The arc chromatic number for Galois projective planes, affine planes and Euclidean grids

Fuente: arXiv
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Auteurs principaux: Araujo-Pardo, Gabriela, Martínez-Sandoval, Leonardo
Format: Preprint
Publié: 2026
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author Araujo-Pardo, Gabriela
Martínez-Sandoval, Leonardo
author_facet Araujo-Pardo, Gabriela
Martínez-Sandoval, Leonardo
contents We establish that the minimum number of arcs required to partition the Galois projective plane $\text{PG}(2,q)$ is $q+1$. Furthermore, we determine the exact value for a fractional variant of this problem. We extend our analysis to affine planes $\text{AG}(2,q)$, proving that they can be partitioned into $q$ arcs. In particular, we show that this partition is tight when $q$ is an odd prime power, and that a $(q-1)$-partition is attainable for $q=2^k$ with $k \in \{1,2,3\}$. For $q=2^k$ with $k \geq 4$, we provide bounds between two possible values. Finally, we apply these results to Euclidean grids, demonstrating that a partition into $(1+ε)n$ sets in general position exists for any $ε> 0$ and sufficiently large $n$. We also present exact minimal partitions for small Euclidean grids.
format Preprint
id arxiv_https___arxiv_org_abs_2601_19043
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The arc chromatic number for Galois projective planes, affine planes and Euclidean grids
Araujo-Pardo, Gabriela
Martínez-Sandoval, Leonardo
Combinatorics
Discrete Mathematics
05B25, 51E15, 51E21, 05C15, 68V05
We establish that the minimum number of arcs required to partition the Galois projective plane $\text{PG}(2,q)$ is $q+1$. Furthermore, we determine the exact value for a fractional variant of this problem. We extend our analysis to affine planes $\text{AG}(2,q)$, proving that they can be partitioned into $q$ arcs. In particular, we show that this partition is tight when $q$ is an odd prime power, and that a $(q-1)$-partition is attainable for $q=2^k$ with $k \in \{1,2,3\}$. For $q=2^k$ with $k \geq 4$, we provide bounds between two possible values. Finally, we apply these results to Euclidean grids, demonstrating that a partition into $(1+ε)n$ sets in general position exists for any $ε> 0$ and sufficiently large $n$. We also present exact minimal partitions for small Euclidean grids.
title The arc chromatic number for Galois projective planes, affine planes and Euclidean grids
topic Combinatorics
Discrete Mathematics
05B25, 51E15, 51E21, 05C15, 68V05
url https://arxiv.org/abs/2601.19043