Formal methods with a touch of magic

Machine learning and formal methods have complimentary benefits and drawbacks. In this work, we address the controller-design problem with a combination of techniques from both fields. The use of black-box neural networks in deep reinforcement learning (deep RL) poses a challenge for such a combination. Instead of reasoning formally about the output of deep RL, which we call the wizard, we extract from it a decision-tree based model, which we refer to as the magic book. Using the extracted model as an intermediary, we are able to handle problems that are infeasible for either deep RL or formal methods by themselves. First, we suggest, for the first time, a synthesis procedure that is based on a magic book. We synthesize a stand-alone correct-by-design controller that enjoys the favorable performance of RL. Second, we incorporate a magic book in a bounded model checking (BMC) procedure. BMC allows us to find numerous traces of the plant under the control of the wizard, which a user can use to increase the trustworthiness of the wizard and direct further training

Reading in the kindergarten

This study examines the effectiveness of implementing a formal reading program in the Kindergarten. Past and present reading instruction methods were reviewed. Benefits, as well as problems, associated with such implementation and instruction were discussed and conclusions were drawn from the literature. Guidelines and recommendations for implementing various approaches to the teaching of reading in the Kindergarten were outlined

Analysing accident reports using structured and formal methods

Formal methods are proposed as a means to improve accident reports, such as the report into the 1996 fire in the Channel Tunnel between the UK and France. The size and complexity of accident reports create difficulties for formal methods, which traditionally suffer from problems of scalability and poor readability. This thesis demonstrates that features of an engineering-style formal modelling process, particularly the structuring of activity and management of information, reduce the impact of these problems and improve the accuracy of formal models of accident reports. This thesis also contributes a detailed analysis of the methodological requirements for constructing accident report models. Structured, methodical construction and mathematical analysis of the models elicits significant problems in the content and argumentation of the reports. Once elicited, these problems can be addressed. This thesis demonstrates the benefits and limitations of taking a wider scope in the modelling process than is commonly adopted for formal accident analysis. We present a deontic action logic as a language for constructing models of accident reports. Deontic action models offer a novel view of the report, which highlights both the expected and actual behaviour in the report, and facilitates examination of the conflict between the two. This thesis contributes an objective analysis of the utility of both deontic and action logic operators to the application of modelling accident reports. A tool is also presented that executes a subset of the logic, including these deontic and action logic operators

Portuguese Experience With IFRS Adoption As Perceived By Auditors

Purpose: Drawing on the experience of adoption of a model based on the International Financial Reporting Standards (IFRS) by Portuguese non-financial unlisted companies in 2010, called Sistema de Normalização Contabilística (SNC), this paper explores auditors’ perceptions regarding dimensions of relevance and suitability of the new accounting model to the Portuguese setting, major problems encountered, and the main engendered benefits. Methodology: An interpretative approach based on qualitative research methods was adopted, in which sixteen interviews with statutory auditors were conducted from a vantage point in 2017, seven years after the formal implementation of the IFRS-based model. Findings: Evidence suggests enduring problems but mostly a significant level of legitimation and institutionalization of the IFRS-based model: (i) the perceived motivations for SNC adoption are a good fit with the theoretically acknowledged motivations underlying accounting convergence; (ii) the principle-based standards and the fair value were largely perceived favorably; and (iii) the IFRS-based model brought about a number of benefits as expected ex ante. Implications: Findings shed light on the potential of the IFRS model to conform to countries whose accounting systems are remarkably disparate – as it was in Portugal – and offer an agenda for regulators and local and international policymakers. Originality and value: This study contributes to the accounting literature on IFRS adoption by providing empirical evidence from a European country that posited an a priori adverse context.info:eu-repo/semantics/publishedVersio

Support Groups

When people experience traumas, crises, or catastrophes, when they encounter medical or interpersonal difficulties that they cannot cope with by themselves, or if they simply need to find a sympathetic audience who will listen to their problems, they often turn to support groups: groups of people who meet to exchange social support about a problem or situation that they all have experienced. Support groups, which are also known as self-help groups, exist for nearly every major medical, psychological, or stress-related problem. Each one is likely to be unique in some respects, but most such groups are practical in focus and interpersonal in method, for they usually strive to provide members with both emotional support and useful information. Support groups are usually organized and regulated by the members themselves, yet members often report benefits from participation that rival the gains of members of more formal and traditional treatment methods

A Comparison Of Delivery Formats To Encourage Student-Centered Learning In A Power Engineering Technology Course

This paper describes a student-centered approach to a power engineering technology course using the flipped or inverted classroom as well as active learning in the form of group discussions and team problem solving. The study compares student performance and perceptions of a traditional, teaching-centered classroom to two different flipped courses: one using video lectures and one using a media-enhanced electronic textbook. The authors compared courses in the areas of 1) student performance on multiple choice and numerical analysis problems, 2) students’ perceptions of course delivery format and satisfaction with the course and instructor, and 3) technical content coverage. Results show little difference in student achievement between the course formats, strong negative reactions by students to unfamiliar instructional methods, and little difference in content coverage. The authors believe that the outcomes of this study can be attributed to the benefits of small class sizes (n<12), which naturally enable active learning to be utilized without the need for rigid and formal course structure

Improving tracking of trajectories through tracking rate regulation: application to UAVs

The tracking problem (that is, how to follow a previously memorized path) is one of the most important problems in mobile robots. Several methods can be formulated depending on the way the robot state is related to the path. “Trajectory tracking” is the most common method, with the controller aiming to move the robot toward a moving target point, like in a real-time servosystem. In the case of complex systems or systems under perturbations or unmodeled effects, such as UAVs (Unmanned Aerial Vehicles), other tracking methods can offer additional benefits. In this paper, methods that consider the dynamics of the path’s descriptor parameter (which can be called “error adaptive tracking”) are contrasted with trajectory tracking. A formal description of tracking methods is first presented, showing that two types of error adaptive tracking can be used with the same controller in any system. Then, it is shown that the selection of an appropriate tracking rate improves error convergence and robustness for a UAV system, which is illustrated by simulation experiments. It is concluded that error adaptive tracking methods outperform trajectory tracking ones, producing a faster and more robust convergence tracking, while preserving, if required, the same tracking rate when convergence is achieved

Bayesian belief network model for the safety assessment of nuclear computer-based systems

The formalism of Bayesian Belief Networks (BBNs) is being increasingly applied to probabilistic modelling and decision problems in a widening variety of fields. This method provides the advantages of a formal probabilistic model, presented in an easily assimilated visual form, together with the ready availability of efficient computational methods and tools for exploring model consequences. Here we formulate one BBN model of a part of the safety assessment task for computer and software based nuclear systems important to safety. Our model is developed from the perspective of an independent safety assessor who is presented with the task of evaluating evidence from disparate sources: the requirement specification and verification documentation of the system licensee and of the system manufacturer; the previous reputation of the various participants in the design process; knowledge of commercial pressures;information about tools and resources used; and many other sources. Based on these multiple sources of evidence, the independent assessor is ultimately obliged to make a decision as to whether or not the system should be licensed for operation within a particular nuclear plant environment. Our BBN model is a contribution towards a formal model of this decision problem. We restrict attention to a part of this problem: the safety analysis of the Computer System Specification documentation. As with other BBN applications we see this modelling activity as having several potential benefits. It employs a rigorous formalism as a focus for examination, discussion, and criticism of arguments about safety. It obliges the modeller to be very explicit about assumptions concerning probabilistic dependencies, correlations, and causal relationships. It allows sensitivity analyses to be carried out. Ultimately we envisage this BBN, or some later development of it, forming part of a larger model, which might well take the form of a larger BBN model, covering all sources of evidence about pre-operational life-cycle stages. This could provide an integrated model of all aspects of the task of the independent assessor, leading up to the final judgement about system safety in a particular context. We expect to offer some results of this further work later in the DeVa project

Social prescribing for mental health and well-being: mechanisms of action, active ingredients, and barriers & enablers to effective engagement

Social prescribing involves the referral of individuals to community activities, often to support their mental health and well-being. There is growing evidence on the efficacy of social prescribing to improve mental health, however less is known about how these groups bring about beneficial effects, or about barriers or enablers facing referrers. I addressed three distinct but complementary objectives. In Study 1 I conducted a review of ‘mechanisms of action’ underlying the impact of leisure activities on health, producing a multi-level ‘theory of change’ framework. I found leisure activities act through biological, psychological, social and behavioural mechanisms, to produce mental and physical health benefits. In Study 2, I used ethnographic methods to explore how four social prescribing community groups produced mental health benefits for individuals, often with severe mental health problems. Shared active ingredients included excellent facilitator inter-personal skills, high regularity of activities, creation of a safe space, high affordability/accessibility, and shared lived experience of mental health problems. Shared mechanisms were increased purpose/meaning, experience of pleasure/joy, increased social support, increased structure/routine, formation of friendships and reduced loneliness, and enhanced sense of community and belonging. Study 3 used qualitative interviews to explore barriers and enablers for GPs in engaging with social prescribing for individuals with mental health problems, mapping them onto the Capability, Opportunity, Motivation-Behaviour (COM-B) change model. My findings highlighted the need for increased formal GP training on how to engage with social prescribing effectively, and the benefits of active inter-organisational partnerships and hand-holding opportunities to accompany individuals to initial sessions. My findings support the conceptualisation of social prescribing as a complex intervention. Social prescribing however is not a single, clearly defined intervention and different community groups/activities will involve different mechanisms and active ingredients. In its broadest sense social prescribing reflects a more salutogenic, personalised, biopsychosocial and less individualised approach towards mental health