Sharp thresholds for higher powers of Hamilton cycles in random graphs

Fuente: arXiv
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Autori principali: Makai, Tamás, Pasch, Matija, Petrova, Kalina, Schiller, Leon
Natura: Preprint
Pubblicazione: 2025
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author Makai, Tamás
Pasch, Matija
Petrova, Kalina
Schiller, Leon
author_facet Makai, Tamás
Pasch, Matija
Petrova, Kalina
Schiller, Leon
contents For $k \geq 4$, we establish that $p = (e/n)^{1/k}$ is a sharp threshold for the existence of the $k$-th power $H$ of a Hamilton cycle in the binomial random graph model. Our proof builds upon an approach by Riordan based on the second moment method, which previously established a weak threshold for $H$. This method expresses the second moment bound through contributions of subgraphs of $H$, with two key quantities: the number of copies of each subgraph in $H$ and the subgraphs' densities. We control these two quantities more precisely by carefully restructuring Riordan's proof and treating sparse and dense subgraphs of $H$ separately. This allows us to determine the exact constant in the threshold.
format Preprint
id arxiv_https___arxiv_org_abs_2502_14515
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Sharp thresholds for higher powers of Hamilton cycles in random graphs
Makai, Tamás
Pasch, Matija
Petrova, Kalina
Schiller, Leon
Combinatorics
05C80, 05D40
For $k \geq 4$, we establish that $p = (e/n)^{1/k}$ is a sharp threshold for the existence of the $k$-th power $H$ of a Hamilton cycle in the binomial random graph model. Our proof builds upon an approach by Riordan based on the second moment method, which previously established a weak threshold for $H$. This method expresses the second moment bound through contributions of subgraphs of $H$, with two key quantities: the number of copies of each subgraph in $H$ and the subgraphs' densities. We control these two quantities more precisely by carefully restructuring Riordan's proof and treating sparse and dense subgraphs of $H$ separately. This allows us to determine the exact constant in the threshold.
title Sharp thresholds for higher powers of Hamilton cycles in random graphs
topic Combinatorics
05C80, 05D40
url https://arxiv.org/abs/2502.14515