1,720,957 research outputs found
Remarks on Ultrametrics and Metric-Preserving Functions
Full text linkFunctions whose composition with every metric is a metric are said to be metric-preserving. In this paper, we investigate a variation of the concept of metric-preserving functions where metrics are replaced by ultrametrics
Fixed Point Theorem of Half-Continuous Mappings on Topological Vector Spaces
No full textSome fixed point theorems of half-continuous mappings which are possibly discontinuous defined on topological vector spaces are presented. The results generalize the work of Philippe Bich (2006) and several well-known results
เงื่อนไขที่เพียงพอบางประการสำหรับแนววิถีที่เป็นวัฏจักรที่คล้ายคลึงกับปัญหา 3x+1 ใน 2 มิติ
Full text linkThesis (M.Sc.)--Chulalongkorn University, 2001The 3x+1 problem concerns the behavior of the iterates of the function defined by T(x) = (3x+1)/2 if x is odd, T(x) = x/2 if x is even. The 3x+1 Conjecture asserts that, starting from any positive integer alpha , repeated iteration of this function eventually produces the value 1. In this thesis we study the following extended version of the above problem. Let Z* be the set of all nonnegative integers. Let k be any fixed prime number and D=[k 0], D=[0 k] Let A be any 2x2 matrix of positive integers. For a fixed beta is an element of a set Z*2, let T: Z*2 -> Z*2 be defined by, for each alpha is an element of a set Z*2, T(alpha) = D-1 alpha if D-1 alpha is an element of a set Z*2, T(alpha) = A alpha + beta if D-1 alpha is not an element of a set Z*2. The research reported in this thesis concerns determining whether or not the trajectory [alpha, T(alpha), T2 (alpha), ...] is cyclic. For some forms of the matrix A it is proved that the trajectory cannot be cyclic for any choice of beta is an element of a set Z*2. In some other cases values of beta are given which ensure a cyclic trajectory.ปัญหา 3x+1 เป็นปัญหาเกี่ยวกับพฤติกรรมของการดำเนินการซ้ำของฟังก์ชันซึ่งนิยามโดย T(x) =(3x+1)/2 เมื่อ x เป็นจำนวนคี่, T(x) = x/2 เมื่อ x เป็นจำนวนคู่ ข้อความคาดการณ์ 3x+1 กล่าวว่า ถ้าเริ่มต้นจากจำนวนเต็มบวก alpha ใด ๆ ดำเนินการส่งด้วย ฟังก์ชันข้างต้นซ้ำๆ กันในที่สุดจะได้ค่าเป็น 1 ในวิทยานิพนธ์ฉบับนี้เราจะขยายการศึกษาปัญหาดังกล่าวดังนี้ ให้ Z* เป็นเซตของจำนวนเต็มที่ไม่เป็นลบทั้งหมด ให้ k เป็นจำนวนเฉพาะคงที่และ D=[k 0], D=[0 k] ให้ A เป็นเมตริกซ์ของจำนวนเต็มบวกขนาด 2x2 ใดๆ สำหรับแต่ละค่า beta ที่คงที่ใน Z*2 ให้ T: Z*2 -> Z*2 กำหนดโดย สำหรับแต่ละ alpha is an element of a set Z*2, T(alpha) = D-1 alpha if D-1 alpha is an element of a set Z*2, T(alpha) = A alpha + beta if D-1 alpha is not an element of a set Z*2 ผลการวิจัยที่รายงานในวิทยานิพนธ์ฉบับนี้เกี่ยวกับการยืนยันว่าแนววิถี [alpha, T(alpha), T2 (alpha),...] จะเป็นวัฏจักรหรือไม่ เราพิสูจน์ว่าสำหรับเมตริกซ์ A บางรูปแบบแนววิถีไม่เป็นวัฏจักรไม่ว่าจะเลือก beta is an element of a set Z*2 เป็นค่าใดก็ตามและสำหรับเมตริกซ์ A บางรูปแบบค่าของ beta ที่กำหนดให้จะรับประกันได้ว่าแนววิถีจะเป็นวัฏจัก
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
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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