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We resolve the complexity of the point-boundary variant of the art gallery problem, showing that it is $\exists\mathbb{R}$-complete, meaning that it is equivalent under polynomial time reductions to deciding whether a system of polynomial…

Computational Geometry · Computer Science 2025-04-11 Jack Stade

Given a closed simple polygon $P$, we say two points $p,q$ see each other if the segment $pq$ is fully contained in $P$. The art gallery problem seeks a minimum size set $G\subset P$ of guards that sees $P$ completely. The only currently…

Computational Geometry · Computer Science 2024-08-07 Simon Hengeveld , Tillmann Miltzow

We devise an algorithm for surveying a dynamic orthogonal polygonal domain by placing one guard at each vertex in a subset of its vertices, i.e., whenever an orthogonal polygonal domain {\cal P'} is modified to result in another orthogonal…

Computational Geometry · Computer Science 2021-11-15 Debangshu Banerjee , R. Inkulu

Given a simple polygon $\mathcal{P}$ on $n$ vertices, two points $x,y$ in $\mathcal{P}$ are said to be visible to each other if the line segment between $x$ and $y$ is contained in $\mathcal{P}$. The Point Guard Art Gallery problem asks for…

Computational Geometry · Computer Science 2016-07-20 Édouard Bonnet , Tillmann Miltzow

Given a simple polygon $\mathcal{P}$ on $n$ vertices, two points $x,y$ in $\mathcal{P}$ are said to be visible to each other if the line segment between $x$ and $y$ is contained in $\mathcal{P}$. The Point Guard Art Gallery problem asks for…

Computational Geometry · Computer Science 2020-06-23 Édouard Bonnet , Tillmann Miltzow

In the art gallery problem, we are given a closed polygon $P$, with rational coordinates and an integer $k$. We are asked whether it is possible to find a set (of guards) $G$ of size $k$ such that any point $p\in P$ is seen by a point in…

Computational Geometry · Computer Science 2026-03-18 Lucas Meijer , Tillmann Miltzow

In this paper, we study the Contiguous Art Gallery Problem, introduced by Thomas C. Shermer at the 2024 Canadian Conference on Computational Geometry, a variant of the classical art gallery problem from 1973 by Victor Klee. In the…

Computational Geometry · Computer Science 2025-06-30 Magnus Christian Ring Merrild , Casper Moldrup Rysgaard , Jens Kristian Refsgaard Schou , Rolf Svenning

We prove that the art gallery problem is equivalent under polynomial time reductions to deciding whether a system of polynomial equations over the real numbers has a solution. The art gallery problem is a classical problem in computational…

Computational Geometry · Computer Science 2018-05-10 Mikkel Abrahamsen , Anna Adamaszek , Tillmann Miltzow

We introduce a new variant of the art gallery problem that comes from safety issues. In this variant we are not interested in guard sets of smallest cardinality, but in guard sets with largest possible distances between these guards. To the…

Computational Geometry · Computer Science 2023-09-11 Christian Rieck , Christian Scheffer

The boundary-boundary art-gallery problem asks, given a polygon $P$ representing an art-gallery, for a minimal set of guards that can see the entire boundary of $P$ (the wall of the art gallery), where the guards must be placed on the…

Computational Geometry · Computer Science 2026-03-13 Jack Stade

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

In the Art Gallery Problem we are given a polygon $P\subset [0,L]^2$ on $n$ vertices and a number $k$. We want to find a guard set $G$ of size $k$, such that each point in $P$ is seen by a guard in $G$. Formally, a guard $g$ sees a point $p…

Computational Geometry · Computer Science 2018-11-06 Michael Gene Dobbins , Andreas Holmsen , Tillmann Miltzow

The Art Gallery Problem (AGP) is one of the classical problems in computational geometry. It asks for the minimum number of guards required to achieve visibility coverage of a given polygon. The AGP is well-known to be NP-hard even in…

This paper focuses on a variation of the Art Gallery problem that considers open edge guards and open mobile guards. A mobile guard can be placed on edges and diagonals of a polygon, and the "open" prefix means that the endpoints of such…

Computational Geometry · Computer Science 2013-06-20 Antonio Leslie Bajuelos , Santiago Canales , Gregorio Hernández , Mafalda Martins , Inês Matos

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

Let $G$ be a graph with $n$ vertices, $m$ edges, average degree $\delta$, and maximum degree $\Delta$. The "oriented chromatic number" of $G$ is the maximum, taken over all orientations of $G$, of the minimum number of colours in a proper…

Combinatorics · Mathematics 2008-09-09 David R. Wood

The Art Gallery Problem (AGP) asks for placing a minimum number of stationary guards in a polygonal region P, such that all points in P are guarded. The problem is known to be NP-hard, and its inherent continuous structure (with both the…

Computational Geometry · Computer Science 2014-12-19 Sándor P. Fekete , Stephan Friedrichs , Alexander Kröller , Christiane Schmidt

A terrain is an x-monotone polygonal curve, i.e., successive vertices have increasing x-coordinates. Terrain Guarding can be seen as a special case of the famous art gallery problem where one has to place at most $k$ guards on a terrain…

Computational Geometry · Computer Science 2018-07-03 Édouard Bonnet , Panos Giannopoulos

This paper addresses the problem of tracking mobile intruders in a polygonal environment. We assume that a team of diagonal guards is deployed inside the polygon to provide mobile coverage. First, we formulate the problem of tracking a…

Computational Geometry · Computer Science 2018-07-24 Guillermo J. Laguna , Sourabh Bhattacharya

We prove that every simply connected orthogonal polygon of $n$ vertices can be partitioned into $\left\lfloor\frac{3 n +4}{16}\right\rfloor$ (simply connected) orthogonal polygons of at most 8 vertices. It yields a new and shorter proof of…

Combinatorics · Mathematics 2017-06-27 Ervin Győri , Tamás Róbert Mezei