1,721,073 research outputs found
Distributed tasks : introducing distributed computing to programming competitions
Full text linkIn this paper we present distributed tasks, a new task type that can be used at programming competitions. In such tasks, a contestant is supposed to write a program which is then simultaneously executed on multiple computing nodes (machines). The instances of the program may communicate and use the joint computing power to solve the task presented to the contestant. We show a framework for running a contest with distributed tasks, that we believe to be accessible to contestants with no previous experience in distributed computing. Moreover, we give examples of distributed tasks that have been used in the last two editions of a Polish programming contest, Algorithmic Engagements, together with their intended solutions. Finally, we discuss the challenges of grading and preparing distributed tasks
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
Linear Time Construction of Cover Suffix Tree and Applications
Full text linkThe Cover Suffix Tree (CST) of a string is the suffix tree of with
additional explicit nodes corresponding to halves of square substrings of .
In the CST an explicit node corresponding to a substring of is
annotated with two numbers: the number of non-overlapping consecutive
occurrences of and the total number of positions in that are covered by
occurrences of in . Kociumaka et al. (Algorithmica, 2015) have shown how
to compute the CST of a length- string in time. We show how to
compute the CST in time assuming that is over an integer alphabet.
Kociumaka et al. (Algorithmica, 2015; Theor. Comput. Sci., 2018) have shown
that knowing the CST of a length- string , one can compute a linear-sized
representation of all seeds of as well as all shortest -partial
covers and seeds in for a given in time. Thus our result
implies linear-time algorithms computing these notions of quasiperiodicity. The
resulting algorithm computing seeds is substantially different from the
previous one (Kociumaka et al., SODA 2012, ACM Trans. Algorithms, 2020).
Kociumaka et al. (Algorithmica, 2015) proposed an -time algorithm
for computing a shortest -partial cover for each ;
we improve this complexity to .
Our results are based on a new characterization of consecutive overlapping
occurrences of a substring of in terms of the set of runs (see Kolpakov
and Kucherov, FOCS 1999) in . This new insight also leads to an -sized
index for reporting overlapping consecutive occurrences of a given pattern
of length in time, where is the number of
occurrences reported. In comparison, a general index for reporting bounded-gap
consecutive occurrences of Navarro and Thankachan (Theor. Comput. Sci., 2016)
uses space.Comment: Accepted to ESA 2023. Abstract abridged to satisfy arxiv requirement
Linear Time Construction of Cover Suffix Tree and Applications
Full text linkThe Cover Suffix Tree (CST) of a string T is the suffix tree of T with additional explicit nodes corresponding to halves of square substrings of T. In the CST an explicit node corresponding to a substring C of T is annotated with two numbers: the number of non-overlapping consecutive occurrences of C and the total number of positions in T that are covered by occurrences of C in T. Kociumaka et al. (Algorithmica, 2015) have shown how to compute the CST of a length-n string in (n log n) time. We give an algorithm that computes the same data structure in (n) time assuming that T is over an integer alphabet and discuss its implications.
A string C is a cover of text T if occurrences of C in T cover all positions of T; C is a seed of T if occurrences and overhangs (i.e., prefix-suffix occurrences) of C in T cover all positions of T. An α-partial cover (α-partial seed) of text T is a string C whose occurrences in T (occurrences and overhangs in T, respectively) cover at least α positions of T. Kociumaka et al. (Algorithmica, 2015; Theor. Comput. Sci., 2018) have shown that knowing the CST of a length-n string T, one can compute a linear-sized representation of all seeds of T as well as all shortest α-partial covers and seeds in T for a given α in (n) time. Thus our result implies linear-time algorithms computing these notions of quasiperiodicity. The resulting algorithm computing seeds is substantially different from the previous one (Kociumaka et al., SODA 2012, ACM Trans. Algorithms, 2020); in particular, it is non-recursive. Kociumaka et al. (Algorithmica, 2015) proposed an (n log n)-time algorithm for computing a shortest α-partial cover for each α = 1,…,n; we improve this complexity to (n).
Our results are based on a new combinatorial characterization of consecutive overlapping occurrences of a substring S of T in terms of the set of runs (see Kolpakov and Kucherov, FOCS 1999) in T. This new insight also leads to an (n)-sized index for reporting overlapping consecutive occurrences of a given pattern P of length m in the optimal (m+output) time, where output is the number of occurrences reported. In comparison, a general index for reporting bounded-gap consecutive occurrences of Navarro and Thankachan (Theor. Comput. Sci., 2016) uses (n log n) space
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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