Discrete Fourier restriction conjecture for the monomial curve

Let d3d\geq 3 be an integer, let NNN\in\mathbb N, let a1,,aNCa_1,\ldots,a_N\in\mathbb C, and write T2\mathbb T^2 for the two-dimensional torus. For p2(d+1)p\geq 2(d+1) and every ε>0\varepsilon>0, the discrete Fourier restriction conjecture asserts that

n=1Nane2πix1n+2πix2ndLp(T2)Nε(n=1Nan2)12.\left\|\sum_{n=1}^N a_n e^{2\pi i x_1 n+2\pi i x_2 n^d}\right\|_{L^p(\mathbb T^2)}\lesssim N^\varepsilon\left(\sum_{n=1}^N|a_n|^2\right)^{\frac12}.

This is a mean-value estimate for exponential sums on the discrete curve (n,nd)(n,n^d) and is of interest in additive number theory because it would yield a substantial improvement in Waring's problem. It is also a discrete Fourier restriction problem; the source does not state whether the conjecture has been resolved.

Sources & referencesView supporting material

Primary source

Xiaochun Li, “A Stein-Tomas type estimate and a decoupling inequality”, arXiv:2309.12835 (2023).

Additional references

2 papers in this index state this conjecture (2013–2023). The statement above is taken from the most recent of them; the others are arXiv:1310.5244.

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