1,721,092 research outputs found
A Q-Convexity Vector Descriptor for Image Analysis
No full textShape representation is a main problem in computer vision, and shape descriptors are widely used for image analysis. In this paper, based on the previous work Balázs, P., Brunetti, S.: A New Shape Descriptor Based on a Q-convexity Measure, Lecture Notes in Computers Science 10502, 20th Discrete Geometry for Computer Imagery (DGCI) (2017) 267–278, we design a new convexity vector descriptor derived by the notion of the so-called generalized salient points matrix. We investigate properties of the vector descriptor, such as scale invariance and its behavior in a ranking task. Moreover, we present results on a binary and a multiclass classification problem using k-nearest neighbor, decision tree, and support vector machine methods. Results of these experiments confirm the good behavior of our proposed descriptor in accuracy, and its performance is comparable and, in some cases, superior to some recently published similar methods
Determination of Q-convex bodies by X-rays
No full textThe class of Q-convex bodies is defined, and the uniqueness result proved by Gardner and McMullen in 1980 for planar convex bodies is extended to this new class
Stability results for the reconstruction of binary pictures from two projections
No full textIn the present paper we mathematically prove several stability results concerning the problem of reconstructing binary pictures from their noisy projections taken from two directions. Stability is a major requirement in practice, because projections are often affected by noise due to the nature of measurements. Reconstruction from projections taken along more than two directions is known to be a highly unstable task. Contrasting this result we prove several theorems showing that reconstructions from two directions closely resemble the original picture when the noise level is low and the original picture is uniquely determined by its projections
On the polynomial 1/[n]q [kn] q
No full textIn the work The Friedman–Joichi–Stanton Monotonicity Conjecture at Primes, George Andrews gave a proof of the fact (first mentioned by Jim Propp a while ago) that the q-binomial coefficient View the MathML source divided by the q-integer [n]q is a polynomial in q, as long as n and k are relatively prime (see [G.E. Andrews, The Friedman–Joichi–Stanton Monotonicity Conjecture at Primes, in: DIMACS Ser., Amer. Math. Soc., in press, Theorem 2]). In this note we provide a proof that permits to generalize Theorem 2 in the case in which n and k are not relatively prime, and further, to extend Theorem 2 to the q-multinomial coefficient
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
Reconstruction of Q-convex lattice sets
No full textWe present a class od lattice sets for which there are unique determination and a polynomial time reconstruction algorithm by X-rays in suitable directions. Moreover many reconstructions of different classes of lattice sets having convexity/connnectivity constrains can be seen as particular cases of the former case
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
On the computational complexity of determining three dimensional lattice sets from their three dimensional X-rays
No full textA generalization of a classical discrete tomography problem is considered: reconstruct three-dimensional lattice sets from their two-dimensional X-rays parallel to three coordinate planes. First, we prove that this reconstruction problem is NP-hard. Then we propose some greedy algorithms that provide approximate solutions of the problem
- …
