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We consider a variant of the art gallery problem where all guards are limited to seeing to the right inside a monotone polygon. We call such guards: half-guards. We provide a polynomial-time approximation for point guarding the entire…

Computational Geometry · Computer Science 2022-04-29 Hannah Miller Hillberg , Erik Krohn , Alex Pahlow

The art gallery problem enquires about the least number of guards sufficient to ensure that an art gallery, represented by a simple polygon $P$, is fully guarded. Most standard versions of this problem are known to be NP-hard. In 1987,…

Computational Geometry · Computer Science 2018-04-12 Pritam Bhattacharya , Subir Kumar Ghosh , Sudebkumar Pal

There exist many variants of guarding an orthogonal polygon in an orthogonal fashion: sometimes a guard can see an entire rectangle, or along a staircase, or along an orthogonal path with at most $k$ bends. In this paper, we study all these…

Computational Geometry · Computer Science 2017-06-08 Therese Biedl , Saeed Mehrabi

The problem of vertex guarding a simple polygon was first studied by Subir K. Ghosh (1987), who presented a polynomial-time $O(\log n)$-approximation algorithm for placing as few guards as possible at vertices of a simple $n$-gon $P$, such…

Computational Geometry · Computer Science 2019-07-03 Stav Ashur , Omrit Filtser , Matthew J. Katz

We are interested in the problem of guarding simple orthogonal polygons with the minimum number of $ r $-guards. The interior point $ p $ belongs an orthogonal polygon $ P $ is visible from $ r $-guard $ g $, if the minimum area rectangle…

Computational Geometry · Computer Science 2017-09-14 Hamid Hoorfar , Alireza Bagheri

One of the earliest and most well known problems in computational geometry is the so-called art gallery problem. The goal is to compute the minimum possible number guards placed on the vertices of a simple polygon in such a way that they…

Computational Geometry · Computer Science 2009-11-25 Menelaos I. Karavelas , Elias P. Tsigaridas

Guarding a polygon with few guards is an old and well-studied problem in computational geometry. Here we consider the following variant: We assume that the polygon is orthogonal and thin in some sense, and we consider a point $p$ to guard a…

Computational Geometry · Computer Science 2016-04-26 Therese Biedl , Saeed Mehrabi

The art gallery problem enquires about the least number of guards that are sufficient to ensure that an art gallery, represented by a polygon $P$, is fully guarded. In 1998, the problems of finding the minimum number of point guards, vertex…

Computational Geometry · Computer Science 2016-05-03 Pritam Bhattacharya , Subir Kumar Ghosh , Bodhayan Roy

We study the problem of colouring the vertices of a polygon, such that every viewer in it can see a unique colour. The goal is to minimise the number of colours used. This is also known as the conflict-free chromatic guarding problem with…

Computational Geometry · Computer Science 2020-04-07 Onur Çağırıcı , Subir Kumar Ghosh , Petr Hliněný , Bodhayan Roy

Terrain Guarding Problem(TGP), which is known to be NP-complete, asks to find a smallest set of guard locations on a terrain $T$ such that every point on $T$ is visible by a guard. Here, we study this problem on 1.5D orthogonal terrains…

Computational Geometry · Computer Science 2016-05-19 Yangdi Lyu , Alper Üngör

In this paper, we consider the 1.5-dimensional orthogonal terrain guarding problem. In this problem, we assign an x-monotone chain T because each edge is either horizontal or vertical, and determine the minimal number of vertex guards for…

Computational Geometry · Computer Science 2018-05-10 Wei-Yu Lai , Tien-Ruey Hsiang

Let an orthogonal polyhedron be the union of a finite set of boxes in $\mathbb R^3$ (i.e., cuboids with edges parallel to the coordinate axes), whose surface is a connected 2-manifold. We study the NP-complete problem of guarding a…

Computational Geometry · Computer Science 2019-10-25 Giovanni Viglietta

A sliding camera inside an orthogonal polygon $P$ is a point guard that travels back and forth along an orthogonal line segment $\gamma$ in $P$. The sliding camera $g$ can see a point $p$ in $P$ if the perpendicular from $p$ onto $\gamma$…

Computational Geometry · Computer Science 2016-04-26 Therese Biedl , Timothy M. Chan , Stephanie Lee , Saeed Mehrabi , Fabrizio Montecchiani , Hamideh Vosoughpour

We study the Dispersive Art Gallery Problem with vertex guards: Given a polygon $\mathcal{P}$, with pairwise geodesic Euclidean vertex distance of at least $1$, and a rational number $\ell$; decide whether there is a set of vertex guards…

Computational Geometry · Computer Science 2024-06-11 Sándor P. Fekete , Joseph S. B. Mitchell , Christian Rieck , Christian Scheffer , Christiane Schmidt

Given a simple polygon $\cal P$, in the Art Gallery problem the goal is to find the minimum number of guards needed to cover the entire $\cal P$, where a guard is a point and can see another point $q$ when $\overline{pq}$ does not cross the…

Computational Geometry · Computer Science 2021-12-03 Arash Vaezi , Mohammad Ghodsi

We investigate the Dispersive Art Gallery Problem with vertex guards and rectangular visibility ($r$-visibility) for a class of orthogonal polygons that reflect the properties of real-world floor plans: these office-like polygons consist of…

Computational Geometry · Computer Science 2025-06-27 Sándor P. Fekete , Kai Kobbe , Dominik Krupke , Joseph S. B. Mitchell , Christian Rieck , Christian Scheffer

We provide an O(log log OPT)-approximation algorithm for the problem of guarding a simple polygon with guards on the perimeter. We first design a polynomial-time algorithm for building epsilon-nets of size O(1/epsilon log log 1/epsilon) for…

Computational Geometry · Computer Science 2010-01-26 James King , David Kirkpatrick

We provide a spectrum of results for the Universal Guard Problem, in which one is to obtain a small set of points ("guards") that are "universal" in their ability to guard any of a set of possible polygonal domains in the plane. We give…

Computational Geometry · Computer Science 2017-03-28 Sándor P. Fekete , Qian Li , Joseph S. B. Mitchell , Christian Scheffer

In this paper we study the art gallery problem, which is one of the fundamental problems in computational geometry. The objective is to place a minimum number of guards inside a simple polygon such that the guards together can see the whole…

Computational Geometry · Computer Science 2017-01-20 Mikkel Abrahamsen , Anna Adamaszek , Tillmann Miltzow

We examine the Art Gallery Problem with Edge Guards. We present a heuristic algorithm to arrange edge guards to guard only the inward side of the walls of any N-vertex simple polygonal gallery using at most roof (N/4) edge guards - a…

Metric Geometry · Mathematics 2012-07-17 R. Nandakumar
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