1 results
Grid method for divergence of averages
- Part of
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- Journal:
- Ergodic Theory and Dynamical Systems / Volume 44 / Issue 2 / February 2024
- Published online by Cambridge University Press:
- 11 April 2023, pp. 646-664
- Print publication:
- February 2024
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- Article
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In this paper, we will introduce the ‘grid method’ to prove that the extreme case of oscillation occurs for the averages obtained by sampling a flow along the sequence of times of the form
$\{n^\alpha : n\in {\mathbb {N}}\}$, where 
$\alpha $ is a positive non-integer rational number. Such behavior of a sequence is known as the strong sweeping-out property. By using the same method, we will give an example of a general class of sequences which satisfy the strong sweeping-out property. This class of sequences may be useful to solve a long-standing open problem: for a given irrational 
$\alpha $, whether the sequence 
$(n^\alpha )$ is bad for pointwise ergodic theorem in 
$L^2$ or not. In the process of proving this result, we will also prove a continuous version of the Conze principle.
