41 research outputs found

    Active Learning of Deterministic Timed Automata with Myhill-Nerode Style Characterization

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    We present an algorithm to learn a deterministic timed automaton (DTA) via membership and equivalence queries. Our algorithm is an extension of the L* algorithm with a Myhill-Nerode style characterization of recognizable timed languages, which is the class of timed languages recognizable by DTAs. We first characterize the recognizable timed languages with a Nerode-style congruence. Using it, we give an algorithm with a smart teacher answering symbolic membership queries in addition to membership and equivalence queries. With a symbolic membership query, one can ask the membership of a certain set of timed words at one time. We prove that for any recognizable timed language, our learning algorithm returns a DTA recognizing it. We show how to answer a symbolic membership query with finitely many membership queries. We also show that our learning algorithm requires a polynomial number of queries with a smart teacher and an exponential number of queries with a normal teacher. We applied our algorithm to various benchmarks and confirmed its effectiveness with a normal teacher

    Tools and Algorithms for the Construction and Analysis of Systems

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    This open access book constitutes the proceedings of the 28th International Conference on Tools and Algorithms for the Construction and Analysis of Systems, TACAS 2022, which was held during April 2-7, 2022, in Munich, Germany, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2022. The 46 full papers and 4 short papers presented in this volume were carefully reviewed and selected from 159 submissions. The proceedings also contain 16 tool papers of the affiliated competition SV-Comp and 1 paper consisting of the competition report. TACAS is a forum for researchers, developers, and users interested in rigorously based tools and algorithms for the construction and analysis of systems. The conference aims to bridge the gaps between different communities with this common interest and to support them in their quest to improve the utility, reliability, exibility, and efficiency of tools and algorithms for building computer-controlled systems

    Tools and Algorithms for the Construction and Analysis of Systems

    Get PDF
    This open access book constitutes the proceedings of the 28th International Conference on Tools and Algorithms for the Construction and Analysis of Systems, TACAS 2022, which was held during April 2-7, 2022, in Munich, Germany, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2022. The 46 full papers and 4 short papers presented in this volume were carefully reviewed and selected from 159 submissions. The proceedings also contain 16 tool papers of the affiliated competition SV-Comp and 1 paper consisting of the competition report. TACAS is a forum for researchers, developers, and users interested in rigorously based tools and algorithms for the construction and analysis of systems. The conference aims to bridge the gaps between different communities with this common interest and to support them in their quest to improve the utility, reliability, exibility, and efficiency of tools and algorithms for building computer-controlled systems

    Automated Deduction – CADE 28

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    This open access book constitutes the proceeding of the 28th International Conference on Automated Deduction, CADE 28, held virtually in July 2021. The 29 full papers and 7 system descriptions presented together with 2 invited papers were carefully reviewed and selected from 76 submissions. CADE is the major forum for the presentation of research in all aspects of automated deduction, including foundations, applications, implementations, and practical experience. The papers are organized in the following topics: Logical foundations; theory and principles; implementation and application; ATP and AI; and system descriptions

    Cost-effectiveness analysis of radiofrequency ablation versus drugs for the treatment of a trial fibrillation in the South African population

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    Thesis (PhD)--Stellenbosch University, 2021.ENGLISH SUMMARY : Atrial fibrillation is the most commonly found and sustained arrhythmia. It affects about 1% of the total population and is found in more than one in ten in the elderly. The prevalence is increasing with the aging population. Patients with atrial fibrillation are at an increased risk of heart failure and all-cause mortality, and have a fivefold increased risk of stroke. Atrial fibrillation is associated with debilitating symptoms and an impaired quality of life. The restoration and maintenance of sinus rhythm is favourable and the current guidelines recommend the use of both rate and rhythm control strategies, which involve the prescription of anti-arrhythmic drug therapy. These anti-arrhythmic drugs are frequently ineffective, with large studies showing that atrial fibrillation returns in as many as 85% of patients within one year. These drugs are also associated with adverse events, occasionally serious, which may lead to hospitalisation. Catheter ablation (a minimally invasive procedure), has over the past decade revolutionised the treatment of atrial fibrillation. The 2010 European Society of Cardiology guidelines recommend catheter ablation for paroxysmal atrial fibrillation as a class IIa recommendation with level of evidence “A”. Current literature indicates that patients with atrial fibrillation who undergo pulmonary vein ablation have a significantly lower risk of death, stroke and dementia compared to patients with atrial fibrillation who are not treated with ablation, while stroke and dementia is similar to that of the general population. This study used a decision tree analysis, a Markov model and Monte Carlo simulation to calculate the cost-effectiveness of catheter ablation versus commonly used anti-arrhythmic drugs for the treatment of paroxysmal atrial fibrillation. Input into the model was founded on an extensive literature review, interviews with local electrophysiologists and a sample of real patient data, which examined the costs associated with among others, the length of hospital stay and the cost of the procedure. The model simulated 1 000 patients receiving either pulmonary vein isolation through radiofrequency ablation or anti-arrhythmic drugs and the following variables were measured, QALYs, average cost, incremental costs, average effectiveness, incremental effectiveness, average length of stay in hospital for complications, relative risk of death for radiofrequency catheter ablation versus anti-arrhythmic drugs and also the net monetary benefits. A total of fourteen variables were tested and sensitivity analyses were performed on each. It was found that in all but two cases, pulmonary vein isolation with radiofrequency catheter ablation dominated over anti-arrhythmic drug therapy as being more cost-effective for the management of paroxysmal atrial fibrillation. Finally, it was determined that pulmonary vein isolation with radiofrequency catheter ablation should be considered as a first line therapy for patients with paroxysmal atrial fibrillation in South Africa.AFRIKAANSE OPSOMMING : Atriale fibrillasie is die mees algemene en volgehoue aritmie. Dit raak ongeveer 1% van die bevolking. Onder bejaardes is die voorkoms egter soveel as 10%, wat beteken dat die toestand toeneem in verhouding met die verouderende bevolking. Atriale fibrillasie verhoog ’n pasiënt se risiko vir beroerte vyfvoudig, tesame met hartversaking en alle-oorsake mortaliteit. Die toestand se uitmergelende simptome verlaag ook lewenskwaliteit. Die kanse vir die herstel en instandhouding van sinusritme is positief. Bestaande riglyne beveel dus die gebruik van ritme- of spoed-beheer medikasie aan, wat beteken dat anti-aritmie medikasie voorgeskryf word. Dit is egter dikwels oneffektief en verskeie omvattende studies het bewys dat tot 85% van die pasiënte binne een jaar weer ‘n ritmestoornis ervaar. Hierdie middels word ook dikwels verbind met newe-effekte wat ernstig mag wees en tot hospitalisasie mag lei. Kateterablasie (’n minimaal-ingrypende prosedure) het oor die afgelope dekade die behandeling van atriale fibrillasie onherkenbaar verander. Vir pasiënte wat hoogs simptomaties, of paroksismaal, is ten spyte van optimale terapie, beveel die Europese Vereniging van Kardiologie se 2010 riglyne ablasie aan as ‘n klas IIa aanbeveling. Huidige literatuur dui op ‘n laer koers van sterftes, beroerte en demensie onder atriale fibrillasie pasiënte wat atriale fibrillasie ablasie ondergaan, in vergelyking met pasiënte wat met medikasie behandel word. Eersgenoemde het inteendeel dieselfde risikoprofiel as die algemene bevolking. Hierdie studie gebruik ’n keuse-boom analisemodel en ’n waarskynlikheid-Markov model met Monte Carlo-simulasie om die koste-effektiwiteit van kateterablasie met anti-aritmiese medikasie te vergelyk in die behandeling van pasiënte met paroksismale atriale fibrillasie. Die data wat in die model gebruik word, is gebaseer op ’n uitgebreide literatuurstudie, onderhoude met elektrofisioloë, en ’n steekproef van pasiëntdata, en ondersoek, onder andere, die duur van hopitaalverblyf en die koste verbonde aan die prosedure. Die studie maak gebruik van ’n simulasiemodel waar 1 000 pasiënte óf ablasie óf medikasie ontvang het. Die volgende veranderlikes is gemeet: QALYs, gemiddelde koste, toenemende koste, gemiddelde doeltreffendheid, toenemende doeltreffendheid, gemiddelde hospitaalverblyf tydens komplikasies, die relatiewe riskio van sterfte en monetêre voordele. Veertien veranderlikes is getoets en aan sensitiwiteitsanalises onderwerp. In dertien uit die viertien analises was kateterablasie meer koste-effektief as anti-aritmiese medikasie in die behandeling en bestuur van anti-aritmiese medikasie. Die studie kom dus tot die gevolgtrekking dat kateterablasie oorweeg moet word as voorkeurterapie vir pasiënte met paroksismale atriale fibrillasie in Suid-Afrika.Doctora

    Situating Open Data

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    Open data and its effects on society are always woven into infrastructural legacies, social relations, and the political economy. This raises questions about how our understanding and engagement with open data shifts when we focus on its situated use. To shed a light on these questions, Situating Open Data provides several empirical accounts of open data practices, the local implementation of global initiatives, and the development of new open data ecosystems. Drawing on case studies in different countries and contexts, the chapters demonstrate the practices and actors involved in open government data initiatives unfolding within different socio-political settings. The book proposes three recommendations for researchers, policy-makers and practitioners. First, beyond upskilling through data literacy programmes, open data initiatives should be specified through the kinds of data practices and effects they generate. Second, global visions of open data implementation require more studies of the resonances and tensions created in localised initiatives. And third, research into open data ecosystems requires more attention to the histories and legacies of information infrastructures and how these shape who benefits from open data flows. As such, this volume departs from the framing of data as a resource to be deployed. Instead, it proposes a prism of different data practices in different contexts through which to study the social relations, capacities, infrastructural histories and power structures affecting open data initiatives. It is hoped that the contributions collected in Situating Open Data will spark critical reflection about the way open data is locally practiced and implemented. The contributions should be of interest to open data researchers, advocates, and those in or advising government administrations designing and rolling out effective open data initiatives

    Covid-19: reinforcing the impact of Islamic banking through value-based intermediation

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    The novel Covid-19 pandemic has caused an unprecedented human crisis around the globe. The necessary actions implemented to contain the virus have sparked both economic and social downturn. It shows the fragility and unpreparedness of the economy to face such a pandemic. Significant weakening of economic conditions has escalated the pressure on households, businesses and financial markets. However, before the Covid-19 outbreak, Bank Negara Malaysia has taken a new initiative by introducing Value-Based Intermediation (VBI). VBI’s strategy opens up a new holistic layer for Islamic banks in providing the public at large with impactful and profitable services. This paper discusses VBI’s strategy and its potential application from the viewpoint of Sharīʽah. This paper also discusses Islamic banks' activities in implementing VBI as well as their response to the Covid-19 pandemic, based on qualitative inquiry. The paper concludes that VBI is a long journey that requires significant transformation of mindset among key stakeholders. As Covid-19 has adversely impacted communities in several ways, Islamic banks could empower communities through provision of financial solutions that create positive impact

    A Verified Packrat Parser Interpreter for Parsing Expression Grammars

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    Parsing expression grammars (PEGs) offer a natural opportunity for building verified parser interpreters based on higher-order parsing combinators. PEGs are expressive, unambiguous, and efficient to parse in a top-down recursive descent style. We use the rich type system of the PVS specification language and verification system to formalize the metatheory of PEGs and define a reference implementation of a recursive parser interpreter for PEGs. In order to ensure termination of parsing, we define a notion of a well-formed grammar. Rather than relying on an inductive definition of parsing, we use abstract syntax trees that represent the computational trace of the parser to provide an effective proof certificate for correct parsing and ensure that parsing properties including soundness and completeness are maintained. The correctness properties are embedded in the types of the operations so that the proofs can be easily constructed from local proof obligations. Building on the reference parser interpreter, we define a packrat parser interpreter as well as an extension that is capable of semantic interpretation. Both these parser interpreters are proved equivalent to the reference one. All of the parsers are executable. The proofs are formalized in mathematical terms so that similar parser interpreters can be defined in any specification language with a type system similar to PVS.Comment: 15 pages, 15 figures, Certified Proofs and Program

    Cultural Dynamics in a Globalized World

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    The book contains essays on current issues in arts and humanities in which peoples and cultures compete as well as collaborate in globalizing the world while maintaining their uniqueness as viewed from cross- and inter-disciplinary perspectives. The book covers areas such as literature, cultural studies, archaeology, philosophy, history, language studies, information and literacy studies, and area studies. Asia and the Pacific are the particular regions that the conference focuses on as they have become new centers of knowledge production in arts and humanities and, in the future, seem to be able to grow significantly as a major contributor of culture, science and arts to the globalized world. The book will help shed light on what arts and humanities scholars in Asia and the Pacific have done in terms of research and knowledge development, as well as the new frontiers of research that have been explored and opening up, which can connect the two regions with the rest of the globe

    Políticas de Copyright de Publicações Científicas em Repositórios Institucionais: O Caso do INESC TEC

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    A progressiva transformação das práticas científicas, impulsionada pelo desenvolvimento das novas Tecnologias de Informação e Comunicação (TIC), têm possibilitado aumentar o acesso à informação, caminhando gradualmente para uma abertura do ciclo de pesquisa. Isto permitirá resolver a longo prazo uma adversidade que se tem colocado aos investigadores, que passa pela existência de barreiras que limitam as condições de acesso, sejam estas geográficas ou financeiras. Apesar da produção científica ser dominada, maioritariamente, por grandes editoras comerciais, estando sujeita às regras por estas impostas, o Movimento do Acesso Aberto cuja primeira declaração pública, a Declaração de Budapeste (BOAI), é de 2002, vem propor alterações significativas que beneficiam os autores e os leitores. Este Movimento vem a ganhar importância em Portugal desde 2003, com a constituição do primeiro repositório institucional a nível nacional. Os repositórios institucionais surgiram como uma ferramenta de divulgação da produção científica de uma instituição, com o intuito de permitir abrir aos resultados da investigação, quer antes da publicação e do próprio processo de arbitragem (preprint), quer depois (postprint), e, consequentemente, aumentar a visibilidade do trabalho desenvolvido por um investigador e a respetiva instituição. O estudo apresentado, que passou por uma análise das políticas de copyright das publicações científicas mais relevantes do INESC TEC, permitiu não só perceber que as editoras adotam cada vez mais políticas que possibilitam o auto-arquivo das publicações em repositórios institucionais, como também que existe todo um trabalho de sensibilização a percorrer, não só para os investigadores, como para a instituição e toda a sociedade. A produção de um conjunto de recomendações, que passam pela implementação de uma política institucional que incentive o auto-arquivo das publicações desenvolvidas no âmbito institucional no repositório, serve como mote para uma maior valorização da produção científica do INESC TEC.The progressive transformation of scientific practices, driven by the development of new Information and Communication Technologies (ICT), which made it possible to increase access to information, gradually moving towards an opening of the research cycle. This opening makes it possible to resolve, in the long term, the adversity that has been placed on researchers, which involves the existence of barriers that limit access conditions, whether geographical or financial. Although large commercial publishers predominantly dominate scientific production and subject it to the rules imposed by them, the Open Access movement whose first public declaration, the Budapest Declaration (BOAI), was in 2002, proposes significant changes that benefit the authors and the readers. This Movement has gained importance in Portugal since 2003, with the constitution of the first institutional repository at the national level. Institutional repositories have emerged as a tool for disseminating the scientific production of an institution to open the results of the research, both before publication and the preprint process and postprint, increase the visibility of work done by an investigator and his or her institution. The present study, which underwent an analysis of the copyright policies of INESC TEC most relevant scientific publications, allowed not only to realize that publishers are increasingly adopting policies that make it possible to self-archive publications in institutional repositories, all the work of raising awareness, not only for researchers but also for the institution and the whole society. The production of a set of recommendations, which go through the implementation of an institutional policy that encourages the self-archiving of the publications developed in the institutional scope in the repository, serves as a motto for a greater appreciation of the scientific production of INESC TEC
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