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Alternative Automata-based Approaches to Probabilistic Model CheckingMüller, David 13 November 2019 (has links)
In this thesis we focus on new methods for probabilistic model checking (PMC) with linear temporal logic (LTL). The standard approach translates an LTL formula into a deterministic ω-automaton with a double-exponential blow up.
There are approaches for Markov chain analysis against LTL with exponential runtime, which motivates the search for non-deterministic automata with restricted forms of non-determinism that make them suitable for PMC. For MDPs, the approach via deterministic automata matches the double-exponential lower bound, but a practical application might benefit from approaches via non-deterministic automata.
We first investigate good-for-games (GFG) automata. In GFG automata one can resolve the non-determinism for a finite prefix without knowing the infinite suffix and still obtain an accepting run for an accepted word. We explain that GFG automata are well-suited for MDP analysis on a theoretic level, but our experiments show that GFG automata cannot compete with deterministic automata.
We have also researched another form of pseudo-determinism, namely unambiguity, where for every accepted word there is exactly one accepting run. We present a polynomial-time approach for PMC of Markov chains against specifications given by an unambiguous Büchi automaton (UBA). Its two key elements are the identification whether the induced probability is positive, and if so, the identification of a state set inducing probability 1.
Additionally, we examine the new symbolic Muller acceptance described in the Hanoi Omega Automata Format, which we call Emerson-Lei acceptance. It is a positive Boolean formula over unconditional fairness constraints. We present a construction of small deterministic automata using Emerson-Lei acceptance. Deciding, whether an MDP has a positive maximal probability to satisfy an Emerson-Lei acceptance, is NP-complete. This fact has triggered a DPLL-based algorithm for deciding positiveness.
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Computing Quantiles in Markov Reward ModelsUmmels, Michael, Baier, Christel January 2013 (has links)
Probabilistic model checking mainly concentrates on techniques for reasoning about the probabilities of certain path properties or expected values of certain random variables. For the quantitative system analysis, however, there is also another type of interesting performance measure, namely quantiles. A typical quantile query takes as input a lower probability bound p ∈ ]0,1] and a reachability property. The task is then to compute the minimal reward bound r such that with probability at least p the target set will be reached before the accumulated reward exceeds r. Quantiles are well-known from mathematical statistics, but to the best of our knowledge they have not been addressed by the model checking community so far.
In this paper, we study the complexity of quantile queries for until properties in discrete-time finite-state Markov decision processes with nonnegative rewards on states. We show that qualitative quantile queries can be evaluated in polynomial time and present an exponential algorithm for the evaluation of quantitative quantile queries. For the special case of Markov chains, we show that quantitative quantile queries can be evaluated in pseudo-polynomial time.
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Conception sûre et optimale de systèmes dynamiques critiques auto-adaptatifs soumis à des événements redoutés probabilistes / Safe and optimal design of dynamical, critical self-adaptive systems subject to probabilistic undesirable eventsSprauel, Jonathan 19 February 2016 (has links)
Cette étude s’inscrit dans le domaine de l’intelligence artificielle, plus précisément au croisement des deux domaines que sont la planification autonome en environnement probabiliste et la vérification formelle probabiliste. Dans ce contexte, elle pose la question de la maîtrise de la complexité face à l’intégration de nouvelles technologies dans les systèmes critiques : comment garantir que l’ajout d’une intelligence à un système, sous la forme d’une autonomie, ne se fasse pas au détriment de la sécurité ? Pour répondre à cette problématique, cette étude a pour enjeu de développer un processus outillé, permettant de concevoir des systèmes auto-adaptatifs critiques, ce qui met en œuvre à la fois des méthodes de modélisation formelle des connaissances d’ingénierie, ainsi que des algorithmes de planification sûre et optimale des décisions du système. / This study takes place in the broad field of Artificial Intelligence, specifically at the intersection of two domains : Automated Planning and Formal Verification in probabilistic environment. In this context, it raises the question of the integration of new technologies in critical systems, and the complexity it entails : How to ensure that adding intelligence to a system, in the form of autonomy, is not done at the expense of safety ? To address this issue, this study aims to develop a tool-supported process for designing critical, self-adaptive systems. Throughout this document, innovations are therefore proposed in methods of formal modeling and in algorithms for safe and optimal planning.
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Modélisation du carnet d’ordres, Applications Market Making / Limit order book modelling, Market Making ApplicationsLu, Xiaofei 04 October 2018 (has links)
Cette thèse aborde différents aspects de la modélisation de la microstructure du marché et des problèmes de Market Making, avec un accent particulier du point de vue du praticien. Le carnet d’ordres, au cœur du marché financier, est un système de files d’attente complexe à haute dimension. Nous souhaitons améliorer la connaissance du LOB pour la communauté de la recherche, proposer de nouvelles idées de modélisation et développer des applications pour les Market Makers. Nous remercions en particuler l’équipe Automated Market Making d’avoir fourni la base de données haute-fréquence de très bonne qualité et une grille de calculs puissante, sans laquelle ces recherches n’auraient pas été possible. Le Chapitre 1 présente la motivation de cette recherche et reprend les principaux résultats des différents travaux. Le Chapitre 2 se concentre entièrement sur le LOB et vise à proposer un nouveau modèle qui reproduit mieux certains faits stylisés. A travers cette recherche, non seulement nous confirmons l’influence des flux d’ordres historiques sur l’arrivée de nouveaux, mais un nouveau modèle est également fourni qui réplique beaucoup mieux la dynamique du LOB, notamment la volatilité réalisée en haute et basse fréquence. Dans le Chapitre 3, l’objectif est d’étudier les stratégies de Market Making dans un contexte plus réaliste. Cette recherche contribueà deux aspects : d’une part le nouveau modèle proposé est plus réaliste mais reste simple à appliquer pour la conception de stratégies, d’autre part la stratégie pratique de Market Making est beaucoup améliorée par rapport à une stratégie naive et est prometteuse pour l’application pratique. La prédiction à haute fréquence avec la méthode d’apprentissage profond est étudiée dans le Chapitre 4. De nombreux résultats de la prédiction en 1- étape et en plusieurs étapes ont retrouvé la non-linéarité, stationarité et universalité de la relation entre les indicateurs microstructure et le changement du prix, ainsi que la limitation de cette approche en pratique. / This thesis addresses different aspects around the market microstructure modelling and market making problems, with a special accent from the practitioner’s viewpoint. The limit order book (LOB), at the heart of financial market, is a complex continuous high-dimensional queueing system. We wish to improve the knowledge of LOB for the research community, propose new modelling ideas and develop concrete applications to the interest of Market Makers. We would like to specifically thank the Automated Market Making team for providing a large high frequency database of very high quality as well as a powerful computational grid, without whom these researches would not have been possible. The first chapter introduces the incentive of this research and resumes the main results of the different works. Chapter 2 fully focuses on the LOB and aims to propose a new model that better reproduces some stylized facts. Through this research, not only do we confirm the influence of historical order flows to the arrival of new ones, but a new model is also provided that captures much better the LOB dynamic, notably the realized volatility in high and low frequency. In chapter 3, the objective is to study Market Making strategies in a more realistic context. This research contributes in two aspects : from one hand the newly proposed model is more realistic but still simple enough to be applied for strategy design, on the other hand the practical Market Making strategy is of large improvement compared to the naive one and is promising for practical use. High-frequency prediction with deep learning method is studied in chapter 4. Many results of the 1-step and multi-step prediction have found the non-linearity, stationarity and universality of the relationship between microstructural indicators and price change, as well as the limitation of this approach in practice.
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Var kommer mina kläder ifrån? : En kvalitativ studie om hur uppfattningen och informationen om Country of Manufacture påverkar konsumenters köpbeslut / Where do my clothes come from? : A qualitative study of how the perception and information about Country of Manufacture affects consumers' purchasing decisionsCampoverde Morales, Melina, Khusnuddinova, Dilnoza January 2021 (has links)
Syfte: Denna studie syftar till att undersöka hur konsumenters köpbeslut påverkas utifrån deras kunskap och uppfattning om produkters tillverkningsland (Country of Manufacture). Metod: I denna studie används den kvalitativa forskningsmetoden där datainsamlingen utfördes genom 10 kvalitativa semistrukturerade intervjuer via telefonsamtal och Zoom-möten. Slutsatser: Informationen om ett tillverkningsland används i konsumenternas utvärdering av alternativ i form av stereotyper om länder, vilket även påverkar deras förväntningar av produktens inre värden. Påverkan av informationen om tillverkningslandet är större vid personliga och känslomässiga aspekter i form av fientlighet, affinitet och etnocentrism. Bakomliggande faktorerna till dessa aspekter är politik, hållbarhet och religion vilket uppstår på kollektiv och individuell nivå utifrån deras livssituation och tidigare erfarenheter. Dessutom tar konsumenten ställningstaganden över om de ska genomföra ett köp eller inte utifrån dessa aspekter. / Purpose: This study aims to investigate how consumers purchasing decisions are affected based on their knowledge and perception of the Country of Manufacture of products. Method: This study has a qualitative research method where collection of data was performed through 10 qualitative semi-structured interviews via telephone conversations and Zoom meetings. Conclusions: The information about a Country of Manufacture is used in consumers' evaluation of alternatives in the form of stereotypes about countries, which also affects their expectations of the product's intrinsic values. The influence of the information about the Country of Manufacture is greater in personal and emotional aspects in the form of animosity, affinity and ethnocentrism. The underlying factors to these aspects are politics, sustainability and religion, which arises on a collective and individual level based on their life situation and previous experiences. In addition, the consumer takes a stand on whether or not to make a purchase based on these aspects.
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REAL-TIME UPDATING AND NEAR-OPTIMAL ENERGY MANAGEMENT SYSTEM FOR MULTI-MODE ELECTRIFIED POWERTRAIN WITH REINFORCEMENT LEARNING CONTROLBiswas, Atriya January 2021 (has links)
Energy management systems (EMSs), implemented in the electronic control unit (ECU) of an actual vehicle with electri ed powertrain, is a much simpler version of the theoretically developed EMS. Such simpli cation is done to accommodate the EMS within the given memory constraint and computational capacity of the ECU. The simpli cation should ensure reasonable performance compared to theoretical EMS under real-life driving scenarios. The process of simpli cation must be effective to create a versatile and utilitarian EMS. The reinforcement learning-based controllers feature pro table characteristics in optimizing the performance of controllable physical systems as they do not mandatorily require a mathematical model of system dynamics (i.e. they are model-free). Quite naturally, it can aspired to testify such prowess of reinforcement learning-based controllers in achieving near-global optimal performance for energy management system (supervisory) of electri ed powertrains. Before deployment of any supervisory controller as a mainstream controller, they should be essentially scrutinized through various levels of virtual simulation platforms with an ascending order of physical system emulating-capability. The controller evolves from a mathematical concept to an utilitarian embedded system through a series of these levels where it undergoes gradual transformation to finally become apposite for a real physical system. Implementation of the control strategy in a Simulink-based forward simulation model could be the first stage of the aforementioned evolution process. This brief will delineate all the steps required for implementing an reinforcement learning-based supervisory controller in a forward simulation model of a hybrid electric vehicle. A novel framework of loss-minimization based instantaneous optimal strategy is introduced for the energy management system of a multi-mode hybrid electric powertrain in this brief. The loss-minimization strategy is flexible enough to be implemented in any architecture of electrified powertrains. It is mathematically proven that the overall system loss minimization is equivalent to the minimization of fuel consumption. An online simulation framework is developed in this article to evaluate the performance of a multi-mode electrified powertrain equipped with more than one power source. An electrically variable transmission with two planetary gear-set has been chosen as the centerpiece of the powertrain considering the versatility and future prospects of such transmissions. It is noteworthy to mention that a novel architecture topology selected for this dissertation is engendered through a series of rigorous screening process whose workflow is presented here with brevity.
One of the legitimate concern of multi-mode transmission is it's proclivity to contribute discontinuity of power-flow in the downstream of the powertrain. Mode-shift events can be predominantly held responsible for engendering such discontinuity. Advent of dynamic coordinated control as a technique for ameliorating such discontinuity has been substantiated by many scholars in literature. Hence, a system-level coordinated control is employed within the energy management system which governs the mode schedule of the multi-mode powertrain in real-time simulation. / Thesis / Doctor of Philosophy (PhD)
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AI – Can You Afford To Wait? / AI – Har du råd att vänta?Tersander, Jacob January 2018 (has links)
The paradigm of diffusion research can be traced back all the way to the 1940s when Ryan and Gross investigated the diffusion of hybrid seed among farmers in Iowa. Since the 1960s diffusion research has been applied in a wide variety of disciplines, for instance, to study the diffusion of the Internet and the non-diffusion of the Dvorak keyboard. Currently, the technologies that are on top of the Gartner Hype Cycle are all associated with Artificial Intelligence (AI), which shortly can be defined as learning devices that perceive their environment and take actions to maximize their success at some goal. Consequently, some people suggest that the current hype surrounding AI can be the end of the human kind, while others believe it will give way for millions of fresh jobs and cleverer decision-making. In recent years both media and political organizations have shown great interest in AI. In addition, the industry is captivated by the potential uses of AI. In the last years, AI-related companies in the US have raised billions of dollars in the stock market together with a large number of acquisitions. The large flow of capital into AI technology underpins the fast development of AI solutions. The purpose of this study is to investigate how groups approach AI. What can be concluded after reviewing different sectors is that organizations seem to share a common interest of AI. Furthermore, organizations share the opinion that eventually AI will be a more natural part of their processes. Organizations investing a larger share of their budget in R&D have a longer experience of using AI and are currently doing projects utilizing more advanced technologies within AI. In organizations from other sectors, the investments in AI depend on the people with the authority to invest money in projects and their view on AI. Organizations generally seem to approach AI in a similar way. Firstly, they evaluate what AI is. Secondly, they find areas to make small iterative PoC-projects utilizing AI, usually with machine learning. Finally, more money is invested if the PoC-projects were successful and the organization starts looking at how to acquire more competence within the area to fully exploit the value of AI. / Paradigmet för innovationsspridning kan spåras ända tillbaka till 1940-talet när Ryan och Gross undersökte spridningen av hybridfrön bland bönder i Iowa. Sedan 1960-talet har forskningen tillämpats inom en mängd olika discipliner, till exempel för att studera spridningen av Internet och icke-spridningen av Dvorak-tangentbordet. För närvarande är teknologierna som ligger på toppen av Gartner Hype-cykeln alla förknippade med artificiell intelligens (AI), som kan definieras som lärande enheter som uppfattar sin miljö och vidtar åtgärder för att maximera sin framgång gällande något mål. Hypen som nu finns kring AI har lett till att vissa människor tror att det kan innebära slutet för mänskligheten medan andra tror att det kommer att ge plats för miljoner nya jobb och smartare beslutsfattande. Under de senaste åren har både medier och politiska organisationer visat stort intresse för AI samt visat intresse för potentiella användningsområden av AI. AI-relaterade företag i USA har under de senaste åren har tagit in miljarder dollar i riskkapital. Ett stort antal förvärv och kapitalflödet till AI-teknik ökar den snabba utvecklingen av AI-lösningar. Syftet med denna studie är att beskriva spridningen av AI i organisationer från ett antal olika sektorer. Vad som kan sägas efter att ha studerat olika sektorer är att organisationer delar en gemensam nyfikenhet för AI och att de tror att AI kommer bli en allt mer naturlig del av sina processer. De företag som spenderar mycket pengar på FoU har längre erfarenhet av att använda AI och gör för närvarande projekt som använder mer avancerade tekniker. I andra organisationer är investeringarna inom AI beroende av de anställda som har rätt att investera pengar i projekt och deras syn på AI. Organisationer verkar allmänt närma sig AI på ett liknande sätt där de först utvärderar vad AI är. Därefter väljer de ett antal områden där de gör små iterativa projekt där de utnyttjar AI, vanligtvis via ML. Därefter investerades mer pengar om de små projekten lyckas och företaget börjar titta på hur man kan förvärva mer kompetens inom området.
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Scheduling in Wireless Networks with Limited and Imperfect Channel KnowledgeOuyang, Wenzhuo 18 August 2014 (has links)
No description available.
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Dynamic Routing for Fuel Optimization in Autonomous VehiclesRegatti, Jayanth Reddy 14 August 2018 (has links)
No description available.
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Conversions from Islam to Christianity in the SudanStraehler, Reinhold 30 November 2005 (has links)
This research project focuses on conversions from Islam to Christianity in the Sudan. It first
gives a biblical and theological understanding of conversion and then introduces the sociological
and psychological understanding of such a change in religious affiliation. It discusses conversion
as a spiritual decision process and develops a spiritual decision matrix for evaluating conversion processes of Muslims. The heart of the study is an analysis of the conversion processes of six converts with a Northern Sudanese background from different Muslim tribes. The interviews that were conducted with these converts are analysed in terms of five parameters: reasons for conversion; factors that led to conversion; stages in the conversion processes; problems encountered during the conversion processes; and results of the conversion. These parameters are compared with existing data from six studies of Muslims in other geographical areas who also converted to the Christian faith. / Christian Spirituality Church History and Missiology / M.Th. (Missiology)
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