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arXiv 1702.07698math.DS
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正熵无穷序列的复杂度和分形维数

Complexity and fractal dimensions for infinite sequences with positive entropy

Carlos Gustavo Moreira, Christian Mauduit

摘要:

有限字母表$A$上的无限字$w$的复杂度函数是序列计数,对于每个非负$n$,字母表$A$上长度为$n$的字的数量是无限字$w$的因子。这项工作的目标是估计字母表$A$上的长度$n$的字的数量,这些字是无限字$w$的因子,其复杂度函数由具有指数增长性的给定函数$f$限定,并且描述这样的无限字集合的组合结构。我们引入了一个实参数,{ \it字熵} $E_W(f)$与一个给定的功能$f$和我们确定的集的分形维数的无穷序列的复杂性函数的范围内的$f$的字熵。我们提出了一个组合证明的事实,即$E_W(f)$等于拓扑熵的子移位的无限的话,其复杂性是有界的$f$,我们给出了几个例子表明,即使在强条件下的$f$,字熵$E_W(f)$可以严格小于限制较低的指数增长性率的$f$。

英文摘要:

The complexity function of an infinite word $w$ on a finite alphabet $A$ is the sequence counting, for each non-negative $n$, the number of words of length $n$ on the alphabet $A$ that are factors of the infinite word $w$. The goal of this work is to estimate the number of words of length $n$ on the alphabet $A$ that are factors of an infinite word $w$ with a complexity function bounded by a given function $f$ with exponential growth and to describe the combinatorial structure of such sets of infinite words. We introduce a real parameter, the {\it word entropy} $E_W(f)$ associated to a given function $f$ and we determine the fractal dimensions of sets of infinite sequences with complexity function bounded by $f$ in terms of its word entropy. We present a combinatorial proof of the fact that $E_W(f)$ is equal to the topological entropy of the subshift of infinite words whose complexity is bounded by $f$ and we give several examples showing that even under strong conditions on $f$, the word entropy $E_W(f)$ can be strictly smaller than the limiting lower exponential growth rate of $f$.

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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