28 research outputs found

    Characterisation Theorems for Weighted Tree Automaton Models

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    In this thesis, we investigate different theoretical questions concerning weighted automata models over tree-like input structures. First, we study exact and approximated determinisation and then, we turn to Kleene-like and Büchi-like characterisations. We consider multiple weighted automata models, including weighted tree automata over semirings (Chapters 3 and 4), weighted forest automata over M-monoids (Chapter 5), and rational weighted tree languages with storage (Chapter 6). For an explanation as to why the last class can be considered as a weighted automaton model, we refer to page 188 of the thesis. We will now summarise the main contributions of the thesis. In Chapter 3, we focus on the determinisation of weighted tree automata and present our determinisation framework, called M-sequentialisation, which can model different notions of determinisation from the existing literature. Then, we provide a positive M-sequentialisation result for the case of additively idempotent semirings or finitely M-ambiguous weighted tree automata. Another important contribution of Chapter 3 is Theorem 77, where we provide a blueprint theorem that can be used to find determini- sation results for more classes of semirings and weighted tree automata easily. In fact, instead of repeating an entire determinisation construction, Theorem 77 allows us to prove a determinisation result by finding certain finite equivalence relations. This is a very potent tool for future research in the area of determinisation. In Chapter 4, we move from exact determinisation towards approximate determini- sation. We lift the formalisms and the main results from one approach from the literature from the word case to the tree case. This successfully results in an approximated determinisation construction for weighted tree automata over the tropical semiring. We provide a formal mathematical description of the approximated determinisation construction, rather than an algorithmic description as found in the related approach from the literature. In Chapter 5, we turn away from determinisation and instead consider Kleene-like and Büchi-like characterisations of weighted recognisability. We introduce weighted forest automata over M-monoids, which are a generalisation of weighted tree automata over M-monoids and weighted forest automata over semirings. Then, we prove that our recognisable weighted forest languages can be decomposed into a finite product of recognisable weighted tree languages. We also prove that the initial algebra semantic and the run semantic for weighted forest automata are equivalent under certain conditions. Lastly, we define rational forest expressions and forest M-expressions and and prove that the classes of languages generated by these formalisms coincide with recognisable weighted forest languages under certain conditions. In Chapter 6, we consider rational weighted tree languages with storage, where the storage is introduced by composing rational weighted tree languages without storage with a storage map. It has been proven in the literature that rational weighted tree languages with storage are closed under the rational operations. In Chapter 6, we provide alternative proofs of these closure properties. In fact, we prove that our way of introducing storage to rational weighted tree languages preserves the closure properties from rational weighted tree languages without storage.:1 Introduction 2 Preliminaries 2.1 Languages 2.2 WeightedLanguages 2.3 Weighted Tree Automata 3 A Unifying Framework for the Determinisation of Weighted Tree Automata 3.1 Introduction 3.2 Preliminaries 3.3 Factorisation in Monoids 3.3.1 Ordering Multisets over Monoids 3.3.2 Cayley Graph and Cayley Distance 3.3.3 Divisors and Rests 3.3.4 Factorisation Properties 3.4 Weighted Tree Automata over M_fin(M) and the Twinning Property 3.4.1 Weighted Tree Automata over M_fin(M) 3.4.2 The Twinning Property 3.5 Sequentialisation of Weighted Tree Automata over M_fin(M) 3.5.1 The Sequentialisation Construction 3.5.2 The Finitely R-Ambiguous Case 3.6 Relating WTA over M_fin(M) and WTA over S 3.7 M-Sequentialisation of Weighted Tree Automata 3.7.1 Accumulation of D_B 3.7.2 M-Sequentialisation Results 3.8 Comparison of our Results to the Literature 3.8.1 Determinisation of Unweighted Tree Automata 3.8.2 The Free Monoid Case 3.8.3 The Group Case 3.8.4 The Extremal Case 3.9 Conclusion 4 Approximated Determinisation of Weighted Tree Automata 125 4.1 Introduction 4.2 Preliminaries 4.3 Approximated Determinisation 4.3.1 The Approximated Determinisation Construction 4.3.2 Correctness of the Construction 4.4 The Approximated Twinning Property 4.4.1 Implications for Approximated Determinisability 4.4.2 Decidability of the Twinning Property 4.5 Conclusion 5 Kleene and Büchi Theorems for Weighted Forest Languages over M-Monoids 5.1 Introduction 5.2 Preliminaries 5.3 WeightedForestAutomata 5.3.1 Forests 5.3.2 WeightedForestAutomata 5.3.3 Rectangularity 5.3.4 I-recognisable is R-recognisable 5.4 Kleene’s Theorem 5.4.1 Kleene’s Theorem for Trees 5.4.2 Kleene’s Theorem for Forests 5.4.3 An Inductive Approach 5.5 Büchi’s Theorem 5.5.1 Büchi’s Theorem for Trees 5.5.2 Büchi’s Theorem for Forests 5.6 Conclusion 6 Rational Weighted Tree Languages with Storage 6.1 Introduction 6.2 Preliminaries 6.3 Rational Weighted Tree Languages with Storage 6.4 The Kleene-Goldstine Theorem 6.5 Closure of Rat(S¢,Σ,S) under Rational Operations 6.5.1 Top-Concatenation, Scalar Multiplication, and Sum 6.5.2 α-Concatenation 6.5.3 α-Kleene Star 6.6 Conclusion 7 Outlook Reference

    Weighted Tree Automata -- May it be a little more?

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    This is a book on weighted tree automata. We present the basic definitions and some of the important results in a coherent form with full proofs. The concept of weighted tree automata is part of Automata Theory and it touches the area of Universal Algebra. It originated from two sources: weighted string automata and finite-state tree automata

    Proposta de Framework Embasado em Algoritmo Genético para Otimização de Acordos de Compartilhamento de Infraestrutura para o 5G

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    Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2021.Com o avanço da tecnologia 5G no Brasil, espera-se que novos acordos de comparti-lhamento de infraestrutura surjam entre as operadoras de telefonia, incluindo-se modelos deparceira com entidades terceiras que ofereçam infraestrutura passiva. O compartilhamentotraz inúmeros benefícios, mas é um modelo complexo, que a médio e longo prazo pode gerarefeitos na competitividade do mercado em que se inserem. Neste sentido, esse trabalho pro-põe um framework de avaliação de acordos de compartilhamento embasado em algoritmogenético, que vai desde a etapa de dimensionamento de rede, passando pela otimização decustos entre os parceiros envolvidos, concluindo-se a análise com a avaliação dos efeitos de mercado trazidos pelo acordo ótimo. Constrói-se uma ferramenta em código aberto paraaplicação do framework, trazendo-se seus resultados para três tipos de cenários brasileiros:uma rede urbana densa, em São Paulo, uma rede urbana em Brasília, e uma rede rural em GoiásCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).With the advance of 5G in Brazil, new infrastructure sharing agreements are expected among operators, including partnership models with third party agents offering passive infrastructure. Infrastructure sharing is a beneficial agreements, however on the mid to long term might generate impacts in market competitivity where they are inserted. In this sense, this work proposes a framework for assessment of infrastructure sharing agreements, which begins at the radio network dimensioning phase, passing by the optimization of costs among partners, concluding the analysis at an evaluation of the effects of the optimal calculated deal on the market. A open- source tool for application of the framework is built, and its results are evaluated for three types of brazilian scenarios: a dense urban network, in São Paulo city, a urban network in Brasília, and a rural network in Goiás state

    Machine Learning for Optical Network Security Monitoring: A Practical Perspective

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    In order to accomplish cost-efficient management of complex optical communication networks, operators are seeking automation of network diagnosis and management by means of Machine Learning (ML). To support these objectives, new functions are needed to enable cognitive, autonomous management of optical network security. This paper focuses on the challenges related to the performance of ML-based approaches for detectionand localization of optical-layer attacks, and to their integration with standard Network Management Systems (NMSs). We propose a framework for cognitive security diagnostics that comprises an attack detection module with Supervised Learning (SL), Semi-Supervised Learning (SSL) and Unsupervised Learning (UL) approaches, and an attack localization module that deduces the location of a harmful connection and/or a breached link. The influence of false positives and false negatives is addressed by a newly proposed Window-based Attack Detection (WAD) approach. We provide practical implementation\ua0guidelines for the integration of the framework into the NMS and evaluate its performance in an experimental network testbed subjected to attacks, resulting with the largest optical-layer security experimental dataset reported to date

    The Largest Unethical Medical Experiment in Human History

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    This monograph describes the largest unethical medical experiment in human history: the implementation and operation of non-ionizing non-visible EMF radiation (hereafter called wireless radiation) infrastructure for communications, surveillance, weaponry, and other applications. It is unethical because it violates the key ethical medical experiment requirement for “informed consent” by the overwhelming majority of the participants. The monograph provides background on unethical medical research/experimentation, and frames the implementation of wireless radiation within that context. The monograph then identifies a wide spectrum of adverse effects of wireless radiation as reported in the premier biomedical literature for over seven decades. Even though many of these reported adverse effects are extremely severe, the true extent of their severity has been grossly underestimated. Most of the reported laboratory experiments that produced these effects are not reflective of the real-life environment in which wireless radiation operates. Many experiments do not include pulsing and modulation of the carrier signal, and most do not account for synergistic effects of other toxic stimuli acting in concert with the wireless radiation. These two additions greatly exacerbate the severity of the adverse effects from wireless radiation, and their neglect in current (and past) experimentation results in substantial under-estimation of the breadth and severity of adverse effects to be expected in a real-life situation. This lack of credible safety testing, combined with depriving the public of the opportunity to provide informed consent, contextualizes the wireless radiation infrastructure operation as an unethical medical experiment

    A QoS-Aware Joint Power and Subchannel Allocation Algorithm for Mobile Network Virtualization

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    Mobile network virtualization is a promising technology due to its flexibility and feasibility. Since it enables physical resources abstraction and sharing, the overall resource inefficiency can be reduced dramatically. By means of virtualization, mobile service providers can share their physical resources with multiple virtual network operators. In this paper, a joint power and subchannel allocation algorithm for mobile network virtualization (MNV) with quality of services support is proposed. It presents a resource allocation scheme for orthogonal frequency division multiple access-based MNV with multiple virtual network operators. An optimal solution is provided to maximize the total data rate of both infrastructure providers and virtual network operators. Numerical results have shown that the proposed resource allocation algorithm improves the overall performance

    An exploration of how agency and socio-cultural milieu support greater or lesser controlled gambling and recovery from gambling addiction

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    Most gamblers never experience addiction and the majority of those who do eventually recover. This thesis investigates how most maintain control over their gambling and how the majority of those who do experience gambling addiction regain control. Findings are based on 25 qualitative semi-structured interviews with participants who fit one of three ideal-type groups: (i) gamblers who have never experienced addiction; (ii) gamblers who have regained control after experience of gambling addiction; and (iii) gamblers experiencing addiction at time of interview. Participants were recruited who had never engaged in formal treatment because existing research suggests most who experience gambling addiction and/or recovery never to do so. This study is underpinned by a synthesis of Bourdieusian theory and Foucauldian-inspired governmentality literature which was used to guide the thesis and help explain gambling behaviour. Taking a Foucauldian genealogical approach, the dominant theory of addiction as a biomedical disorder is critiqued and revealed to be myth. Instead, (gambling) addiction is demonstrated to be a social construction which becomes embodied within individuals and thereby influences gambling behaviour. Consequentially, it is shown that research concerning substance use is applicable to the investigation of gambling behaviours. Given paucity of gambling research, substance-related literature is drawn upon throughout the thesis. Attention is given to research demonstrating regulation over drug use to be influenced by the social settings in which consumption takes place as well as the wider social and cultural milieus in which the lives of actors are embedded. Moreover, particular appreciation is given to literature indicating recovery from addiction to be supported by shifts in socio-cultural milieu. In contrast to most existing addictions/gambling research, the agential capacities of gamblers to shape their own behaviours, albeit in ways heavily constrained by context (or ‘structure’) are emphasised throughout the thesis. Data revealed various gambling-related strategies to help constrain gambling and minimise harm. These are examined and it is recommended that this knowledge could be used to aid development of more effective ‘harm-reduction’ style interventions and policies in ways which support less harmful patterns of gambling behaviour. However, although valuable, those with greater control tended to rely little on such strategies to manage their gambling. Instead, greater control over gambling and recovery from gambling addiction was found to have less to do with how participants gamble (e.g. whether or not they followed harm-reduction strategies) and far more to do with the wider, non-gambling-related, aspects of their lives and the nature of their subjectivities/dispositions. Principally influential were found to be the qualities of interviewees’ socio-cultural milieus. Alongside gambling, those with greater control tended to participate in non-gambling-related communities with attendant ways of thinking and cultural expectations (values/norms) that marginalise (heavier) gambling. Drawing on Bourdieusian and Foucauldian governmentality theory, it is argued that, because of their day-to-day participation in such communities/milieus, those with greater control embody mentalities and expectations which discourage riskier gambling behaviour. This, in turn, results in more ‘prudential’ subjectivities which discourage problematic gambling behaviour. Participants who had experienced recovery and many of those who had never experienced addiction revealed long-term reductions in gambling behaviour. Findings suggested these reductions (as well as recovery) to be supported by social and cultural processes, occurring over the life-course, which encourage increased participation in more ‘conventional’ life/milieus and thereby promote alterations in subjectivities in ways more conducive to control. A dual approach to discouraging problematic gambling behaviour is recommended. Although it is important to promote ‘safer’ ways of gambling (e.g. through promotion of harm-reduction style interventions and by designing gambling environments in ways to support greater constraint), it is also imperative to support the development of lives/milieus and subjectivities more conducive to control (e.g. participation in ‘conventional’ life and access to resources required to do so).Plymouth Drug and Alcohol Action Team (DAAT)Social Science Doctoral Training Centre (DTC), Plymouth Universit

    GALAXY: A new hybrid MOEA for the Optimal Design of Water Distribution Systems

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    This is the final version of the article. Available from American Geophysical Union via the DOI in this record.The first author would like to appreciate the financial support given by both the University of Exeter and the China Scholarship Council (CSC) toward the PhD research. We also appreciate the three anonymous reviewers, who help improve the quality of this paper substantially. The source code of the latest versions of NSGA-II and ε-MOEA can be downloaded from the official website of Kanpur Genetic Algorithms Laboratory via http://www.iitk.ac.in/kangal/codes.shtml. The description of each benchmark problem used in this paper, including the input file of EPANET and the associated best-known Pareto front, can be accessed from the following link to the Centre for Water Systems (http://tinyurl.com/cwsbenchmarks/). GALAXY can be accessed via http://tinyurl.com/cws-galaxy

    A weighted biobjective transformation technique for locating multiple optimal solutions of nonlinear equation systems

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    The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Due to the fact that a nonlinear equation system may contain multiple optimal solutions, solving nonlinear equation systems is one of the most important challenges in numerical computation. When applying evolutionary algorithms to solve nonlinear equation systems, two issues should be considered: i) how to transform a nonlinear equation system into a kind of optimization problem, and ii) how to develop an optimization algorithm to solve the transformed optimization problem. In this paper, we tackle the first issue by transforming a nonlinear equation system into a weighted biobjective optimization problem. By the above transformation, not only do all the optimal solutions of an original nonlinear equation system become the Pareto optimal solutions of the transformed biobjective optimization problem, but also their images are different points on a linear Pareto front in the objective space. In addition, we suggest an adaptive multiobjective differential evolution, the goal of which is to effectively locate the Pareto optimal solutions of the transformed biobjective optimization problem. Once these solutions are found, the optimal solutions of the original nonlinear equation system can also be obtained correspondingly. By combining the weighted biobjective transformation technique with the adaptive multiobjective differential evolution, we propose a generic framework for the simultaneous locating of multiple optimal solutions of nonlinear equation systems. Comprehensive experiments on 38 nonlinear equation systems with various features have demonstrated that our framework provides very competitive overall performance compared with several state-of-the-art methods

    Expert-in-the-Loop Multilateral Telerobotics for Haptics-Enabled Motor Function and Skills Development

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    Among medical robotics applications are Robotics-Assisted Mirror Rehabilitation Therapy (RAMRT) and Minimally-Invasive Surgical Training (RAMIST) that extensively rely on motor function development. Haptics-enabled expert-in-the-loop motor function development for such applications is made possible through multilateral telerobotic frameworks. While several studies have validated the benefits of haptic interaction with an expert in motor learning, contradictory results have also been reported. This emphasizes the need for further in-depth studies on the nature of human motor learning through haptic guidance and interaction. The objective of this study was to design and evaluate expert-in-the-loop multilateral telerobotic frameworks with stable and human-safe control loops that enable adaptive “hand-over-hand” haptic guidance for RAMRT and RAMIST. The first prerequisite for such frameworks is active involvement of the patient or trainee, which requires the closed-loop system to remain stable in the presence of an adaptable time-varying dominance factor. To this end, a wave-variable controller is proposed in this study for conventional trilateral teleoperation systems such that system stability is guaranteed in the presence of a time-varying dominance factor and communication delay. Similar to other wave-variable approaches, the controller is initially developed for the Velocity-force Domain (VD) based on the well-known passivity assumption on the human arm in VD. The controller can be applied straightforwardly to the Position-force Domain (PD), eliminating position-error accumulation and position drift, provided that passivity of the human arm in PD is addressed. However, the latter has been ignored in the literature. Therefore, in this study, passivity of the human arm in PD is investigated using mathematical analysis, experimentation as well as user studies involving 12 participants and 48 trials. The results, in conjunction with the proposed wave-variables, can be used to guarantee closed-loop PD stability of the supervised trilateral teleoperation system in its classical format. The classic dual-user teleoperation architecture does not, however, fully satisfy the requirements for properly imparting motor function (skills) in RAMRT (RAMIST). Consequently, the next part of this study focuses on designing novel supervised trilateral frameworks for providing motor learning in RAMRT and RAMIST, each customized according to the requirements of the application. The framework proposed for RAMRT includes the following features: a) therapist-in-the-loop mirror therapy; b) haptic feedback to the therapist from the patient side; c) assist-as-needed therapy realized through an adaptive Guidance Virtual Fixture (GVF); and d) real-time task-independent and patient-specific motor-function assessment. Closed-loop stability of the proposed framework is investigated using a combination of the Circle Criterion and the Small-Gain Theorem. The stability analysis addresses the instabilities caused by: a) communication delays between the therapist and the patient, facilitating haptics-enabled tele- or in-home rehabilitation; and b) the integration of the time-varying nonlinear GVF element into the delayed system. The platform is experimentally evaluated on a trilateral rehabilitation setup consisting of two Quanser rehabilitation robots and one Quanser HD2 robot. The framework proposed for RAMIST includes the following features: a) haptics-enabled expert-in-the-loop surgical training; b) adaptive expertise-oriented training, realized through a Fuzzy Interface System, which actively engages the trainees while providing them with appropriate skills-oriented levels of training; and c) task-independent skills assessment. Closed-loop stability of the architecture is analyzed using the Circle Criterion in the presence and absence of haptic feedback of tool-tissue interactions. In addition to the time-varying elements of the system, the stability analysis approach also addresses communication delays, facilitating tele-surgical training. The platform is implemented on a dual-console surgical setup consisting of the classic da Vinci surgical system (Intuitive Surgical, Inc., Sunnyvale, CA), integrated with the da Vinci Research Kit (dVRK) motor controllers, and the dV-Trainer master console (Mimic Technology Inc., Seattle, WA). In order to save on the expert\u27s (therapist\u27s) time, dual-console architectures can also be expanded to accommodate simultaneous training (rehabilitation) for multiple trainees (patients). As the first step in doing this, the last part of this thesis focuses on the development of a multi-master/single-slave telerobotic framework, along with controller design and closed-loop stability analysis in the presence of communication delays. Various parts of this study are supported with a number of experimental implementations and evaluations. The outcomes of this research include multilateral telerobotic testbeds for further studies on the nature of human motor learning and retention through haptic guidance and interaction. They also enable investigation of the impact of communication time delays on supervised haptics-enabled motor function improvement through tele-rehabilitation and mentoring
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