Endpoint weighted estimate for a fixed finite-type curve

Establish the weighted Fourier extension inequality at the endpoint exponent \(\iota=\beta_{\max}(\Gamma)=(m_{\max}(\Gamma)+1)/(m_{\max}(\Gamma)+2)\) for a fixed finite-type convex planar curve \(\Gamma\), where \(m_{\max}(\Gamma)\) is the largest order of curvature vanishing attained on the curve.

Background

The paper proves that, for a fixed finite-type curve, the weighted estimate holds whenever ι>βmax(Γ)\iota>\beta_{\max}(\Gamma), while a counterexample rules it out whenever ι<βmax(Γ)\iota<\beta_{\max}(\Gamma). Thus only the endpoint remains unresolved. Resolving it would complete the sharp weighted-threshold theory for each fixed curve under consideration.

References

Thus, for a fixed curve, only the endpoint \iota=\beta_{\max}(\Gamma) remains open.

Normal-Direction Energy and Fourier Restriction for Convex Planar Curves  (2609.20643 - Vergara, 17 Sep 2026) in Theorem 1 (General direct theorem and weighted threshold), Introduction; see also the paragraph immediately following Proposition 4.5

The endpoint \iota=(k-1)/k remains open.

Normal-Direction Energy and Fourier Restriction for Convex Planar Curves  (2609.20643 - Vergara, 17 Sep 2026) in Introduction, subsection “The monomial model as an explicit case”; repeated at the end of Section 4.3