1,721,036 research outputs found
Robust distributed cooperation in the presence of quantified adversity
No full textThe ability to cooperatively perform a collection of tasks in a distributed setting is key to solving a broad range of computation problems ranging from distributed search to distributed simulation and multi-agent collaboration. Do-All, an abstraction of such cooperative activity, is the problem of using p processors to cooperatively perform n independent and idempotent tasks in the presence of adversity. The Do-All problem can be used to identifying the trade-offs between efficiency and fault-tolerance in distributed cooperative computing. Solutions for Do-All may yield insight leading to efficient and fault-tolerant algorithms for distributed co-operation. Although significant research was dedicated to studying Do-All, prior work offers only a partial understanding of this problem. In particular, while prior work shows how to achieve fault-tolerance in the presence of adversity, it does not adequately teach how the adverse environment affects the efficiency of Do-All solutions. This thesis substantially increases this understanding. One of the contributions includes failure sensitive upper and lower bounds for Do-All in certain models of computation, that show how failures affect the efficiency of Do-All solutions. The upper/lower bounds are given as functions of n, p and f, the number of failures caused by the adverse environment. Another contribution of the thesis is the definition and analysis of the iterative Do-All problem, that models the repetitive use of Do-All algorithms, such as found in typical algorithm simulations. ^ This thesis also studies the distributed cooperation problem in partitionable networks, where partitions may interfere with the progress of the computation. Group communication services are used to develop robust algorithms for this settings. Moreover, it is shown that it is possible to obtain optimally-competitive scheduling algorithms in partitionable networks by proving upper and lower bound results. These results demonstrate precisely how partitions affect the efficiency of computation. ^ Overall, the thesis is substantially contributing to the study of the trade-offs between efficiency and fault-tolerance in cooperative computing and is advancing the state-of-the-art in principles of robust distributed computing.
Principles of Blockchain Systems
No full textThis book is the first to present the state of the art and provide technical focus on the latest advances in the foundations of blockchain systems. It is a collaborative work between specialists in cryptography, distributed systems, formal languages, and economics, and addresses hot topics in blockchains from a theoretical perspective: cryptographic primitives, consensus, formalization of blockchain properties, game theory applied to blockchains, and economical issues.
This book reflects the expertise of the various authors, and is intended to benefit researchers, students, and engineers who seek an understanding of the theoretical foundations of blockchains.TRUEpu
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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