Counting Unions of Schreier Sets

Fuente: arXiv
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Main Authors: Beanland, Kevin, Gorovoy, Dmitriy, Hodor, Jȩdrzej, Homza, Daniil
Format: Preprint
Published: 2022
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author Beanland, Kevin
Gorovoy, Dmitriy
Hodor, Jȩdrzej
Homza, Daniil
author_facet Beanland, Kevin
Gorovoy, Dmitriy
Hodor, Jȩdrzej
Homza, Daniil
contents A subset of positive integers $F$ is a Schreier set if it is non-empty and $|F|\leqslant \min F$ (here $|F|$ is the cardinality of $F$). For each positive integer $k$, we define $k\mathcal{S}$ as the collection of all the unions of at most $k$ Schreier sets. Also, for each positive integer $n$, let $(k\mathcal{S})^n$ be the collection of all sets in $k\mathcal{S}$ with the maximum element equal to $n$. It is well-known that the sequence $(|(1\mathcal{S})^n|)_{n=1}^\infty$ is the Fibbonacci sequence. In particular, the sequence satisfies a linear recurrence. We generalize this statement, namely, we show that the sequence $(|(k\mathcal{S})^n|)_{n=1}^\infty$ satisfies a linear recurrence for every positive $k$.
format Preprint
id arxiv_https___arxiv_org_abs_2211_01049
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Counting Unions of Schreier Sets
Beanland, Kevin
Gorovoy, Dmitriy
Hodor, Jȩdrzej
Homza, Daniil
Combinatorics
05A19
A subset of positive integers $F$ is a Schreier set if it is non-empty and $|F|\leqslant \min F$ (here $|F|$ is the cardinality of $F$). For each positive integer $k$, we define $k\mathcal{S}$ as the collection of all the unions of at most $k$ Schreier sets. Also, for each positive integer $n$, let $(k\mathcal{S})^n$ be the collection of all sets in $k\mathcal{S}$ with the maximum element equal to $n$. It is well-known that the sequence $(|(1\mathcal{S})^n|)_{n=1}^\infty$ is the Fibbonacci sequence. In particular, the sequence satisfies a linear recurrence. We generalize this statement, namely, we show that the sequence $(|(k\mathcal{S})^n|)_{n=1}^\infty$ satisfies a linear recurrence for every positive $k$.
title Counting Unions of Schreier Sets
topic Combinatorics
05A19
url https://arxiv.org/abs/2211.01049