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In string theory, the $k$-th power of a string $w$ is named as $w^k$, where $w^0$ is the empty string $\epsilon$ and $w^n$ is the concatenation of $w$ and $w^{n - 1}$ $(n \in \mathbb{N}^{+})$.

The power in a string that mentioned below means some power which is one substring of the string. In addition, two strings are distinct if they don't look the same.

In Maxime Crochemore, et al. Number of Occurrences of powers in Strings, theorem 3 claims that "The number of distinct $k$-th powers, for a fixed integer $k \geq 3$, in a string of length $n$ is at most $\frac{n}{k-2}$".

If it is true, we may conclude the number of all distinct $k$-th powers for all integers $k \geq 3$ in a string of length $n$ is $\mathcal{O}(n \log n)$.

Is it possible to detect all these powers through some method in time complexity $\mathcal{O}(n \log n)$? For example, count the number of them and list one occurrence (start index and end index) for each of them.

I failed to seek results in recent research...

I asked the same question at here.

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  • $\begingroup$ Curiosity: where did the log* come from? $\endgroup$ Sep 4, 2018 at 23:28
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    $\begingroup$ This is probably better suited for cs.stackexchange.com (or perhaps cstheory.stackexchange.com — the two are a bit too similar for me to tell clearly). Note: if you do crosspost, remember to put back and forth links between the questions. $\endgroup$
    – Gro-Tsen
    Sep 5, 2018 at 7:46
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    $\begingroup$ What do you mean by "detect"? Count them or exhibit them or something else? If you want to exhibit them and there really are $n \log n$ of them, then you are not going to be able to do that in $O(n\log^* n)$. $\endgroup$
    – Aurel
    Sep 5, 2018 at 8:40
  • $\begingroup$ @StefanoGogioso Sorry, that's a mistake. :P $\endgroup$ Sep 5, 2018 at 14:14
  • $\begingroup$ "In addition, two strings are distinct if they don't look the same." To me, that makes it less clear, not more, what 'distinct' means …. $\endgroup$
    – LSpice
    Sep 5, 2018 at 14:14

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