Local restriction conjecture for the normalized extension operator

Let Φ:Bn1(0,1)R\Phi:B^{n-1}(0,1)\to\mathbb{R} satisfy Φ(0)=0\Phi(0)=0, Φ(0)=0\nabla\Phi(0)=0, and have Hessian eigenvalues comparable to 11. Define

Ef(x):=Bn1(0,1)eixˉξˉeixnΦ(ξˉ)f(ξ)dξ.Ef(x):=\int_{B^{n-1}(0,1)}e^{i\bar{x}\cdot\bar{\xi}}e^{ix_n\Phi(\bar{\xi})}f(\xi)\,d\xi.

Normalized local restriction conjecture. If p2nn1p\geq\frac{2n}{n-1}, then for every ε>0\varepsilon>0 and R>1R>1,

EfLp(BR)CεRεfp.\|Ef\|_{L^p(B_R)}\leq C_\varepsilon R^\varepsilon\|f\|_p.

The paper states this as equivalent to the preceding local restriction formulation after normalizing the hypersurface and replacing surface measure by a smooth density; it remains open in general.

Sources & referencesView supporting material

Primary source

Hong Wang and Shukun Wu, “Restriction estimates using decoupling theorems and two-ends Furstenberg inequalities”, arXiv:2411.08871 (2024).

Additional references

3 papers in this index state this conjecture (2023–2024). The statement above is taken from the most recent of them; the others are arXiv:2407.08549, arXiv:2312.08633.

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