The Nesting Bird Box Problem is ER-complete: Sharp Hardness Results for the Hidden Set Problem

Fuente: arXiv
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Main Authors: Meijer, Lucas, Miltzow, Till, Ockenfels, Johanna, Stojaković, Miloš
Format: Preprint
Published: 2026
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_version_ 1866918499335536640
author Meijer, Lucas
Miltzow, Till
Ockenfels, Johanna
Stojaković, Miloš
author_facet Meijer, Lucas
Miltzow, Till
Ockenfels, Johanna
Stojaković, Miloš
contents In the (Nesting) Bird Box Problem we are given a polygonal domain P and a number k and we want to know if there is a set B of k points inside P such that no two points in B can see each other. The underlying idea is that each point represents a birdhouse and many birds only use a birdhouse if there is no other occupied birdhouse in its vicinity. We say two points a,b see each other if the open segment ab intersects neither the exterior of P nor any vertex of P. We show that the Nesting Bird Box problem is ER-complete. The complexity class ER can be defined by the set of problems that are polynomial time equivalent to finding a solution to the equation $p(x) = 0$, with $x\in R^n$ and $p\in $Z[X_1,...,X_n]$. The proof builds on the techniques developed in the original ER-completeness proof of the Art Gallery problem. However our proof is significantly shorter for two reasons. First, we can use recently developed tools that were not available at the time. Second, we consider polygonal domains with holes instead of simple polygons.
format Preprint
id arxiv_https___arxiv_org_abs_2604_26749
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The Nesting Bird Box Problem is ER-complete: Sharp Hardness Results for the Hidden Set Problem
Meijer, Lucas
Miltzow, Till
Ockenfels, Johanna
Stojaković, Miloš
Computational Geometry
68Q17
In the (Nesting) Bird Box Problem we are given a polygonal domain P and a number k and we want to know if there is a set B of k points inside P such that no two points in B can see each other. The underlying idea is that each point represents a birdhouse and many birds only use a birdhouse if there is no other occupied birdhouse in its vicinity. We say two points a,b see each other if the open segment ab intersects neither the exterior of P nor any vertex of P. We show that the Nesting Bird Box problem is ER-complete. The complexity class ER can be defined by the set of problems that are polynomial time equivalent to finding a solution to the equation $p(x) = 0$, with $x\in R^n$ and $p\in $Z[X_1,...,X_n]$. The proof builds on the techniques developed in the original ER-completeness proof of the Art Gallery problem. However our proof is significantly shorter for two reasons. First, we can use recently developed tools that were not available at the time. Second, we consider polygonal domains with holes instead of simple polygons.
title The Nesting Bird Box Problem is ER-complete: Sharp Hardness Results for the Hidden Set Problem
topic Computational Geometry
68Q17
url https://arxiv.org/abs/2604.26749