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Main Authors: Shpectorov, Sergey, Zhao, Tianxiao
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2504.02449
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author Shpectorov, Sergey
Zhao, Tianxiao
author_facet Shpectorov, Sergey
Zhao, Tianxiao
contents We investigate the second smallest unresolved feasible set of parameters of strongly regular graphs, $(v,k,λ,μ)=(85,14,3,2)$. Using the classification of cubic graphs of small degree, we restrict possible local structure of such a graph $G$. After that, we exhaustively enumerate possible neighbourhoods of a maximal $3$-clique of $G$ and check them against a variety of conditions, including the combinatorial ones, coming from $λ=3$ and $μ=2$, as well as the linear algebra ones, utilising the Euclidean representation of $G$. These conditions yield contradiction in all cases, and hence, no $\mathrm{srg}(85,14,3,2)$ exists.
format Preprint
id arxiv_https___arxiv_org_abs_2504_02449
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Strongly regular graphs with parameters (85,14,3,2) do not exist
Shpectorov, Sergey
Zhao, Tianxiao
Combinatorics
05E30
We investigate the second smallest unresolved feasible set of parameters of strongly regular graphs, $(v,k,λ,μ)=(85,14,3,2)$. Using the classification of cubic graphs of small degree, we restrict possible local structure of such a graph $G$. After that, we exhaustively enumerate possible neighbourhoods of a maximal $3$-clique of $G$ and check them against a variety of conditions, including the combinatorial ones, coming from $λ=3$ and $μ=2$, as well as the linear algebra ones, utilising the Euclidean representation of $G$. These conditions yield contradiction in all cases, and hence, no $\mathrm{srg}(85,14,3,2)$ exists.
title Strongly regular graphs with parameters (85,14,3,2) do not exist
topic Combinatorics
05E30
url https://arxiv.org/abs/2504.02449