Search results for "MathematicsofComputing_DISCRETEMATHEMATICS"
showing 10 items of 123 documents
Fast and Simple Approximation of the Diameter and Radius of a Graph
2006
The increasing amount of data to be processed by computers has led to the need for highly efficient algorithms for various computational problems. Moreover, the algorithms should be as simple as possible to be practically applicable. In this paper we propose a very simple approximation algorithm for finding the diameter and the radius of an undirected graph. The algorithm runs in $O(m\sqrt{n})$ time and gives an additive error of $O(\sqrt{n})$ for a graph with n vertices and m edges. Practical experiments show that the results of our algorithm are close to the optimum and compare favorably to the 2/3-approximation algorithm for the diameter problem by Aingworth et al [1].
Games without repetitions on graphs with vertex disjoint cycles
1997
Games without repetitions on graphs with vertex disjoint cycles are considered. We show that the problem finding of the game partition in this class reduces to this problem for trees. A method of finding of the game partition for trees have been given in [2].
Two Parallel Algorithms for the Analysis of Random Images
1988
Aim of the paper is to show a computational paradigm, that reduces some algorithms on undirected graphs into image analysis algorithms. In particular two parallel algorithms on undirected weighted graphs, often used in the analysis of sparse images, are described.
Some subgroup embeddings in finite groups: A mini review
2015
[EN] In this survey paper several subgroup embedding properties related to some types of permutability are introduced and studied. ª 2014 Production and hosting by Elsevier B.V. on behalf of Cairo University
Vertical scratches detection based on edge detection for old film
2010
Automatic detection of image damaged regions is the key to automatic video image inpainting. Vertical scratches are the common damages in the old film. In this paper, a vertical scratches detection algorithm based on edge detection is proposed. The proposed algorithm first uses the operator which has the largest response to the vertical edge in Sobel operator to detect edges, and then uses canny operator to detect edges further. Third, we detect vertical lines in the image through probabilistic Hough transform. Finally, we obtain the true locations of the vertical lines scratches through morphology and width constraints. Many experiments show that our method can detect vertical line scratch…
Maximum Common Subgraph based locally weighted regression
2012
This paper investigates a simple, yet effective method for regression on graphs, in particular for applications in chem-informatics and for quantitative structure-activity relationships (QSARs). The method combines Locally Weighted Learning (LWL) with Maximum Common Subgraph (MCS) based graph distances. More specifically, we investigate a variant of locally weighted regression on graphs (structures) that uses the maximum common subgraph for determining and weighting the neighborhood of a graph and feature vectors for the actual regression model. We show that this combination, LWL-MCS, outperforms other methods that use the local neighborhood of graphs for regression. The performance of this…
Additional file 1 of Ethnobotany of the Aegadian Islands: safeguarding biocultural refugia in the Mediterranean
2021
Additional file 1. Ethnobiological uses of local taxa. Data table reporting the specific uses of local taxa documented in the present work and comparison to prior publications in the region. (.pdf file format).
Dynamic graph visualization
2011
Qualification work "Graph dynamic Visualization" describes the graph dynamic and development of display tool. Tool is designed to represent the changes in graph on a timeline. This allows the user to visually create the graph, change it and create views, saving all graph changes, and fetch information on the displayed graph views of the files. The tool is created in programming languageJava. The development is fully documented, including the requirement specification, design and testing. Keywords: graphs, dynamic graphs, graph display, Java.
The Steiner Traveling Salesman Problem and its extensions
2019
Abstract This paper considers the Steiner Traveling Salesman Problem, an extension of the classical Traveling Salesman Problem on an incomplete graph where not all vertices have demand. Some extensions including several depots or location decisions are introduced, modeled and solved. A compact integer linear programming formulation is proposed for each problem, where the routes are represented with two-index decision variables, and parity conditions are modeled using cocircuit inequalities. Exact branch-and-cut algorithms are developed for all formulations. Computational results obtained confirm the good performance of the algorithms. Instances with up to 500 vertices are solved optimally.
Distance graphs and the T-coloring problem
1999
Abstract The T-coloring problem is, given a graph G = (V, E), a set T of nonnegative integers containing 0, and a ‘span’ bound s ⩾ 0, to compute an integer coloring f of the vertices of G such that |f(ν) − f(w)| ∉ T ∀νw ∈ E and max f − min f ⩽ s. This problem arises in the planning of channel assignments for broadcast networks. When restricted to complete graphs, the T-coloring problem boils down to a number problem which can be solved efficiently for many types of sets T. The paper presents results indicating that this is not the case if the set T is arbitrary. To these ends, the class of distance graphs is introduced, which consists of all graphs G : G ≅ G(A) for some (finite) set of posi…