arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2009.03475math.CO
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正交频率平方极大集

Maximal sets of mutually orthogonal frequency squares

Nicholas J. Cavenagh, Adam Mammoliti, Ian M. Wanless

摘要:

频率方阵是一个方阵,其中每一行和每一列都是相同的多组符号的排列。如果频率平方包含$n/λ$符号,则其为$(n;λ)$类型,其中每个符号每行出现$λ$次,每列出现$λ$次。在$λ=n/2$的情况下,我们将频率平方称为二进制。一组$k$ -MOFS $(n;λ)$是一组$(n;λ)$类型的$k$频率平方,使得当任何两个频率平方叠加时,每个可能的有序对出现的频率相等。$k$ -maxMOFS $(n;λ)$的集合是不包含在任何$(k+1)$-MOFS $(n;λ)$的集合中的$k$-MOFS $(n;λ)$的集合.对于偶数$n$,令$μ(n)$是最小的$k$,使得存在一组$k$ -maxMOFS $(n;n/2)$。它显示在[电子。J。27(3)(2020),P3.7],如果$n/2$是奇数,则为$μ(n)=1$,如果$n/2$是偶数,则为$μ(n)>1$。推广这一结果,我们表明,如果$n/2$是偶数,那么$μ(n)>2$。此外,我们表明,只要$n$是可分的$k$的一个特定的功能,不存在一组$k'$ -最大MOFS $(n;n/2)$的任何$k'\le k$。特别地,这意味着$\limsup μ(n)$是无界的。然而,我们可以构造无限族的极大二元MOFS的固定基数。更一般地,令$q=p^u$为素数幂,令$p^v$为除$n$的$p$的最高幂。如果$0\le v-uh<u/2$为$h\ge1$,则我们证明存在一组$(q^h-1)^2/(q-1)$ -maxMOFS $(n;n/q)$。

英文摘要:

A frequency square is a square matrix in which each row and column is a permutation of the same multiset of symbols. A frequency square is of type $(n;λ)$ if it contains $n/λ$ symbols, each of which occurs $λ$ times per row and $λ$ times per column. In the case when $λ=n/2$ we refer to the frequency square as binary. A set of $k$-MOFS$(n;λ)$ is a set of $k$ frequency squares of type $(n;λ)$ such that when any two of the frequency squares are superimposed, each possible ordered pair occurs equally often. A set of $k$-maxMOFS$(n;λ)$ is a set of $k$-MOFS$(n;λ)$ that is not contained in any set of $(k+1)$-MOFS$(n;λ)$. For even $n$, let $μ(n)$ be the smallest $k$ such that there exists a set of $k$-maxMOFS$(n;n/2)$. It was shown in [Electron. J. Combin. 27(3) (2020), P3.7] that $μ(n)=1$ if $n/2$ is odd and $μ(n)>1$ if $n/2$ is even. Extending this result, we show that if $n/2$ is even, then $μ(n)>2$. Also, we show that whenever $n$ is divisible by a particular function of $k$, there does not exist a set of $k'$-maxMOFS$(n;n/2)$ for any $k'\le k$. In particular, this means that $\limsup μ(n)$ is unbounded. Nevertheless we can construct infinite families of maximal binary MOFS of fixed cardinality. More generally, let $q=p^u$ be a prime power and let $p^v$ be the highest power of $p$ that divides $n$. If $0\le v-uh<u/2$ for $h\ge1$ then we show that there exists a set of $(q^h-1)^2/(q-1)$-maxMOFS$(n;n/q)$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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