators that capture the full complexity of manufacturing processes isa time consuming task. The example process proposed in this work onlycaptures some core dynamics. Further work on presenting more quantifiablearguments for the use of multi-agent control is thus motivated throughoutthe thesis.The ideas presented in this thesis are included in the article MAS formanufacturing control: A layered case study by Pedersen et al. The articleis aimed for submission to the AAMAS 2012 conference in Valencia.
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Gonzalez, Pavel. "Model checking GSM-based multi-agent systems". Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/39038.
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Business artifacts are a growing topic in service oriented computing. Artifact systems include both data and process descriptions at interface level thereby providing more sophisticated and powerful service inter-operation capabilities. The Guard-Stage-Milestone (GSM) language provides a novel framework for specifying artifact systems that features declarative descriptions of the intended behaviour without requiring an explicit specification of the control flow. While much of the research is focused on the design, deployment and maintenance of GSM programs, the verification of this formalism has received less attention. This thesis aims to contribute to the topic. We put forward a holistic methodology for the practical verification of GSM-based multi-agent systems via model checking. The formal verification faces several challenges: the declarative nature of GSM programs; the mechanisms for data hiding and access control; and the infinite state spaces inherent in the underlying data. We address them in stages. First, we develop a symbolic representation of GSM programs, which makes them amenable to model checking. We then extend GSM to multi-agent systems and map it into a variant of artifact-centric multi-agent systems (AC-MAS), a paradigm based on interpreted systems. This allows us to reason about the knowledge the agents have about the artifact system. Lastly, we investigate predicate abstraction as a key technique to overcome the difficulty of verifying infinite state spaces. We present a technique that lifts 3-valued abstraction to epistemic logic and makes GSM programs amenable to model checking against specifications written in a quantified version of temporal-epistemic logic. The theory serves as a basis for developing a symbolic model checker that implements SMT-based, 3-valued abstraction for GSM-based multi-agent systems. The feasibility of the implementation is demonstrated by verifying GSM programs for concrete applications from the service community.
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Lu, Gehao. "Neural trust model for multi-agent systems". Thesis, University of Huddersfield, 2011. http://eprints.hud.ac.uk/id/eprint/17817/.
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Introducing trust and reputation into multi-agent systems can significantly improve the quality and efficiency of the systems. The computational trust and reputation also creates an environment of survival of the fittest to help agents recognize and eliminate malevolent agents in the virtual society. The thesis redefines the computational trust and analyzes its features from different aspects. A systematic model called Neural Trust Model for Multi-agent Systems is proposed to support trust learning, trust estimating, reputation generation, and reputation propagation. In this model, the thesis innovates the traditional Self Organizing Map (SOM) and creates a SOM based Trust Learning (STL) algorithm and SOM based Trust Estimation (STE) algorithm. The STL algorithm solves the problem of learning trust from agents' past interactions and the STE solve the problem of estimating the trustworthiness with the help of the previous patterns. The thesis also proposes a multi-agent reputation mechanism for generating and propagating the reputations. The mechanism exploits the patterns learned from STL algorithm and generates the reputation of the specific agent. Three propagation methods are also designed as part of the mechanism to guide path selection of the reputation. For evaluation, the thesis designs and implements a test bed to evaluate the model in a simulated electronic commerce scenario. The proposed model is compared with a traditional arithmetic based trust model and it is also compared to itself in situations where there is no reputation mechanism. The results state that the model can significantly improve the quality and efficacy of the test bed based scenario. Some design considerations and rationale behind the algorithms are also discussed based on the results.
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Wernstedt, Fredrik. "Multi-Agent Systems for District Heating Management". Licentiate thesis, Karlskrona : Blekinge Institute of Technology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-00258.
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This thesis investigates the applicability of multi-agent systems as a control approach for district heating systems. The consumers, i.e., the heat exchange systems, in current district heating systems are purely reactive devices and have typically no communication capabilities. They are only able to make local decisions without taking into account the global situation in the system. In this work, the possibilities of a new type of heat exchanger systems that has an open software environment and communication capabilities are explored. Operators of district heating systems have several, often conflicting, goals, e.g., to satisfy the demand of the customers and to minimize production costs. Major concerns are how to cope with the uncertainty caused by discrepancies between the estimated and actual customer demand, and the temporal constraints imposed by the relatively long production and distribution times (up to 24 hours). The approach studied in this thesis is to equip each consumer with an agent that makes predictions of future needs and to form clusters of consumers within which it is possible to redistribute resources fast and at a low cost. The agents have two fundamental goals: the local goal, which is to satisfy the customers’ needs, and the global goal, which is to improve the overall performance of the system by cooperating with the other agents in the cluster. Results from a simulation study indicate that the suggested approach makes it possible to reduce production while maintaining the quality of service. The study also show that it is possible to control the trade-off between quality-of-service and degree of surplus production. In another study, a smallscale experiment in a controlled physical environment, two agent-based approaches are evaluated and compared to existing technologies. The experiment shows that it is possible to automatically load balance a small district heating network using agent technology. Finally, a generalized formal characterization of the problem space under investigation is provided, i.e., production and logistics network management, together with a preliminary evaluation of the applicability of the suggested multi-agent system approach for this general problem area.
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Zhang, Peng. "Multi-agent Systems in Diabetic Health Care". Licentiate thesis, Karlskrona : Blekinge Institute of Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-00263.
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This thesis discusses how Multi-agent Systems (MAS) should be designed in the context of diabetic health care. Three fields are touched: computer science, socio-psychology and systems science. Agent Technology is the core technology in the research. Theories from socio-psychology and systems science are applied to facilitate the discussion about computer agents. As the integration of socio-psychology and systems science, Activity Systems Theory is introduced to give a synthesized description of MAS. Laws and models are introduced with benefits on both individual agent and agent communities. Cybernetics from systems science and knowledge engineering from computer science are introduced to approach the design and implementation of the individual agent architecture. A computer agent is considered intelligent if it is capable of reactivity, proactivity and social activity. Reactivity and proactivity can be realized through a cybernetic approach. Social activity is much more complex, since it considers MAS coordination. In this thesis, I discuss it from the perspectives of socio-psychology. The hierarchy and motivation thinking from Activity Systems Theory is introduced to the MAS coordination. To behave intelligent, computer agents should work with knowledge. Knowledge is considered as a run-time property of a group of agents (MAS). During the MAS coordination, agents generate new information through exchanging the information they have. A knowledge component is needed in agent’s architecture for the knowledge related tasks. In my research, I adopt CommonKADS methodology for the design and implementation of agent’s knowledge component. The contribution of this research is twofold: first, MAS coordination is described with perspectives from socio-psychology. According to Activity Systems Theory, MAS is hierarchically organized and driven by the motivation. This thesis introduces a motivation-driven mechanism for the MAS coordination. Second, the research project Integrated Mobile Information Systems for health care (IMIS) indicates that the diabetic health care can be improved by introducing agent-based services to the care-providers and care-receivers. IMIS agents are designed with capabilities of information sharing, organization coordination and task delegation. To perform these tasks, the IMIS agents interact with each other based on the coordination mechanism that is discussed above.
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Hussain, Shahid, i Hassan Shabbir. "Directory scalability in multi-agent based systems". Thesis, Blekinge Tekniska Högskola, Avdelningen för programvarusystem, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-3110.
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Simulation is one approach to analyze and model the real world complex problems. Multi-agent based systems provide a platform to develop simulations based on the concept of agent-oriented programming. In multi-agent systems, the local interaction between agents contributes to the emergence of the global phenomena by getting the result of the simulation runs. In MABS systems, interaction is one common aspect for all agents to perform their tasks. To interact with each other the agents require yellow page services from the platform to search for other agents. As more and more agents perform searches on this yellow page directory, there is a decrease in the performance due to a central bottleneck. In this thesis, we have investigated multiple solutions for this problem. The most promising solution is to integrate distributed shared memory with the directory systems. With our proposed solution, empirical analysis shows a statistically significant increase in performance of the directory service. We expect this result to make a considerable contribution to the state of the art in multiagent platforms.
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Tomic, Ivana. "Distributed LQR control of multi-agent systems". Thesis, City, University of London, 2016. http://openaccess.city.ac.uk/15883/.
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The thesis develops optimal control methods for designing distributed cooperative control schemes in multi-agent networks. First, the model of a completely connected multi-agent network is presented, consisting of identical dynamically decoupled agents controlled by a centralized LQR (Linear Quadratic Regulator) based controller. The structure of the solution, as well as controller's spectral and robustness properties are presented. A special case of centralized control where the optimal solution for the whole network can be constructed from the solution of single agent LQR system is given. The problem is extended to distributed control where the special structure is imposed onto the information flow between agents and only local interaction is considered. A systematic method is given for computing the performance loss of various distributed control configurations relative to the performance of the optimal centralized controller. Necessary and sufficient conditions are derived for which a distributed control configuration pattern arising from the optimal centralized solution does not entail loss of performance if the initial state vector lies is a certain subspace of state-space which is identified. It is shown that these conditions are always satisfied for systems with communication/control networks corresponding to complete graphs with a single link removed. The procedure is extended for the purposes of analysing the performance loss of an arbitrary distributed configuration. Cost increase due to decentralisation is quantified by introducing three cost measures corresponding to the worst-case, best-case and average directions in which the initial state of the system lies. Finally, a cooperative scheme is presented for controlling arbitrary formations of low speed experimental UAVs (Unmanned Aerial Vehicles) based on a distributed LQR design methodology. Each UAV acts as an independent agent in the formation and its dynamics are described by a 6-DOF (six degrees-offreedom) nonlinear model. This is linearised for control design purposes around an operating point corresponding to straight flight conditions and simulated for longitudinal motion. It is shown that the proposed controller stabilises the overall formation and can control effectively the nonlinear multi-agent system. Also, it is illustrated via numerous simulations that the system provides reference tracking and that is robust to environmental disturbances such as nonuniform wind gusts acting on a formation of UAVs and to the loss of communication between two neighbouring UAVs.
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Wen, Guoguang. "Distributed cooperative control for multi-agent systems". Phd thesis, Ecole Centrale de Lille, 2012. http://tel.archives-ouvertes.fr/tel-00818774.
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Cette thèse considère principalement trois problèmes dans le domaine du contrôle distribué coopératif des systèmes multi-agents(SMA): le consensus, la navigation en formation et le maintien en formation d'un groupe d'agents lorsqu'un agent disparait. Nous proposons 3 algorithmes pour résoudre le problème du calcul distribué d'un consensus à partir de l'approche leadeur-suiveur dans le contexte SMA à dynamique non-linéaire. La référence est définie comme un leader virtuel dont on n'obtient, localement, que les données de position et de vitesse. Pour résoudre le problème du suivi par consensus pour les SMA à dynamique non-linéaire, nous considérons le suivi par consensus pour SMA de premier ordre. On propose des résultats permettant aux suiveurs de suivre le leadeur virtuel en temps fini en ne considérant que les positions des agents. Ensuite, nous considérons le suivi par consensus de SMA de second. Dans le cas de la planification de trajectoire et la commande du mouvement de la formation multi-agents. L'idée est d'amener la formation, dont la dynamique est supposée être en 3D, d'une configuration initiale vers une configuration finale (trouver un chemin faisable en position et orientation) en maintenant sa forme tout le long du chemin en évitant les obstacles. La stratégie proposée se décompose en 3 étapes. Le problème du Closing-Rank se traduit par la réparation d'une formation rigide multi-agents "endommagée" par la perte de l'un de ses agents. Nous proposons 2 algorithmes d'autoréparation systématique pour récupérer la rigidité en cas de perte d'un agent. Ces réparations s'effectuent de manière décentralisée et distribuée n'utilisant que des informations de voisinage.
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Chli, Maria. "Convergence and interactivity of multi-agent systems". Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427951.
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Shah, N. H. "Exception diagnosis in open multi-agent systems". Thesis, Coventry University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425240.
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Nguyen, Nguyen. "Reasoning about resource-bounded multi-agent systems". Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/11851/.
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The thesis presents logic-based formalisms for modelling and reasoning about resource-bounded multi-agent systems. In the field of multi-agent system, it is well-known that temporal logics such as CTL and ATL are powerful tools for reasoning about multi-agent systems. However, there is no natural way to utilise these logics for expressing and reasoning about properties of multi-agent systems where actions of agents require resources to be able to perform. This thesis extends logics including Computational Tree Logic (CTL), Coalition Logic (CL) and Alternating-time Temporal Logic (ATL) which have been used to reasoning about multi-agent systems so that the extended ones have the power to specify and to reason about properties of resource-bounded multi-agent systems. While the extension of CTL is adapted for specifying and reasoning about properties of systems of resource-bounded reasoners where the resources are explicitly memory, communication and time, the extensions of CL and ATL are generalised so that any resource-bounded multi-agent system can be modelled, specified and reasoned about. For each of the logics, we describe the range of resource-bounded multi-agent systems they can account for and axiomatisation systems for reasoning which are proved to be sound and complete. Moreover, we also study the satisfiability problem of these logics.
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Kaufman, Maike Jennifer. "Local decision-making in multi-agent systems". Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:e8ebc360-906d-4733-9f24-f3ed98735e89.
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This thesis presents a new approach to local decision-making in multi-agent systems with varying amounts of communication. Here, local decision-making refers to action choices which are made in a decentralized fashion by individual agents based on the information which is locally available to them. The work described here is set within the multi-agent decision process framework. Unreliable, faulty or stochastic communication patterns present a challenge to these settings which usually rely on precomputed, centralised solutions to control individual action choices. Various approximate algorithms for local decision-making are developed for scenarios with and without sequentiality. The construction of these techniques is based strongly on methods of Bayesian inference. Their performance is tested on synthetic benchmark scenarios and compared to that of a more conservative approach which guarantees coordinated action choices as well as a completely decentralized solution. In addition, the method is applied to a surveillance task based on real-world data. These simulation results show that the algorithms presented here can outperform more traditional approaches in many settings and provide a means for flexible, scalable decision-making in systems with varying information exchange between agents.
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Neville, Brendan J. "Simulating social relations in multi-agent systems". Thesis, Imperial College London, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.542940.
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Chen, Xudong. "Multi-Agent Systems with Reciprocal Interaction Laws". Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11424.
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In this thesis, we investigate a special class of multi-agent systems, which we call reciprocal multi-agent (RMA) systems. The evolution of agents in a RMA system is governed by interactions between pairs of agents. Each interaction is reciprocal, and the magnitude of attraction/repulsion depends only on distances between agents. We investigate the class of RMA systems from four perspectives, these are two basic properties of the dynamical system, one formula for computing the Morse indices/co-indices of critical formations, and one formation control model as a variation of the class of RMA systems. An important aspect about RMA systems is that there is an equivariant potential function associated with each RMA system so that the equations of motion of agents are actually a gradient flow. The two basic properties about this class of gradient systems we will investigate are about the convergence of the gradient flow, and about the question whether the associated potential function is generically an equivariant Morse function. We develop systematic approaches for studying these two problems, and establish important results. A RMA system often has multiple critical formations and in general, these are hard to locate. So in this thesis, we consider a special class of RMA systems whereby there is a geometric characterization for each critical formation. A formula associated with the characterization is developed for computing the Morse index/co-index of each critical formation. This formula has a potential impact on the design and control of RMA systems. In this thesis, we also consider a formation control model whereby the control of formation is achieved by varying interactions between selected pairs of agents. This model can be interpreted in different ways in terms of patterns of information flow, and we establish results about the controllability of this control system for both centralized and decentralized problems.Engineering and Applied Sciences
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Janicke, Helge. "The development of secure multi-agent systems". Thesis, De Montfort University, 2007. http://hdl.handle.net/2086/4809.
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Lees, Michael Harold. "Adaptive optimistic simulation of multi-agent systems". Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431334.
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Stein, Sebastian. "Flexible service provisioning in multi-agent systems". Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/265840/.
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Service-oriented computing is an increasingly popular approach for providing applications, computational resources and business services over highly distributed and open systems (such as the Web, computational Grids and peer-to-peer systems). In this approach, service providers advertise their offerings by means of standardised computer-readable descriptions, which can then be used by software applications to discover and consume appropriate services without human intervention. However, despite active research in service infrastructures, and in service discovery and composition mechanisms, little work has recognised that services are offered by inherently autonomous and self-interested entities. This autonomy implies that providers may choose not to honour every service request, demand remuneration for their efforts, and, in general, exhibit uncertain behaviour. This uncertainty is especially problematic for the service consumers when services are part of complex workflows, as is common in many application domains, such as bioinformatics, large-scale data analysis and processing, and commercial supply-chain management. In order to address this uncertainty, we propose a novel algorithm for provisioning services for complex workflows (i.e., for selecting suitable services for the constituent tasks of a workflow). This algorithm uses probabilistic performance information about providers to reason about service uncertainty and its impact on the overall workflow. Furthermore, our approach actively mitigates this uncertainty by employing two key techniques. First, it proactively provisions redundant services for particularly critical or failure-prone tasks (thus increasing the probability of success). Second, it recovers dynamically from service failures by re-provisioning services at run-time (without necessarily receiving explicit failure messages). Unlike existing work in this area, our algorithm employs principled decision-theoretic techniques to determine which services to provision, whether to introduce redundant services and when to re-provision failed services. In doing so, it explicitly balances the cost of provisioning with the expected value of the workflow. To show how our algorithm applies to a range of common service-oriented systems, we consider a variety of different scenarios in this thesis. More specifically, we first examine environments where the consumer lacks specific knowledge to differentiate between distinct service providers, as is common in highly dynamic and open systems. Despite this lack of detailed knowledge, we demonstrate how the consumer can use redundancy and dynamic re-provisioning to influence the outcome of a workflow and to deal with uncertainty. Then, we look into systems where the consumer has more specific knowledge about highly heterogeneous providers. While existing work has concentrated on selecting the single best provider for each workflow task, we show that a consumer can often improve its performance by provisioning multiple providers with different qualities for a single task. Finally, we discuss how our algorithm can be adapted for systems where consumers and providers reach explicit service contracts in advance. In this context, we are the first to propose a gradual provisioning approach, whereby the consumer negotiates contracts for some tasks in advance, but leaves the negotiation of others to a later time. This approach allows the consumer to better react to uncertain service outcomes and to avoid paying reservation fees that are later lost when services fail. Throughout this thesis, we compare our approach empirically to current provisioning algorithms. In doing so, we demonstrate that our approach typically achieves a significantly higher utility for the service consumer than approaches that do not reason about uncertainty, that rely on fixed levels of redundancy or service time-outs, and approaches that select single services to achieve the optimal balance of various performance characteristics. Furthermore, we show that these results hold over a large range of environments and workflow types and that our algorithm copes well even in highly uncertain environments where most services fail. As our approach relies on fast heuristics to solve a problem that is known to be intractable, it scales well to larger workflows with hundreds of tasks and thousands of providers. Finally, where it is tractable to compute an optimal solution, we show empirically that our algorithm achieves a high utility that is within 87% or more of the optimal.
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Russo, Francesco. "Abstraction in model checking multi-agent systems". Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9294.
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This thesis presents existential abstraction techniques for multi-agent systems preserving temporal-epistemic specifications. Multi-agent systems, defined in the interpreted system frameworks, are abstracted by collapsing the local states and actions of each agent. The goal of abstraction is to reduce the state space of the system under investigation in order to cope with the state explosion problem that impedes the verification of very large state space systems. Theoretical results show that the resulting abstract system simulates the concrete one. Preservation and correctness theorems are proved in this thesis. These theorems assure that if a temporal-epistemic formula holds on the abstract system, then the formula also holds on the concrete one. These results permit to verify temporal-epistemic formulas in abstract systems instead of the concrete ones, therefore saving time and space in the verification process. In order to test the applicability, usefulness, suitability, power and effectiveness of the abstraction method presented, two different implementations are presented: a tool for data-abstraction and one for variable-abstraction. The first technique achieves a state space reduction by collapsing the values of the domains of the system variables. The second technique performs a reduction on the size of the model by collapsing groups of two or more variables. Therefore, the abstract system has a reduced number of variables. Each new variable in the abstract system takes values belonging to a new domain built automatically by the tool. Both implementations perform abstraction in a fully automatic way. They operate on multi agents models specified in a formal language, called ISPL (Interpreted System Programming Language). This is the input language for MCMAS, a model checker for multi-agent systems. The output is an ISPL file as well (with a reduced state space). This thesis also presents several suitable temporal-epistemic examples to evaluate both techniques. The experiments show good results and point to the attractiveness of the temporal-epistemic abstraction techniques developed in this thesis. In particular, the contributions of the thesis are the following ones: • We produced correctness and preservation theoretical results for existential abstraction. • We introduced two algorithms to perform data-abstraction and variable-abstraction on multi-agent systems. • We developed two software toolkits for automatic abstraction on multi-agent scenarios: one tool performing data-abstraction and the second performing variable-abstraction. • We evaluated the methodologies introduced in this thesis by running experiments on several multi-agent system examples.
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Waslander, Steven L. "Multi-agent systems design for aerospace applications /". May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Jin, Zhipu Murray Richard M. "Coordinated control for networked multi-agent systems /". Diss., Pasadena, Calif. : Caltech, 2007. http://resolver.caltech.edu/CaltechETD:etd-09182006-162259.
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