arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2602.16152math.COcs.DMcs.FL
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斐波那契和周期倍增词的最小字符串吸引子

The Smallest String Attractors of Fibonacci, Period-Doubling, and Thue--Morse Words

Graduate School of Informatics, Nagoya University(名古屋大学情报大学院);M&D Data Science Center, Institute of Science Tokyo(东京科学大学M&D数据科学中心);Department of Computer Science and Engineering, University of Yamanashi(山梨大学计算机科学与工程系);Graduate School of Informatics and Engineering, University of Electro-Communications(电波大学信息与工程学研究生院)

Mutsunori Banbara, Hideo Bannai, Peaker Guo, Dominik Köppl, Takuya Mieno, Yoshio Okamoto

AI总结:

研究斐波那契和周期倍增词的最小字符串吸引子的结构和数量,揭示其在相同大小下的差异。

摘要:

一个字符串T[1..|T|]的字符串吸引子是一个位置集合Γ,使得任何子字符串w在T中都有一个出现跨越Γ中的位置,即存在一个位置i,使得w=T[i..i+|w|-1],并且区间[i,i+|w|-1]与Γ的交集非空。已知斐波那契词的最小字符串吸引子的大小为2。我们完全刻画了所有最小字符串吸引子的集合,并展示了一个递归公式,描述了第n个斐波那契词的最小字符串吸引子的2^{n-4} + 2^{⌈n/2⌉ - 2}个不同的位置对,其中n≥7。同样,周期倍增词的最小字符串吸引子的大小已知为2。我们还完全刻画了所有最小字符串吸引子的集合,并展示了一个公式,描述了第n个周期倍增词的最小字符串吸引子的两个不同的位置对,其中n≥2。我们的结果表明,具有相同最小吸引子大小的字符串可以有截然不同的不同最小吸引子数量。

英文摘要:

A string attractor of a string $T[1..|T|]$ is a set of positions $Γ$ of $T$ such that any nonempty substring $w$ of $T$ has an occurrence that crosses a position in $Γ$, i.e., there is a position $i$ such that $w = T[i..i+|w|-1]$ and the intersection $[i,i+|w|-1]\cap Γ$ is nonempty. The size of the smallest string attractor of Fibonacci words and period-doubling words of length at least $2$ is known to be $2$. The size of the smallest string attractor of Thue--Morse words of length at least $25$ is known to be $4$. We completely characterize the set of all smallest string attractors of Fibonacci words, period-doubling words, and Thue--Morse words. For Fibonacci words, we show a recursive formula describing the $2^{n-4} + 2^{\lceil n/2 \rceil - 2}$ distinct position pairs that are the smallest string attractors of the $n$th Fibonacci word for $n \geq 7$. For period-doubling words, we show that the $n$th period-doubling word has exactly two smallest string attractors for every $n\geq 2$, and give them explicitly. For Thue--Morse words, we show a formula describing the 32 sets of four positions that are the smallest string attractors of the $n$th Thue--Morse word for $n\geq 6$. Our results show that strings with the same smallest attractor size can have a drastically different number of distinct smallest attractors.

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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