Velani's conjecture for dyadic approximation on the middle-third Cantor set

Let CC be the middle-third Cantor set and let

be its Cantor\Lebesgue measure. For a function $:\to[0,\infty)$, define

W_2:=\left{x\in[0,1]: |2^nx|<(n)\text{ for infinitely many }n\in\right}.

Velanisconjecture.If**Velani's conjecture.** If

is monotonic, then

(W2)={0if n=1(n)<,1if n=1(n)=.(W_2)=\begin{cases}0&\text{if }\sum_{n=1}^{\infty}(n)<\infty,\\1&\text{if }\sum_{n=1}^{\infty}(n)=\infty.\end{cases}

This is a Khintchine-type zero\one law for dyadic shrinking targets on the Cantor set. The conjecture is widely open; existing results establish only restricted convergence and divergence cases.

Sources & referencesView supporting material

Primary source

Xin-Rong Dai, Bing Li, Bo Wang and Yu-Feng Wu, “Metric results for dyadic approximation on the middle-third Cantor set”, arXiv:2606.25305 (2026).

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