Proof nets and the call-by-value λ-calculus

International audienceThis paper gives a detailed account of the relationship between (a variant of) the call-by-value lambda calculus and linear logic proof nets. The presentation is carefully tuned in order to realize an isomorphism between the two systems: every single rewriting step on the calculus maps to a single step on proof nets, and viceversa. In this way, we obtain an algebraic reformulation of proof nets. Moreover, we provide a simple correctness criterion for our proof nets, which employ boxes in an unusual way, and identify a subcalculus that is shown to be as expressive as the full calculus

Proceedings videojogos 2020

The 12th Edition of the International Conference on Videogame Sciences and Arts, Videojogos2020, is a joint organization of the School of Public Management, Communication and Tourism – Polytechnic Institute of Bragança (EsACT – IPB) and the Portuguese Society of Videogames Sciences (SPCV). This year, due to the pandemic context, activities were conducted online.info:eu-repo/semantics/publishedVersio

Linearity and Uniqueness: An Entente Cordiale

Substructural type systems are growing in popularity because they allow for a resourceful interpretation of data which can be used to rule out various software bugs. Indeed, substructurality is finally taking hold in modern programming; Haskell now has linear types roughly based on Girard’s linear logic but integrated via graded function arrows, Clean has uniqueness types designed to ensure that values have at most a single reference to them, and Rust has an intricate ownership system for guaranteeing memory safety. But despite this broad range of resourceful type systems, there is comparatively little understanding of their relative strengths and weaknesses or whether their underlying frameworks can be unified. There is often confusion about whether linearity and uniqueness are essentially the same, or are instead ‘dual’ to one another, or somewhere in between. This paper formalises the relationship between these two well-studied but rarely contrasted ideas, building on two distinct bodies of literature, showing that it is possible and advantageous to have both linear and unique types in the same type system. We study the guarantees of the resulting system and provide a practical implementation in the graded modal setting of the Granule language, adding a third kind of modality alongside coeffect and effect modalities. We then demonstrate via a benchmark that our implementation benefits from expected efficiency gains enabled by adding uniqueness to a language that already has a linear basis

Verifying safety and persistence in hybrid systems using flowpipes and continuous invariants

We describe a method for verifying the temporal property of persistence in non-linear hybrid systems. Given some system and an initial set of states, the method establishes that system trajectories always eventually evolve into some specified target subset of the states of one of the discrete modes of the system, and always remain within this target region. The method also computes a time-bound within which the target region is always reached. The approach combines flowpipe computation with deductive reasoning about invariants and is more general than each technique alone. We illustrate the method with a case study showing that potentially destructive stick-slip oscillations of an oil-well drill eventually die away for a certain choice of drill control parameters. The case study demonstrates how just using flowpipes or just reasoning about invariants alone can be insufficient and shows the richness of systems that one can handle with the proposed method, since the systems features modes with non-polynomial ODEs. We also propose an alternative method for proving persistence that relies solely on flowpipe computation

On the Verification of Parametric Systems

We present an approach to the verification of systems for whose description some elements - constants or functions - are underspecified and can be regarded as parameters, and, in particular, describe a method for automatically generating constraints on such parameters under which certain safety conditions are guaranteed to hold. We present an implementation and illustrate its use on several examples.Comment: 26 pages. arXiv admin note: text overlap with arXiv:1910.0520

Desenvolvimento de detetores para imagiologia baseados em MPGDs e suas aplicações

Doutoramento em FísicaEste trabalho descreve o desenvolvimento e aplicação de sistemas baseados em detetores gasosos microestruturados, para imagiologia de fluorescência de raios-X por dispersão em energia (EDXRF). A técnica de imagiologia por fluorescência de raios-X assume-se como uma técnica poderosa, não-destrutiva, em análises da distribuição espacial de elementos em materiais. Os sistemas para imagiologia de EDXRF desenvolvidos são constituídos por: um tubo de raios-X, usado para excitar os elementos da amostra; um detetor gasoso microestruturado; e uma lente pinhole que foca a radiação de fluorescência no plano do detetor formando assim a imagem e permitindo a sua ampliação. Por outro lado é estudada a influência do diâmetro da abertura do pinhole bem como do fator de ampliação obtido para a imagem, na resolução em posição do sistema. Foram usados dois conceitos diferentes de detetores gasosos microestruturados. O primeiro, baseado na microestrutura designada por 2D-Micro-Hole & Strip Plate (2D-MHSP) com uma área ativa de 3 3 cm2, enquanto que o segundo, baseado na estrutura 2D-Thick-COBRA (2D-THCOBRA) apresenta uma área ativa de deteção de 10 10 cm2. Estes detetores de raios-X de baixo custo têm a particularidade de funcionar em regime de fotão único permitindo a determinação da energia e posição de interação de cada fotão que chega ao detetor. Deste modo permitem detetar a energia dos fotões X de fluorescência, bem como obter imagens 2D da distribuição desses fotões X para o intervalo de energias desejado. São por isso adequados a aplicações de imagiologia de EDXRF. Os detetores desenvolvidos mostraram resoluções em energia de 17% e 22% para fotões incidentes com uma energia de 5.9 keV, respectivamente para o detetor 2D-MHSP e 2D-THCOBRA e resoluções em posição adequadas para um vasto número de aplicações. Ao longo deste trabalho é detalhado o desenvolvimento, o estudo das características e do desempenho de cada um dos detetores, e sua influência na performance final de cada sistema proposto. Numa fase mais avançada apresentam-se os resultados correspondentes à aplicação dos dois sistemas a diversas amostras, incluindo algumas do nosso património cultural e também uma amostra biológica.The present document describes the development and application of two energy dispersive X-ray fluorescence (EDXRF) imaging systems based on micropattern gaseous detectors. The X-ray fluorescence imaging technique is assumed as a powerful technique, non-destructive, on analysis of the spatial distribution of elements in materials. The imaging systems developed for EDXRF imaging consist of: an X-ray tube, acting as the external source to excite the sample; a micropattern gas detector; and a pinhole which directs the fluorescence radiation to the detector. On the other hand, the influence of the pinhole aperture diameter and the magnification factor obtained for the image in the position resolution of the system, is studied. Two different concepts of micropattern gaseous detectors were used. The first one is based on the 2D Micro-Hole & Strip Plate (2D-MHSP) microstructure with an active area of 3 3 cm2, while the second is based on the 2D Thick- COBRA (2D-THCOBRA) with a sensitive detection area of about 10 10 cm2. These X-ray detectors are single photon counting detectors, allowing the determination of the interaction position and energy of each photon reaching the detector. Therefore they can work as low cost energy dispersive detectors as well as obtain 2D images of the distribution of X photons for a range of energies required, which makes them suitable for EDXRF imaging applications. The detectors have shown an energy resolution of about 17% and 22% for 5.9 keV X-ray photons, for the 2D-MHSP detector and 2D THCOBRA, respectively, and apropriate spatial resolutions for a wide range of applications. Throughout this work, the development and study of the characteristics and the performance of each of the detectors used as well as their influence in the final performance of each proposed system is shown in detail. Results concerning the application of the two systems to several samples, including some cultural heritage samples and also a biological sample are shown

Social shaping of digital publishing: exploring the interplay between culture and technology

The processes and forms of electronic publishing have been changing since the advent of the Web. In recent years, the open access movement has been a major driver of scholarly communication, and change is also evident in other fields such as e-government and e-learning. Whilst many changes are driven by technological advances, an altered social reality is also pushing the boundaries of digital publishing. With 23 articles and 10 posters, Elpub 2012 focuses on the social shaping of digital publishing and explores the interplay between culture and technology. This book contains the proceedings of the conference, consisting of 11 accepted full articles and 12 articles accepted as extended abstracts. The articles are presented in groups, and cover the topics: digital scholarship and publishing; special archives; libraries and repositories; digital texts and readings; and future solutions and innovations. Offering an overview of the current situation and exploring the trends of the future, this book will be of interest to all those whose work involves digital publishing