1,720,992 research outputs found
Formal verification problems in a big data world : towards a mighty synergy
Full text linkFormal verification requires high performance data processing software for extracting knowledge from the unprecedented amount of data coming from analyzed systems. Since cloud based computing resources have became easily accessible, there is an opportunity for verification techniques and tools to undergo a deep technological transition to exploit the new available architectures. This has created an increasing interest in parallelizing and distributing verification techniques. In this paper we introduce a distributed approach which exploits techniques typically used by the bigdata community to enable verification of very complex systems using bigdata approaches and cloud computing facilities
Petri nets state space analysis in the cloud
No full textSeveral techniques for addressing the state space
explosion problem in model checking have been studied. One of these is to use distributed memory and computation for storing and exploring the state space of the model of a system. In this report, we present and compare different multithread, distributed, and cloud approaches to face the statespace explosion problem. The experiments report shows the convenience (in particular) of cloud approaches
A random glance at the flight deck: pilot's scanning strategies and the real-time assessment of mental workload
No full textBased on previous research showing the usefulness of spatial statistics in detecting randomness in the distribution of eye fixations, this study investigated the ocular behavior of professional pilots engaged in a simulated flight. The distribution of eye fixations was used as an indirect index of mental workload: Eye movements were recorded during the different phases (departure to landing) of a simulated flight and were analyzed using spatial statistics algorithms. Results showed sensitivity of spatial dispersion indices to variations in mental workload: higher during departure and landing, lower during climb and descend, and the lowest during the cruise phase. This finding provides additional evidence of the utility of fixations distribution as a real-time measure of mental workload and, consequently, as a trigger for adaptive automation
Coping with the State Explosion Problem in Formal Methods: Advanced Abstraction Techniques and Big Data Approaches.
Full text linkFormal verification of dynamic, concurrent and real-time systems has been the focus of several decades of software engineering research. Formal verification requires high-performance data processing software for extracting knowledge from the unprecedented amount of data containing all reachable states and all transitions that systems can make among those states, for instance, the extraction of specific reachable states, traces, and more. One of the most challenging task in this context is the development of tools able to cope with the complexity of real-world models analysis. Many methods have been proposed to alleviate this problem. For instance, advanced state space techniques aim at reducing the data needed to be constructed in order to verify certain properties. Other directions are the efficient implementation of such analysis techniques, and studying ways to parallelize the algorithms in order to exploit multi-core and distributed architectures. Since cloud-based computing resources have became easily accessible, there is an opportunity for verification techniques and tools to undergo a deep technological transition to exploit the new available architectures. This has created an increasing interest in parallelizing and distributing verification techniques. Cloud computing is an emerging and evolving paradigm where challenges and opportunities allow for new research directions and applications. There is an evidence that this trend will continue, in fact several companies are putting remarkable efforts in delivering services able to offer hundreds, or even thousands, commodity computers available to customers, thus enabling users to run massively parallel jobs. This revolution is already started in different scientific fields, achieving remarkable breakthroughs through new kinds of experiments that would have been impossible only few years ago. Anyway, despite many years of work in the area of multi-core and distributed model checking, still few works introduce algorithms that can scale effortlessly to the use of thousands of loosely connected computers in a network, so existing technology does not yet allow us to take full advantage of the vast array of compute power of a "cloud" environment. Moreover, despite model checking software tools are so called "push-button", managing a high-performance computing environment required by distributed scientific applications, is far from being considered such, especially whenever one wants to exploit general purpose cloud computing facilities.
The thesis focuses on two complementary approaches to deal with the state explosion problem in formal verification. On the one hand we try to decrease the exploration space by studying advanced state space methods for real-time systems modeled with Time Basic Petri nets. In particular, we addressed and solved several different open problems for such a modeling formalism. On the other hand, we try to increase the computational power by introducing approaches, techniques and software tools that allow us to leverage the "big data" trend to some extent. In particular, we provided frameworks and software tools that can be easily specialized to deal with the construction and verification of very huge state spaces of different kinds of formalisms by exploiting big data approaches and cloud computing infrastructures
Immagini del mondo. Il villaggio tribale di Mohuda, India
No full textL’intervento qui proposto si prefigge di raccontare l’esperienza condotta, in relazione all’attivita’ di preparazione di una Tesi di laurea in Architettura, nel villaggio tribale di Mohuda, in India, nella regione di Orissa.
In particolare vuole descrivere le difficolta’ incontrate nel tentativo di comprendere uno spazio rururbano, che noi occidentali definiremmo semplicemente caotico, in cui i nostri usuali metodi e strumenti analitici si sono immediatamente dimostrati incapaci di penetrare nella struttura di una realta’ cosi’ profondamente diversa e distante.
A tale difficolta’ originaria, si aggiunga l’assoluta mancanza di una documentazione di base per cosi’ dire di tipo tradizionale - planimetrie, ma anche foto aeree, ecc. - e una continua espansione edilizia, peraltro coordinata da una ONG, ovvero un accrescimento delle singole cellule-unita’ abitative al di fuori di ogni esplicito e visibile disegno ordinatore generale.
Per questo si e’ ritenuto opportuno sperimentare forme descrittive diverse e giustapposte: video, appunti di viaggio, ma soprattutto interviste, a giovani e vecchi, a donne e uomini, orali, scritte, disegnate.
In questo modo il villaggio ha preso forma, e la complessita’ si e’ organizzata in sistema: dalla “piazza” principale il sistema delle strade - la rete di quelle interne al villaggio e il collegamento con la citta’ piu’ vicina -, il sistema dell’acqua – dai punti di raccolta al laghetto artificiale e alla cisterna -, ma soprattutto il sistema dei templi, disposti secondo geometrie certe a dare senso e forma all’apparente informalita’ del villaggio
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Distributed CTL model checking using MapReduce : theory and practice
No full textThe recent extensive availability of 'cloud' computing platforms is very appealing for the formal verification community. In fact, these platforms represent a great opportunity to run massively parallel jobs and analyze 'big data' problems, although classical formal verification tools and techniques must undergo a deep technological transformation to take advantage of the available powerful architectures. A distributed approach to verification of computation tree logic formulas on very large state spaces is described. The approach exploits and integrates our parametric state-space builder, designed to ease the adoption of 'big data' platforms. The whole framework adopts a MAPREDUCEapproach as the core computational model and can be tailored to different modeling formalisms. This paper includes proofs of correctness, a short theoretical discussion about complexity, and reports a practical experience with some benchmarking Petri net models. The outcomes of several tests are presented, thus showing the convenience of the proposed approach
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