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arXiv · 2309.12666

Diophantine estimates on shifts of trigonometric polynomials on $\mathbb{T}^d$

Yunfeng Shi·W. -M. Wang
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Abstract

We establish Diophantine type estimates on shifts of trigonometric polynomials on the torus $\mathbb{T}^d$, as well as that of their square roots. These estimates arise from the spectral analysis of the quasi-periodic Schr\"odinger and the quasi-periodic wave operators. They have applications to the nonlinear quasi-periodic Schr\"odinger equations (NLS) and the nonlinear quasi-periodic wave equations (NLW). One could now, for example, extend the result of Bourgain (Geom. Funct. Anal. 17(3): 682-706, 2007) to the nonlinear setting.

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Yunfeng Shi, W. -M. Wang. 2023-09-22. Diophantine estimates on shifts of trigonometric polynomials on $\mathbb{T}^d$. https://arxiv.org/abs/2309.12666

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