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Suppose that a polygon $P$ is given as an array containing the vertices in counterclockwise order. We analyze how many vertices (including the index of each of these vertices) we need to know before we can bound $P$, i.e., report a bounded…

Computational Geometry · Computer Science 2025-09-05 Mikkel Abrahamsen , Jack Stade , Shuyi Yan , Hanwen Zhang

We study the Hamiltonian path problem in C-shaped grid graphs, and present the necessary and sufficient conditions for the existence of a Hamiltonian path between two given vertices in these graphs. We also give a linear-time algorithm for…

Computational Complexity · Computer Science 2016-02-25 Fatemeh Keshavarz-Kohjerdi , Alireza Bagheri

Generalizing pseudospherical drawings, we introduce a new class of simple drawings, which we call separable drawings. In a separable drawing, every edge can be closed to a simple curve that intersects each other edge at most once. Curves of…

Computational Geometry · Computer Science 2024-10-15 Oswin Aichholzer , Joachim Orthaber , Birgit Vogtenhuber

The purpose of this note is to give a simple proof for a necessary and sufficient condition for visibility paths in simple polygons. A visibility path is a curve such that every point inside a simple polygon is visible from at least one…

Computational Geometry · Computer Science 2022-12-05 Mohammad Reza Zarrabi , Nasrollah Moghaddam Charkari

This paper investigates the problem of listing faces of combinatorial polytopes, such as hypercubes, permutahedra, associahedra, and their generalizations. Firstly, we consider the face lattice, which is the inclusion order of all faces of…

Real-world graphs often manifest as a massive temporal stream of edges. The need for real-time analysis of such large graph streams has led to progress on low memory, one-pass streaming graph algorithms. These algorithms were designed for…

Data Structures and Algorithms · Computer Science 2014-10-16 Madhav Jha , C. Seshadhri , Ali Pinar

We present a tight extremal threshold for the existence of Hamilton cycles in graphs with large minimum degree and without a large ``bipartite hole`` (two disjoint sets of vertices with no edges between them). This result extends Dirac's…

Combinatorics · Mathematics 2016-04-20 Colin McDiarmid , Nikola Yolov

The edges surrounding a face of a map $M$ form a cycle $C$, called the boundary cycle of the face, and $C$ is often not a simple cycle. If the map $M$ is arc-transitive, then there is a cyclic subgroup of automorphisms of $M$ which leaves…

Combinatorics · Mathematics 2021-11-05 Jiyong Chen , Cai Heng Li , Cheryl E. Praeger , Shu-Jiao Song

We consider a refinement of the partition function of graph homomorphisms and present a quasi-polynomial algorithm to compute it in a certain domain. As a corollary, we obtain quasi-polynomial algorithms for computing partition functions…

Combinatorics · Mathematics 2015-08-04 Alexander Barvinok , Pablo Soberón

Detecting polygons defined by a set of line segments in a plane is an important step in analyzing vector drawings. This paper presents an approach combining several algorithms to detect basic polygons from arbitrary line segments. The…

Computational Geometry · Computer Science 2023-12-29 Alfredo Ferreira , Manuel J. Fonseca , Joaquim A. Jorge

A (general) polygonal line tiling is a graph formed by a string of cycles, each intersecting the previous at an edge, no three intersecting. In 2022, Matsushita proved the matching complex of a certain type of polygonal line tiling with…

Combinatorics · Mathematics 2023-03-13 Margaret Bayer , Marija Jelić Milutinović , Julianne Vega

We devise the following dynamic algorithms for both maintaining as well as querying for the visibility and weak visibility polygons amid vertex insertions and/or deletions to the simple polygon. * A fully-dynamic algorithm for maintaining…

Computational Geometry · Computer Science 2020-04-21 R. Inkulu , K. Sowmya , N. P. Thakur

A $triangulation$ is an embedding of a graph on surfaces where every face has length three. In this article, we show the existence of contractible Hamiltonian cycle in triangulated maps of which minimum degree is four.

Combinatorics · Mathematics 2014-07-14 Dipendu Maity , Ashish Kumar Upadhyay

A step forward is made in a long standing Lov\'{a}sz's problem regarding hamiltonicity of vertex-transitive graphs by showing that every connected vertex-transitive graph of order a product of two primes, other than the Petersen graph,…

Combinatorics · Mathematics 2018-08-28 Shaofei Du , Klavdija Kutnar , Dragan Marusic

Given a surface with boundary and some points on its boundary, a polygon diagram is a way to connect those points as vertices of non-overlapping polygons on the surface. Such polygon diagrams represent non-crossing permutations on a surface…

Combinatorics · Mathematics 2019-09-27 Norman Do , Jian He , Daniel V. Mathews

We propose an algorithm for tracing polylines on a triangle mesh such that: they are aligned with a N-symmetry direction field, and two such polylines cannot cross or merge. This property is fundamental for mesh segmentation and is very…

Computational Geometry · Computer Science 2016-06-15 Nicolas Ray , Dmitry Sokolov

For two points in the closure of a simple polygon $P$, we say that they see each other in $P$ if the line segment uniting them does not intersect the exterior of $P$. The visibility graph of $P$ is the graph whose vertex set is the vertex…

Computational Geometry · Computer Science 2020-01-20 André C. Silva

We present CertifyHAM, an algorithm which takes as input a graph G and either finds a Hamilton cycle of G or it outputs that such a cycle does not exists. If G=G(n, p) and p >2000/n then the expected running time of CertifyHAM is O(n/p).…

Combinatorics · Mathematics 2022-10-18 Michael Anastos

A high-level description of an algorithm which computes the minimum perimeter triangle enclosing a convex polygon in linear time exists in the literature. Besides that an implementation of the algorithm is given in the subsequent work.…

Metric Geometry · Mathematics 2016-06-08 V. Ermolaev

A transparent rectangle visibility graph (TRVG) is a graph whose vertices can be represented by a collection of non-overlapping rectangles in the plane whose sides are parallel to the axes such that two vertices are adjacent if and only if…

Combinatorics · Mathematics 2025-06-18 Chaipattana Juntarapomdach , Teeradej Kittipassorn