A visibility representation of a graph G is to represent the nodes of G with non-overlapping horizontal line segments such that the line segments representing any two distinct adjacent nodes are vertically visible to each other. If G is a plane graph, i.e., a planar graph equipped with a planar embedding, a visibility representation of G has the additional requirement of reflecting the given pl...

introduction: a variety of mesial and distal projections have been suggested for separating the canals in a multi-canaled root. but there is no general agreement on the best angulation for each tooth. the purpose of this study was to evaluate the x-ray horizontal angle for separating the canals of four-canal first mandibular molars. materials and methods: forty four-canaled mandibular molars we...

Let S be a set of horizontal line segments, or bars, in the plane. We say that G is a bar visibility graph, and S its bar visibility representation, if there exists a one-to-one correspondence between vertices of G and bars in S, such that there is an edge between two vertices in G if and only if there exists an unobstructed vertical line of sight between their corresponding bars. If bars are a...

introduction thermal infrared integrated dust index (tiidi) is one of indices that is presented in this direction. the index operates based on four brightness temperature difference including wavelengths 3.7, 8.6, 11 and 12 micrometer. according to the studies, btd (bt12-bt11) is used for cloud detection. btd (bt8.6-bt11) is the index for separation for dust from sandy surface and btd (bt3.7-bt...

This paper considers representations of graphs as rectangle-visibility graphs and as doubly linear graphs. These are, respectively, graphs whose vertices are isothetic rectangles in the plane with adjacency determined by horizontal and vertical visibility, and graphs that can be drawn as the union of two straight-edged planar graphs. We prove that these graphs have, with n vertices, at most 6n−...