This thesis addresses creativity in design as a property of systems rather than an attribute of isolated individuals. It focuses on the dynamics between generative and evaluative or ascriptive processes. This is in distinction to conventional approaches to the study of creativity which tend to concentrate on the isolated characteristics of person, process and product. Whilst previous research has advanced insights on potentially creative behaviour and on the general dynamics of innovation in groups, little is known about their interaction. A systems view of creativity in design is adopted in our work to broaden the focus of inquiry to incorporate the link between individual and collective change. The work presented in this thesis investigates the relation between creativity and innovation in computational models of design as a social construct. The aim is to define and implement in computer simulations the different actors and components of a system and the rules that may determine their behaviour and interaction. This allows the systematic study of their likely characteristics and effects when the system is run over simulated time. By manipulating the experimental variables of the system at initial time the experimenter is able to extract patterns from the observed results over time and build an understanding of the different types of determinants of creative design. The experiments and findings presented in this thesis relate to artificial societies composed by software agents and the social structures that emerge from their interaction. Inasmuch as these systems aim to capture some aspects of design activity, understanding them is likely to contribute to the understanding of the target system. The first part of this thesis formulates a series of initial computational explorations on cellular automata of social influence and change agency. This simple modelling framework illustrates a number of factors that facilitate change. The potential for a designer to trigger cycles of collective change is demonstrated to depend on the combination of individual and external or situational characteristics. A more comprehensive simulation framework is then introduced to explore the link between designers and their societies based on a systems model of creativity that includes social and epistemological components. In this framework a number of independent variables are set for experimentation including characteristics of individuals, fields, and domains. The effects of these individual and situational parameters are observed in experimental settings. Aspects of relevance in the definition of creativity included in these studies comprise the role of opinion leaders as gatekeepers of the domain, the effects of social organisation, the consequences of public and private access to domain knowledge by designers, and the relation between imitative behaviour and innovation. A number of factors in a social system are identified that contribute to the emergence of phenomena that are normally associated to creativity and innovation in design. At the individual level the role of differences of abilities, persistence, opportunities, imitative behaviour, peer influence, and design strategies are discussed. At the field level determinants under inspection include group structure, social mobility and organisation, emergence of opinion leaders, established rules and norms, and distribution of adoption and quality assessments. Lastly, domain aspects that influence the interaction between designers and their social groups include the generation and access to knowledge, activities of gatekeeping, domain size and distribution, and artefact structure and representation. These insights are discussed in view of current findings and relevant modelling approaches in the literature. Whilst a number of assumptions and results are validated, others contribute to ongoing debates and suggest specific mechanisms and parameters for future experimentation. The thesis concludes by characterising this approach to the study of creativity in design as an alternative �in silico� method of inquiry that enables simulation with phenomena not amenable to direct manipulation. Lines of development for future work are advanced which promise to contribute to the experimental study of the social dimensions of design.

This thesis addresses creativity in design as a property of systems rather than an attribute of isolated individuals. It focuses on the dynamics between generative and evaluative or ascriptive processes. This is in distinction to conventional approaches to the study of creativity which tend to concentrate on the isolated characteristics of person, process and product. Whilst previous research has advanced insights on potentially creative behaviour and on the general dynamics of innovation in groups, little is known about their interaction. A systems view of creativity in design is adopted in our work to broaden the focus of inquiry to incorporate the link between individual and collective change. The work presented in this thesis investigates the relation between creativity and innovation in computational models of design as a social construct. The aim is to define and implement in computer simulations the different actors and components of a system and the rules that may determine their behaviour and interaction. This allows the systematic study of their likely characteristics and effects when the system is run over simulated time. By manipulating the experimental variables of the system at initial time the experimenter is able to extract patterns from the observed results over time and build an understanding of the different types of determinants of creative design. The experiments and findings presented in this thesis relate to artificial societies composed by software agents and the social structures that emerge from their interaction. Inasmuch as these systems aim to capture some aspects of design activity, understanding them is likely to contribute to the understanding of the target system. The first part of this thesis formulates a series of initial computational explorations on cellular automata of social influence and change agency. This simple modelling framework illustrates a number of factors that facilitate change. The potential for a designer to trigger cycles of collective change is demonstrated to depend on the combination of individual and external or situational characteristics. A more comprehensive simulation framework is then introduced to explore the link between designers and their societies based on a systems model of creativity that includes social and epistemological components. In this framework a number of independent variables are set for experimentation including characteristics of individuals, fields, and domains. The effects of these individual and situational parameters are observed in experimental settings. Aspects of relevance in the definition of creativity included in these studies comprise the role of opinion leaders as gatekeepers of the domain, the effects of social organisation, the consequences of public and private access to domain knowledge by designers, and the relation between imitative behaviour and innovation. A number of factors in a social system are identified that contribute to the emergence of phenomena that are normally associated to creativity and innovation in design. At the individual level the role of differences of abilities, persistence, opportunities, imitative behaviour, peer influence, and design strategies are discussed. At the field level determinants under inspection include group structure, social mobility and organisation, emergence of opinion leaders, established rules and norms, and distribution of adoption and quality assessments. Lastly, domain aspects that influence the interaction between designers and their social groups include the generation and access to knowledge, activities of gatekeeping, domain size and distribution, and artefact structure and representation. These insights are discussed in view of current findings and relevant modelling approaches in the literature. Whilst a number of assumptions and results are validated, others contribute to ongoing debates and suggest specific mechanisms and parameters for future experimentation. The thesis concludes by characterising this approach to the study of creativity in design as an alternative �in silico� method of inquiry that enables simulation with phenomena not amenable to direct manipulation. Lines of development for future work are advanced which promise to contribute to the experimental study of the social dimensions of design.

Este trabalho encontra-se situado na área de Inteligência Artificial, mais especificamente na modelagem de Sistemas Multiagentes destinados à simulação social. A área de pesquisa de simulação social baseada em agentes é uma área recente e bastante promissora. Por tratar de problemas extremamente complexos, existe a necessidade de criar modelos e abstrações para possibilitar sua realização. Dando continuidade a trabalhos anteriores, esta tese pretende consolidar uma nova versão do modelo MAS-SOC, destinado à definição de simulações sociais baseada em Sistemas Multiagentes Situados, com organizações que funcionam em ambientes determinados (organizações situadas). É proposta uma abordagem integrada, que conecta de maneira forte as entidades agentes, organizações e ambiente, sendo os agentes, o ambiente e as estruturas da organização tratadas como entidades de primeira ordem. A definição do ambiente é feita através da linguagem ELMS, estendida com uma infraestrutura normativa. Esta infraestrutura normativa é composta basicamente por objetos normativos e espaços normativos que permitem a distribuição espacial da informação normativa no ambiente, possibilitando a contextualização das normas que os agentes devem seguir em um escopo espacial determinado. A contextualização das normas facilita a sua operacionalização e a verificação de conformidade, reduzindo também a possibilidade de interpretações errôneas das normas. Com isso, a infraestrutura normativa conecta ambiente físico à estrutura da organização do sistema multiagente. Além disso, o modelo proposto usa um esquema mínimo de definição das organizações para armazenar informações e restrições que o projetista da simulação prefira representar desta forma. Esta maneira integrada de modelar os sistemas multiagentes, associando a organização ao espaço em que a organização deve funcionar, pode facilitar a modelagem de grandes sistemas, pois o conceito de espaço normativo permite que a modelagem seja feita através da partição do ambiente físico em módulos onde as atividades da organização situada são realizadas. Assim, o modelo trata de forma bastante prática o uso das normas organizacionais que podem ser representadas através de objetos normativos. Esta forma de representação possibilita aos agentes decidirem sobre a aderência as normas, já que estas não estão embutidas no mecanismo de raciocínio dos agentes. Além disso, a forma contextualizada das normas facilita raciocínio sobre elas e possibilita a aderência a normas previamente desconhecidas pelos agentes. / This work is situated in the research area of Artificial Intelligence, specifically the modelling of Multi-agent systems for social simulation. The research area of agent based social simulation is a recent and interesting area. In order to handle with its very complex problems, it requires the development of models and abstractions to make possible its realisation. Continuing previous works, this thesis aims to consolidate extensions to the MAS-SOC model, in order to turn it into a suitable model for the social simulation based on situated multi-agent systems with organizations that operate in determined environments (situated organisations). It is proposed an integrated approach in which multiagent entities such as agents, organisations and environments are strongly connected to each other, and the environment and the organisational structures being treated as first order entities. The definition of the environment is made with the use of the ELMS language, which have been extended with a normative infrastructure. The normative infrastructure is composed essentially by normative objects and normative places, which are means for the spatial distribution of the normative information over the environment, allowing the contextualisation of the norms in a bounded spatial scope. The norms being bounded in a specific spatial scope facilitates its operationalisation and conformity checks, also reducing the possibilities of norms misinterpretations. Thus, the normative infrastructure connects the physical environment to the organisational structures of the multiagent system. The thesis proposes that this integrated approach to model multi-agent systems may ease the modelling of large scale systems, since it allows the partition of the environment in a modular way, facilitating the operationalisation and verification of the adequacy of the structure of an organisation to the physical space where it is located, and also reducing the possibility of the misinterpretations of norms by the agents, through the contextualisation of norms. Also, the proposed scheme uses a minimal structure for the definition of the organisations in order to store information that the simulation designer prefers to represent in such way. Further, the proposed approach allows a very practical way to use of norms in a physical environment, by allowing the agents to reason about following a norm abiding behaviour or not, since the norms are not hard-wired in their reasoning mechanisms, and its contextualized form facilitates that agents reason about adhering to norms that were previously unknown to them.

Este trabalho encontra-se situado na área de Inteligência Artificial, mais especificamente na modelagem de Sistemas Multiagentes destinados à simulação social. A área de pesquisa de simulação social baseada em agentes é uma área recente e bastante promissora. Por tratar de problemas extremamente complexos, existe a necessidade de criar modelos e abstrações para possibilitar sua realização. Dando continuidade a trabalhos anteriores, esta tese pretende consolidar uma nova versão do modelo MAS-SOC, destinado à definição de simulações sociais baseada em Sistemas Multiagentes Situados, com organizações que funcionam em ambientes determinados (organizações situadas). É proposta uma abordagem integrada, que conecta de maneira forte as entidades agentes, organizações e ambiente, sendo os agentes, o ambiente e as estruturas da organização tratadas como entidades de primeira ordem. A definição do ambiente é feita através da linguagem ELMS, estendida com uma infraestrutura normativa. Esta infraestrutura normativa é composta basicamente por objetos normativos e espaços normativos que permitem a distribuição espacial da informação normativa no ambiente, possibilitando a contextualização das normas que os agentes devem seguir em um escopo espacial determinado. A contextualização das normas facilita a sua operacionalização e a verificação de conformidade, reduzindo também a possibilidade de interpretações errôneas das normas. Com isso, a infraestrutura normativa conecta ambiente físico à estrutura da organização do sistema multiagente. Além disso, o modelo proposto usa um esquema mínimo de definição das organizações para armazenar informações e restrições que o projetista da simulação prefira representar desta forma. Esta maneira integrada de modelar os sistemas multiagentes, associando a organização ao espaço em que a organização deve funcionar, pode facilitar a modelagem de grandes sistemas, pois o conceito de espaço normativo permite que a modelagem seja feita através da partição do ambiente físico em módulos onde as atividades da organização situada são realizadas. Assim, o modelo trata de forma bastante prática o uso das normas organizacionais que podem ser representadas através de objetos normativos. Esta forma de representação possibilita aos agentes decidirem sobre a aderência as normas, já que estas não estão embutidas no mecanismo de raciocínio dos agentes. Além disso, a forma contextualizada das normas facilita raciocínio sobre elas e possibilita a aderência a normas previamente desconhecidas pelos agentes. / This work is situated in the research area of Artificial Intelligence, specifically the modelling of Multi-agent systems for social simulation. The research area of agent based social simulation is a recent and interesting area. In order to handle with its very complex problems, it requires the development of models and abstractions to make possible its realisation. Continuing previous works, this thesis aims to consolidate extensions to the MAS-SOC model, in order to turn it into a suitable model for the social simulation based on situated multi-agent systems with organizations that operate in determined environments (situated organisations). It is proposed an integrated approach in which multiagent entities such as agents, organisations and environments are strongly connected to each other, and the environment and the organisational structures being treated as first order entities. The definition of the environment is made with the use of the ELMS language, which have been extended with a normative infrastructure. The normative infrastructure is composed essentially by normative objects and normative places, which are means for the spatial distribution of the normative information over the environment, allowing the contextualisation of the norms in a bounded spatial scope. The norms being bounded in a specific spatial scope facilitates its operationalisation and conformity checks, also reducing the possibilities of norms misinterpretations. Thus, the normative infrastructure connects the physical environment to the organisational structures of the multiagent system. The thesis proposes that this integrated approach to model multi-agent systems may ease the modelling of large scale systems, since it allows the partition of the environment in a modular way, facilitating the operationalisation and verification of the adequacy of the structure of an organisation to the physical space where it is located, and also reducing the possibility of the misinterpretations of norms by the agents, through the contextualisation of norms. Also, the proposed scheme uses a minimal structure for the definition of the organisations in order to store information that the simulation designer prefers to represent in such way. Further, the proposed approach allows a very practical way to use of norms in a physical environment, by allowing the agents to reason about following a norm abiding behaviour or not, since the norms are not hard-wired in their reasoning mechanisms, and its contextualized form facilitates that agents reason about adhering to norms that were previously unknown to them.

Este trabalho encontra-se situado na área de Inteligência Artificial, mais especificamente na modelagem de Sistemas Multiagentes destinados à simulação social. A área de pesquisa de simulação social baseada em agentes é uma área recente e bastante promissora. Por tratar de problemas extremamente complexos, existe a necessidade de criar modelos e abstrações para possibilitar sua realização. Dando continuidade a trabalhos anteriores, esta tese pretende consolidar uma nova versão do modelo MAS-SOC, destinado à definição de simulações sociais baseada em Sistemas Multiagentes Situados, com organizações que funcionam em ambientes determinados (organizações situadas). É proposta uma abordagem integrada, que conecta de maneira forte as entidades agentes, organizações e ambiente, sendo os agentes, o ambiente e as estruturas da organização tratadas como entidades de primeira ordem. A definição do ambiente é feita através da linguagem ELMS, estendida com uma infraestrutura normativa. Esta infraestrutura normativa é composta basicamente por objetos normativos e espaços normativos que permitem a distribuição espacial da informação normativa no ambiente, possibilitando a contextualização das normas que os agentes devem seguir em um escopo espacial determinado. A contextualização das normas facilita a sua operacionalização e a verificação de conformidade, reduzindo também a possibilidade de interpretações errôneas das normas. Com isso, a infraestrutura normativa conecta ambiente físico à estrutura da organização do sistema multiagente. Além disso, o modelo proposto usa um esquema mínimo de definição das organizações para armazenar informações e restrições que o projetista da simulação prefira representar desta forma. Esta maneira integrada de modelar os sistemas multiagentes, associando a organização ao espaço em que a organização deve funcionar, pode facilitar a modelagem de grandes sistemas, pois o conceito de espaço normativo permite que a modelagem seja feita através da partição do ambiente físico em módulos onde as atividades da organização situada são realizadas. Assim, o modelo trata de forma bastante prática o uso das normas organizacionais que podem ser representadas através de objetos normativos. Esta forma de representação possibilita aos agentes decidirem sobre a aderência as normas, já que estas não estão embutidas no mecanismo de raciocínio dos agentes. Além disso, a forma contextualizada das normas facilita raciocínio sobre elas e possibilita a aderência a normas previamente desconhecidas pelos agentes. / This work is situated in the research area of Artificial Intelligence, specifically the modelling of Multi-agent systems for social simulation. The research area of agent based social simulation is a recent and interesting area. In order to handle with its very complex problems, it requires the development of models and abstractions to make possible its realisation. Continuing previous works, this thesis aims to consolidate extensions to the MAS-SOC model, in order to turn it into a suitable model for the social simulation based on situated multi-agent systems with organizations that operate in determined environments (situated organisations). It is proposed an integrated approach in which multiagent entities such as agents, organisations and environments are strongly connected to each other, and the environment and the organisational structures being treated as first order entities. The definition of the environment is made with the use of the ELMS language, which have been extended with a normative infrastructure. The normative infrastructure is composed essentially by normative objects and normative places, which are means for the spatial distribution of the normative information over the environment, allowing the contextualisation of the norms in a bounded spatial scope. The norms being bounded in a specific spatial scope facilitates its operationalisation and conformity checks, also reducing the possibilities of norms misinterpretations. Thus, the normative infrastructure connects the physical environment to the organisational structures of the multiagent system. The thesis proposes that this integrated approach to model multi-agent systems may ease the modelling of large scale systems, since it allows the partition of the environment in a modular way, facilitating the operationalisation and verification of the adequacy of the structure of an organisation to the physical space where it is located, and also reducing the possibility of the misinterpretations of norms by the agents, through the contextualisation of norms. Also, the proposed scheme uses a minimal structure for the definition of the organisations in order to store information that the simulation designer prefers to represent in such way. Further, the proposed approach allows a very practical way to use of norms in a physical environment, by allowing the agents to reason about following a norm abiding behaviour or not, since the norms are not hard-wired in their reasoning mechanisms, and its contextualized form facilitates that agents reason about adhering to norms that were previously unknown to them.

Nous étudions dans cette thèse l'élaboration subjective de la satisfaction et l'impact de l'organisation du travail sur celle-ci. Nous traitons successivement le problème de la modélisation des processus psychologiques de la satisfaction, définie comme une attitude au travail, et celui de la modélisation de l'impact de l'organisation sur l'activité de travail. Nous nous inscrivons dans une démarche de modélisation sociale inédite dans l'étude de la satisfaction au travail: nous nous proposons de partir des théories et modèles en psychologie du travail et économie du bonheur pour représenter dans un modèle multi-agents les processus cognitifs qui amènent les individus à évaluer leur travail comme satisfaisant ou insatisfaisant. L'objectif est de fournir un modèle crédible de satisfaction qui permet de mieux comprendre l'impact de l'organisation du travail sur la satisfaction de ses employés. Pour ce faire nous avons confronté notre modèle à un scénario idéal de politique d'amélioration des conditions de travail initialisées sur des données réelles. Cette analyse a révélé que l'amélioration des conditions de travail ne conduit pas systématiquement à l'augmentation de la satisfaction: les profils cognitifs, qui représentent les manières typiques d'évaluer son attitude au travail, ont un impact considérable sur les conséquences de la politique. Dans un second temps nous avons appliqué notre modèle à un scénario d'évolution des conditions de travail représentant des données de panel. Nous avons été capables de reproduire en simulation les niveaux de satisfaction déclarée des individus à 9 et 7 mois d'intervalle. Par ailleurs, afin de proposer une représentation plus réaliste des scénarii de changement des conditions de travail, nous avons également développé un modèle d'activité en organisation. Nous avons d'abord analysé l'impact de diverses organisations du travail sur les performances des organisations, puis nous avons conduit une analyse de l'impact de l'activité en organisation sur la formation d'épisodes d'épuisement professionnel. Cette dernière étude a permis de faire apparaître l'importance de l'activité de travail sur le vécu des travailleurs; l'objectif étant de proposer à terme un modèle couplé d'activité et de satisfaction au travail. / We study in this thesis the subjective formation of job satisfaction and the impact of organization on employees satisfaction. First, we work on the modeling of psychological process of job satisfaction, defined as an attitude at work. Then, we propose a model to study the impact of work organization on work activity. Our research aims to study job satisfaction using an innovative methodological and theoretical approach in the domain of social simulation: based on major theories in the fields of organizational psychology and economy of well-being, our goal is to produce an agent-based model of the cognitive aspects of job satisfaction. Our purpose is to provide a theoretically as well as empirically grounded model of job satisfaction that fosters the understanding of organizational impact on employees' satisfaction. To do so, we tested our model on an ideal scenario of work conditions improvement policy. The results revealed that this policy do not systematically causes a global improvement on job satisfaction: agent's cognitive profil, that is a typical way to evaluate job satisfaction, have a great impact on policy outcomes. Next, we tested our model using a scenario based on a panel survey of work conditions conducted in a big french organization during 2013/14. We were able to reproduce declared individual levels of job satisfaction. Furthemore, in order to provide a more realistic representation of work improvement policy, we have also developed a work activity model. Firstly, we analyzed the impact of various work organizations on organizational performance, then we conducted an analysis of the impact of work activity on the formation of burnout episodes. This last study helped us to bring up the importance of work activity and organization on employees' well-being; the aim being eventually to propose a coupled model of work activity and job satisfaction.

The scientific consensus has for long been that residential segregation is best conceived of as a multidimensional phenomenon that can exist on several geographical scales (Massey & Denton, 1988; Lee et al., 2008; Reardon & O’Sullivan, 2004; Reardon et al., 2008). Despite this deepened understanding of residential segregation and how to best measure it, theoretical models of segregation processes have tended to disregard the diversity of dimensions and scales of segregation. Moreover, while residential segregation is broadly defined as the spatial separation of people of different social groups (Timberlake & Ignatov, 2014), the frequently used Schelling model is aspatial (Schelling, 1971). In contrast, the lesser-known Sakoda model incorporates a distance-decay effect and is thus explicitly spatial (Sakoda, 1971). The aim of this thesis was to evaluate two theoretical agent-based models of segregation processes—the Schelling- and Sakoda model—by measuring the segregation patterns they generate under different parameter settings across four dimensions and six spatial scales of segregation, ranging from the micro- to the macro-scale. Thus, providing an assessment of the capacity of these models to generate (grow) different forms of residential segregation. Results from simulation experiments showed that the popular Schelling model was limited in its capacity to generate different forms of segregation. In its standard configuration it could generate micro-segregation along two out of four dimensions: Evenness and Exposure. The spatially explicit Sakoda model was able to generate segregation patterns which varied substantially across all scales on the Evenness and Exposure dimensions. In addition, it was able to generate varied patterns of Concentration and Centralization under certain parameter settings. These findings contribute new insights to the possibilities afforded by these two models in modeling processes of residential segregation. If the goal for theoretical models is to generate segregation patterns which vary across all dimensions and scales of residential segregation, then the standard configuration of the Schelling model is not enough. This thesis suggest that the Sakoda model is a promising candidate for this purpose. In addition, this thesis shows the importance of using a comprehensive measurement framework in theoretical modeling of segregation processes.

Present-day Agent Based Modelling is used to simulate complex systems in which agents are explicitly heterogeneous. Researchers within the field of ABM have a set of tools at their disposal, yet little is known about the usability and learnability of these systems. Information Architecture establishes a set of guidelines for constructing digital spaces that facilitate the fulfilment of the user’s goal; these guidelines are expressed as Principles of Information Architecture and categories of user behaviour. The purpose of this paper is to determine the needs of ABM researchers and explore how scientific software can be improved to better support them in their work. A System Usability Scale questionnaire quantifies the current level of usability on ABM frameworks while semi-structured interviews with six expert modellers provide data on user needs and user behaviour. The participants are allowed to review more than one ABM framework by means of questionnaires and a cognitive walkthrough that exposes GUI elements and other framework features linked to procedural steps of modelling. Information Architecture principles are exposed in each interface along with user behaviour categories. Albeit limited in its scope of participants, the survey with in-depth interviews provides valuable information on the needs of domain experts. Data is analysed both quantitatively and qualitatively; the paper follows, therefore, a mixed-method approach. It is proven that, at the present moment, most ABM frameworks fail to meet established standards for usability and learnability. User needs are exposed through an analysis of the data reported by experts. Finally, considerations are presented upon the impact of implementing Information Architecture guidelines within ABM frameworks.

我們把經濟體視為一個複雜適應系統(complex adaptive system), 強調系統中異質性(heterogeneous)agent的學習適應行為與agent之間的互動性交互作用, 此時主流經濟學裡的分析架構, 如:代表性個人模型(represesentive agent model)、理性預期(rational expectation)、固定點均衡分析(fixed-point equilibrium analysis)等將不再適用, 取而代之的是演化經濟學(evolutionary economics)的研究典範, 這樣的研究架構下, 並沒有適當的數學分析工具可資運用, 因此我們改以agent-based建模(agent-based modelng)的社會模擬(social simulation)來建構一個人工的經濟體(artificial economy), 以此為主要研究方法, 這就是agent-based計算經濟學(agent-based computational economics)或稱人工經濟生命(artificial economic life)。 本文中以股票市場為主要的研究課題, 我們以遺傳規劃(genetic programming)的人工智慧(artificial intelligence)方法來模擬股市中有限理性(bounded rational)異質交易者的交易策略學習行為, 建構出一個人工股票市場(artificial stock market), 在這樣的架構下, 我們成功地產生出類似真實股票市場的股價時間序列特性, 我們同時也檢定了人工股票市場中價量的因果關係, 說明了在沒有外生因素之下, 人工股票市場的複雜系統可自發地產生出雙向的價量因果關係, 進一步地, 我們研究下層agent(交易者)行為與上層股價時間序列行為的關聯性, 我們也發現個體的行為並不能直接加總或推論出複雜適應系統的總體行為, 這就是突現性質(emergent property)的發生, 最後, 本文描述了agent-based計算經濟學研究架構的優勢與缺點, 再附帶介紹一個用以進行agent-based建模相關研究的軟體程式庫-SWARM。

This thesis sought to develop an agent-based model that replicates the formation of social and sexual partnerships in real-world settings with an eventual aim of revealing the main drivers of the HIV pandemic in a closed mixed society. Agent-based modelling is a computational modelling approach that allows for the simulation of the actions and interactions of autonomous agents, with the eventual objective of disovering global effects on the system. This modelling technique is less dependent on generalisations and does not average out the behaviour of individuals. Sexual partnerships formed in the model goes through the process of dating, courting and has a chance of developing into marriage as well as the possibility of breaking up or undergo divorce. Sexual partnership formation is based on a likeability index calculated using aspiration, attractiveness and age. Over and above the the sexual relationships we include commercial sex work. Commercial sex work depends mainly on the availability of female sex workers and their clients. We superimpose the spread of HIV on the social and sexual network model. Results from the model reveal that saturation of HIV prevalence is driven by the social and sexual network structure, behaviour change as well as biologic factors. Excluding commercial sex work in the model resulted in a decrease in HIV prevalence and incidence. Dense social networks resulted in a dense sexual network which consequently increased HIV incidence. A change in the infection probability per coital act contributed significantly to a change in incidence and prevalence levels. Model results also show that enrolling all HIV positive agents on antiretroviral therapy (ART) as from 2016 simulation year will help in curbing HIV transmission if zero dropout rate from ART is assumed. Therefore, on concomitant action to avoid dropouts from ART is necessary if full benefits of introducing ART to all HIV positive individuals are to be realised. / Operations Management / D.Phil. (Operations Research)