Bilinear space-time estimate conjecture

Let N>0N>0, let e1e_1 be the first coordinate vector, and suppose that the Fourier transforms f1^\widehat{f_1} and f2^\widehat{f_2} are supported on subsets of Bn(Ne1,1)\mathbb{B}^n(Ne_1,1) such that

dist(suppf1^,suppf2^)12.\operatorname{dist}(\operatorname{supp}\widehat{f_1},\operatorname{supp}\widehat{f_2})\geq\frac{1}{2}.

Bilinear space-time estimate conjecture. For 2p,r<2\leq p,r<\infty, the estimate

eitΔf1eitΔf21/2LxpLtr(Rn+1)Cp,rN1p1rf1L21/2f2L21/2\left\||e^{it\Delta}f_1e^{it\Delta}f_2|^{1/2}\right\|_{L_x^pL_t^r(\mathbb{R}^{n+1})}\leq C_{p,r}N^{\frac{1}{p}-\frac{1}{r}}\|f_1\|_{L^2}^{1/2}\|f_2\|_{L^2}^{1/2}

holds if and only if

n+2p+1rn+12.\frac{n+2}{p}+\frac{1}{r}\leq\frac{n+1}{2}.

This conjecture is formulated because it implies the paper's preceding space-time conjecture. The source does not report a resolution, so the estimate remains open in the stated range.

Sources & referencesView supporting material

Primary source

Junfeng Li, Changxing Miao and Ankang Yu, “The space-time estimates for the Schrödinger equation”, arXiv:2402.13539 (2024).

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