1,721,045 research outputs found
Studies on Decision Diagrams for Efficient Manipulation of Sets and Strings
No full textIn many real-life problems, we are often faced with manipulating discrete structures.Manipulation of large discrete structures is one of the most important problems in computer science. For this purpose, a family of data structures calleddecision diagrams is used. The origin of the decision diagrams is binary decision diagram (BDD)proposed by Bryant in 1980s. BDD is a data structure to represent and manipulate Boolean functionsefficiently. As a variant of BDD, Minato proposedzero-suppressed binary decision diagram (ZDD). ZDD is a data structure for manipulating families of sets. In 2010, another descendant of BDD, sequence binary decision diagram (sequence BDD), is proposed byLoekito et al. This decision diagram represents sets of strings and allow computing string set operations, too.In this thesis, we study sequence BDD and ZDD. First, we show fundamental properties of sequence BDDs, such as the characterization of minimal sequence BDDs byreduced sequence BDDs, non-trivial relationships between sizes of minimal sequence BDDs and minimal Acyclic Deterministic Finite Automata, the complexities of minimization, Boolean set operations, and sequence BDD construction. Secondly, we alsodefine complete inverted files based on sequence BDD for directed acyclic graphs (DAGs).A complete inverted file is an abstract data type that provides various functions for text retrieval. We propose new complete inverted files calledSeqBDD-FPs for both texts and DAGs. We also present algorithms to construct them and to retrieve occurrence information from them. Thirdly, we pointed out the problem that is to build index for familiesof sets in order to store them compactly and allow fast searching. Then, we introduce DenseZDD, a compressed index for static ZDDs to solve a problem that current techniques for storing ZDDs require a huge amount of memory and membership operations are slow. Our technique not only indexes set families compactly but also executes fast membership operations. We also propose a hybrid method of DenseZDD and ordinaryZDDs to allow for dynamic indices.(主査) 教授 湊 真一, 教授 Zeugmann Thomas, 教授 有村博紀情報科学研究科（コンピュータサイエンス専攻
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
Testable and untestable classes of first-order formulae
Get PDFIn property testing, the goal is to distinguish structures that have some desired property from those that are far from having the property, based on only a small, random sample of the structure. We focus on the classification of first-order sentences according to their testability. This classification was initiated by Alon et al. [2], who showed that graph properties expressible with prefix there exists*for all* are testable but that there is an untestable graph property expressible with quantifier prefix for all*there exists*. The main results of the present paper are as follows. We prove that all (relational) properties expressible with quantifier prefix there exists*for all there exists* (Ackermann's class with equality) are testable and also extend the positive result of Alon et al. [2] to relational structures using a recent result by Austin and Tao [8]. Finally, we simplify the untestable property of Alon et al. [2] and show that prefixes for all(3)there exists, for all(2)there exists for all, for all there exists for all(2) and for all there exists V there exists can express untestable graph properties when equality is allowed
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