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Main Authors: Dudek, Andrzej, Grytczuk, Jarosław, Ruciński, Andrzej
Format: Preprint
Published: 2023
Subjects:
Online Access:https://arxiv.org/abs/2301.02936
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author Dudek, Andrzej
Grytczuk, Jarosław
Ruciński, Andrzej
author_facet Dudek, Andrzej
Grytczuk, Jarosław
Ruciński, Andrzej
contents For $r,n\ge2$, an ordered $r$-uniform matching of size $n$ is an $r$-uniform hypergraph on a linearly ordered vertex set $V$, with $|V|=rn$, consisting of $n$ pairwise disjoint edges. There are $\tfrac12\binom{2r}r$ different ways two edges may intertwine, called here patterns. Among them we identify $3^{r-1}$ collectable patterns $P$, which have the potential of appearing in arbitrarily large quantities called $P$-cliques. We prove an Erdős-Szekeres type result guaranteeing in every ordered $r$-uniform matching the presence of a $P$-clique of a prescribed size, for some collectable pattern $P$. In particular, in the diagonal case, one of the $P$-cliques must be of size $Ω\left( n^{3^{1-r}}\right)$. In addition, for each collectable pattern $P$ we show that the largest size of a $P$-clique in a random ordered $r$-uniform matching of size $n$ is, with high probability, $Θ\left(n^{1/r}\right)$.
format Preprint
id arxiv_https___arxiv_org_abs_2301_02936
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Erdős-Szekeres type Theorems for ordered uniform matchings
Dudek, Andrzej
Grytczuk, Jarosław
Ruciński, Andrzej
Combinatorics
For $r,n\ge2$, an ordered $r$-uniform matching of size $n$ is an $r$-uniform hypergraph on a linearly ordered vertex set $V$, with $|V|=rn$, consisting of $n$ pairwise disjoint edges. There are $\tfrac12\binom{2r}r$ different ways two edges may intertwine, called here patterns. Among them we identify $3^{r-1}$ collectable patterns $P$, which have the potential of appearing in arbitrarily large quantities called $P$-cliques. We prove an Erdős-Szekeres type result guaranteeing in every ordered $r$-uniform matching the presence of a $P$-clique of a prescribed size, for some collectable pattern $P$. In particular, in the diagonal case, one of the $P$-cliques must be of size $Ω\left( n^{3^{1-r}}\right)$. In addition, for each collectable pattern $P$ we show that the largest size of a $P$-clique in a random ordered $r$-uniform matching of size $n$ is, with high probability, $Θ\left(n^{1/r}\right)$.
title Erdős-Szekeres type Theorems for ordered uniform matchings
topic Combinatorics
url https://arxiv.org/abs/2301.02936