The Erdős unit distance problem for small point sets

Fuente: arXiv
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Autori principali: Alexeev, Boris, Mixon, Dustin G., Parshall, Hans
Natura: Preprint
Pubblicazione: 2024
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author Alexeev, Boris
Mixon, Dustin G.
Parshall, Hans
author_facet Alexeev, Boris
Mixon, Dustin G.
Parshall, Hans
contents We improve the best known upper bound on the number of edges in a unit-distance graph on $n$ vertices for each $n\in\{16,\ldots,30\}$. When $n\leq 21$, our bounds match the best known lower bounds, and we fully enumerate the densest unit-distance graphs in these cases. On the combinatorial side, our principle technique is to more efficiently generate $\mathcal{F}$-free graphs for a set of forbidden subgraphs $\mathcal{F}$. On the algebraic side, we are able to determine programmatically whether many graphs are unit-distance, using a custom embedder that is more efficient in practice than tools such as cylindrical algebraic decomposition.
format Preprint
id arxiv_https___arxiv_org_abs_2412_11914
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Erdős unit distance problem for small point sets
Alexeev, Boris
Mixon, Dustin G.
Parshall, Hans
Combinatorics
Metric Geometry
We improve the best known upper bound on the number of edges in a unit-distance graph on $n$ vertices for each $n\in\{16,\ldots,30\}$. When $n\leq 21$, our bounds match the best known lower bounds, and we fully enumerate the densest unit-distance graphs in these cases. On the combinatorial side, our principle technique is to more efficiently generate $\mathcal{F}$-free graphs for a set of forbidden subgraphs $\mathcal{F}$. On the algebraic side, we are able to determine programmatically whether many graphs are unit-distance, using a custom embedder that is more efficient in practice than tools such as cylindrical algebraic decomposition.
title The Erdős unit distance problem for small point sets
topic Combinatorics
Metric Geometry
url https://arxiv.org/abs/2412.11914