Takeshi Tokuyama Authors: Add personal information
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 Average citations per article 6.19 Citation Count 731 Publication count 118 Publication years 1990-2018 Available for download 30 Average downloads per article 514.00 Downloads (cumulative) 15,420 Downloads (12 Months) 293 Downloads (6 Weeks) 46
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V. Bibliometrics: Citation Count: 0 We study an algorithmic problem that is motivated by ink minimization for sparse set visualizations. Our input is a set of points in the plane which are either blue, red, or purple. Blue points belong exclusively to the blue set, red points belong exclusively to the red set, and purple ... Keywords: Approximation, Colored point set, Minimum spanning tree, Matroid intersection, Set visualization 2 November 2017 Discrete Optimization: Volume 26 Issue C, November 2017 Publisher: Elsevier Science Publishers B. V. Bibliometrics: Citation Count: 0 We discuss an online discrete optimization problem called the buyback problem. In the literature of the buyback problem, the valuation function representing the total value of selected elements is given by a linear function. In this paper, we consider a generalization of the buyback problem using nonlinear valuation functions. We ... Keywords: Discrete concave function, Online discrete optimization problem, Gross substitutes valuation, Matroid, Buyback problem 3 October 2017 Algorithmica: Volume 79 Issue 2, October 2017 Publisher: Springer-Verlag New York, Inc. Bibliometrics: Citation Count: 0 We study the problem of efficiently correcting an erroneous product of two $$n\times n$$n?n matrices over a ring. Among other things, we provide a randomized algorithm for correcting a matrix product with at most k erroneous entries running in $${\tilde{O}}(n^2+kn)$$O~(n2+kn) time and a deterministic $${\tilde{O}}(kn^2)$$O~(kn2)-time algorithm for this problem (where ... Keywords: Matrix product correction, Time complexity, Randomized algorithms, Matrix multiplication, Matrix product verification 4 December 2014 Theoretical Computer Science: Volume 553 Issue C, October, 2014 Publisher: Elsevier Science Publishers Ltd. Bibliometrics: Citation Count: 0 Network localization is important for networks with no prefixed positions of network nodes such as sensor networks. We are given a subset of the set of ( n 2 ) pairwise distances among n sensors in some Euclidean space. We want to determine the positions of each sensor from the ... Keywords: Connected dominating set, Point set reconstruction, Weighted graph embedding, Chordal graph, Graph turnpike problem, Network localization 5 October 2014 Theoretical Computer Science: Volume 555 Issue C, October 2014 Publisher: Elsevier Science Publishers Ltd. Bibliometrics: Citation Count: 0 A base-monotone region with a base is a subset of the cells in a pixel grid such that if a cell is contained in the region then so are the ones on a shortest path from the cell to the base. The problem of decomposing a pixel grid into disjoint ... Keywords: Base-monotone region, Computational complexity, Image segmentation, Room-Edge Problem 6 October 2014 Algorithmica: Volume 70 Issue 2, October 2014 Publisher: Springer-Verlag New York, Inc. Bibliometrics: Citation Count: 0 Given a set of line segments in the plane, not necessarily finite, what is a convex region of smallest area that contains a translate of each input segment? This question can be seen as a generalization of Kakeya's problem of finding a convex region of smallest area such that a ... Keywords: Computational geometry, Kakeya, Discrete geometry, Algorithms 7 June 2014 SOCG'14: Proceedings of the thirtieth annual symposium on Computational geometry Publisher: ACM Bibliometrics: Citation Count: 0 Downloads (6 Weeks): 1,   Downloads (12 Months): 10,   Downloads (Overall): 105 Full text available: PDF Given a polygonal region containing a target point (which we assume is the origin), it is not hard to see that there are two points on the perimeter that are antipodal, i.e., whose midpoint is the origin. We prove three generalizations of this fact. (1) For any polygon (or any ... Keywords: Borsuk-Ulam theorem, skeleton of polyhedra, Antipodal pair, Minkowski sum, balancing, barycenter 8 March 2014 Theoretical Computer Science: Volume 525, March, 2014 Publisher: Elsevier Science Publishers Ltd. Bibliometrics: Citation Count: 13 We introduce a new string matching problem called order-preserving matching on numeric strings, where a pattern matches a text if the text contains a substring of values whose relative orders coincide with those of the pattern. Order-preserving matching is applicable to many scenarios such as stock price analysis and musical ... Keywords: Multiple pattern matching, Numeric string, String matching, Aho-Corasick algorithm, Order relation, KMP algorithm 9 September 2013 ACM Transactions on the Web (TWEB): Volume 7 Issue 3, September 2013 Publisher: ACM Bibliometrics: Citation Count: 4 Downloads (6 Weeks): 3,   Downloads (12 Months): 18,   Downloads (Overall): 595 Full text available: PDF Image annotation is a process of finding appropriate semantic labels for images in order to obtain a more convenient way for indexing and searching images on the Web. This article proposes a novel method for image annotation based on combining feature-word distributions, which map from visual space to word space, ... Keywords: topic models, image annotation, probabilistic Latent Semantic Analysis (pLSA), Gaussian mixtures, Image retrieval, multi-instance multi-label learning 10 April 2012 LATIN'12: Proceedings of the 10th Latin American international conference on Theoretical Informatics Publisher: Springer-Verlag Bibliometrics: Citation Count: 1 We consider the following geometric alignment problem: Given a set of line segments in the plane, find a convex region of smallest area that contains a translate of each input segment. This can be seen as a generalization of Kakeya's problem of finding a convex region of smallest area such ... 11 September 2011 ALGOSENSORS'11: Proceedings of the 7th international conference on Algorithms for Sensor Systems, Wireless Ad Hoc Networks and Autonomous Mobile Entities Publisher: Springer-Verlag Bibliometrics: Citation Count: 0 Network localization is important for networks with no prefixed positions of network nodes such as sensor networks. We are given a subset of the set of $\binom{n}{2}$ pairwise distances among n sensors in some Euclidean space. We want to determine the ... Keywords: network localization, chordal graph, point set reconstruction, weighted graph embedding, connected dominating set, graph turnpike problem 12 November 2010 Computational Geometry: Theory and Applications: Volume 43 Issue 9, November, 2010 Publisher: Elsevier Science Publishers B. V. Bibliometrics: Citation Count: 1 The bisector of two nonempty sets P and Q in R^d is the set of all points with equal distance to P and to Q. A distance k-sector of P and Q, where k>=2 is an integer, is a (k-1)-tuple (C"1,C"2,...,C"k"-"1) such that C"i is the bisector of C"i"-"1 and ... Keywords: Distance k-sectors, Knaster-Tarski fixed point theorem 13 October 2010 CIKM '10: Proceedings of the 19th ACM international conference on Information and knowledge management Publisher: ACM Bibliometrics: Citation Count: 3 Downloads (6 Weeks): 5,   Downloads (12 Months): 8,   Downloads (Overall): 342 Full text available: PDF Image annotation is to automatically associate semantic labels with images in order to obtain a more convenient way for indexing and searching images on the Web. This paper proposes a novel method for image annotation based on feature-word and word-topic distributions. The introduction of topics enables us to efficiently take ... Keywords: mixture hierarchies, topic models, image annotation 14 July 2010 COCOON'10: Proceedings of the 16th annual international conference on Computing and combinatorics Publisher: Springer-Verlag Bibliometrics: Citation Count: 1 We consider the optimization problem of finding k nonintersecting rectangles and tableaux in n × n pixel plane where each pixel has a real valued weight. We discuss existence of efficient algorithms if a corner point of each rectangle/tableau is specified. 15 June 2010 SoCG '10: Proceedings of the twenty-sixth annual symposium on Computational geometry Publisher: ACM Bibliometrics: Citation Count: 2 Downloads (6 Weeks): 1,   Downloads (12 Months): 5,   Downloads (Overall): 110 Full text available: PDF The bisector of two nonempty sets P and Q in a metric space is the set of all points with equal distance to P and to Q . A distance k-sector of P and Q , where k ≥ 2 is an integer, is a ( k -1)-tuple ( C ... Keywords: knaster-tarski fixed point theorem, distance k-sectors 16 June 2010 SoCG '10: Proceedings of the twenty-sixth annual symposium on Computational geometry Publisher: ACM Bibliometrics: Citation Count: 4 Downloads (6 Weeks): 2,   Downloads (12 Months): 6,   Downloads (Overall): 167 Full text available: PDF Zone diagram is a variation on the classical concept of a Voronoi diagram. Given n sites in a metric space that compete for territory, the zone diagram is an equilibrium state in the competition. Formally it is defined as a fixed point of a certain "dominance" map. Asano, Matousek, and ... Keywords: knaster-tarski fixed point theorem, zone diagrams 17 January 2010 Algorithmica - Special Issue: Algorithms and Computation; Guest Editor: Takeshi Tokuyama: Volume 56 Issue 1, January 2010 Publisher: Springer-Verlag New York, Inc. Bibliometrics: Citation Count: 0 18 January 2010 Algorithmica: Volume 56 Issue 1, January 2010 Publisher: Springer-Verlag New York, Inc. Bibliometrics: Citation Count: 0 19 December 2009 ISAAC '09: Proceedings of the 20th International Symposium on Algorithms and Computation Publisher: Springer-Verlag Bibliometrics: Citation Count: 5 Motivated from the image segmentation problem, we consider the problem of finding the maximum weight region with a shape decomposable into elementary shapes in n ? n pixel grid where each pixel has a real valued weight. We give efficient algorithms for several interesting cases. This shows string constrast to ... 20 October 2009 Discrete & Computational Geometry: Volume 42 Issue 3, October 2009 Publisher: Springer-Verlag New York, Inc. Bibliometrics: Citation Count: 0 Given a fixed origin o in the d-dimensional grid, we give a novel definition of digital rays dig(op) from o to each grid point p. Each digital ray dig(op) approximates the Euclidean line segment $\overline {op}$ between o and p. The set of all digital rays satisfies a set of ... Keywords: Tree embedding, Discrete geometry, Digital geometry, Star-shaped regions

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