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A class of surfaces-graphs in a Riemannian 3-space with a prescribed projection of one field of principal directions onto a surface $\Pi$ is considered. A problem of determination of such surfaces when both principal curvatures are given…

Differential Geometry · Mathematics 2010-03-11 Vladimir Rovenski , Leonid Zelenko

Let $P=A_1\ldots A_n$ be a generic polygon in three-dimensional space and let $v_1,v_2,\ldots,v_n$ be vectors $\overline{A_1A_2},\overline{A_2A_3},\ldots,\overline{A_nA_1}$, respectively. $P$ will be called \emph{regular}, if there exist…

Metric Geometry · Mathematics 2020-04-28 Yury Kochetkov

We study a fundamental question from graph drawing: given a pair $(G,C)$ of a graph $G$ and a cycle $C$ in $G$ together with a simple polygon $P$, is there a straight-line drawing of $G$ inside $P$ which maps $C$ to $P$? We say that such a…

Computational Geometry · Computer Science 2021-03-15 Tim Ophelders , Ignaz Rutter , Bettina Speckmann , Kevin Verbeek

Given a Poisson process on a bounded interval, its random geometric graph is the graph whose vertices are the points of the Poisson process and edges exist between two points if and only if their distance is less than a fixed given…

Probability · Mathematics 2010-08-31 Laurent Decreusefond , Eduardo Ferraz

IC-planar graphs are those graphs that admit a drawing where no two crossed edges share an end-vertex and each edge is crossed at most once. They are a proper subfamily of the 1-planar graphs. Given an embedded IC-planar graph $G$ with $n$…

Computational Geometry · Computer Science 2016-07-19 Franz J. Brandenburg , Walter Didimo , William S. Evans , Philipp Kindermann , Giuseppe Liotta , Fabrizio Montecchiani

Gradients of the perimeter and area of a polygon have straightforward geometric interpretations. The use of optimality conditions for constrained problems and basic ideas in triangle geometry show that polygons with prescribed area…

Metric Geometry · Mathematics 2023-09-13 Beniamin Bogosel

We study straight-line drawings of planar graphs with prescribed face areas. A plane graph is 'area-universal' if for every area assignment on the inner faces, there exists a straight-line drawing realizing the prescribed areas. For…

Computational Geometry · Computer Science 2018-09-05 Linda Kleist

Let $P$ be a set of $n$ points in the plane. A crossing-free structure on $P$ is a plane graph with vertex set $P$. Examples of crossing-free structures include triangulations of $P$, spanning cycles of $P$, also known as polygonalizations…

Computational Geometry · Computer Science 2013-12-18 Victor Alvarez , Karl Bringmann , Radu Curticapean , Saurabh Ray

Visibility graph of a simple polygon is a graph with the same vertex set in which there is an edge between a pair of vertices if and only if the segment through them lies completely inside the polygon. Each pair of adjacent vertices on the…

Computational Geometry · Computer Science 2020-02-18 Hossein Boomari Soheila Farokhi

We study the problem of stabbing rectilinear polygons, where we are given $n$ rectilinear polygons in the plane that we want to stab, i.e., we want to select horizontal line segments such that for each given rectilinear polygon there is a…

Computational Geometry · Computer Science 2024-02-06 Arindam Khan , Aditya Subramanian , Tobias Widmann , Andreas Wiese

A $3$-uniform hypergraph is a generalization of simple graphs where each hyperedge is a subset of vertices of size $3$. The degree of a vertex in a hypergraph is the number of hyperedges incident with it. The degree sequence of a hypergraph…

Combinatorics · Mathematics 2023-12-04 Runze Li , Istvan Miklos

A simple-triangle graph is the intersection graph of triangles that are defined by a point on a horizontal line and an interval on another horizontal line. The time complexity of the recognition problem for simple-triangle graphs was a…

Discrete Mathematics · Computer Science 2018-09-20 Asahi Takaoka

We construct a polygonal spiral by arranging a sequence of regular $n$-gons such that each $n$-gon shares a specified side and vertex with the $(n+1)$-gon in the construction. By offering flexibility for determining the size of each $n$-gon…

Metric Geometry · Mathematics 2024-04-16 Kyle Fridberg

A geometric graph is a graph whose vertices are points in general position in the plane and its edges are straight line segments joining these points. In this paper we give an $O(n^2 \log n)$ algorithm to compute the number of pairs of…

Computational Geometry · Computer Science 2020-09-04 Frank Duque , Ruy Fabila-Monroy , César Hernández-Vélez , Carlos Hidalgo-Toscano

We define a simple orthogonal polyhedron to be a three-dimensional polyhedron with the topology of a sphere in which three mutually-perpendicular edges meet at each vertex. By analogy to Steinitz's theorem characterizing the graphs of…

Computational Geometry · Computer Science 2016-08-12 David Eppstein , Elena Mumford

Point-set embeddings and large-angle crossings are two areas of graph drawing that independently have received a lot of attention in the past few years. In this paper, we consider problems in the intersection of these two areas. Given the…

Data Structures and Algorithms · Computer Science 2011-07-26 Martin Fink , Jan-Henrik Haunert , Tamara Mchedlidze , Joachim Spoerhase , Alexander Wolff

We study the problem of finding maximum-area triangles that can be inscribed in a polygon in the plane. We consider eight versions of the problem: we use either convex polygons or simple polygons as the container; we require the triangles…

Computational Geometry · Computer Science 2020-07-27 Seungjun Lee , Taekang Eom , Hee-Kap Ahn

A simple-triangle graph (also known as a PI graph) is the intersection graph of a family of triangles defined by a point on a horizontal line and an interval on another horizontal line. The recognition problem for simple-triangle graphs was…

Discrete Mathematics · Computer Science 2017-04-04 Asahi Takaoka

Obstacle representations of graphs have been investigated quite intensely over the last few years. We focus on graphs that can be represented by a single obstacle. Given a (topologically open) polygon $C$ and a finite set $P$ of points in…

Computational Geometry · Computer Science 2016-09-02 Steven Chaplick , Fabian Lipp , Ji-won Park , Alexander Wolff

An obstacle representation of a graph $G$ is a set of points in the plane representing the vertices of $G$, together with a set of polygonal obstacles such that two vertices of $G$ are connected by an edge in $G$ if and only if the line…

Combinatorics · Mathematics 2017-07-18 Martin Balko , Josef Cibulka , Pavel Valtr