Choi–Wang–Reilly boundary eigenvalue conjecture and Hui-Hsien Wang boundary-area conjecture

For every integer n≥2n\ge 2, if (Mn+1,g)(M^{n+1},g) is a compact Riemannian manifold with boundary satisfying Ric⁡g≥ng\operatorname{Ric}_g\ge n g and II⁡g≥0\operatorname{II}_g\ge 0 on ∂M\partial M, then the first nonzero Laplace eigenvalue of the induced boundary metric satisfies λ1(∂M,g∣∂M)≥n\lambda_1(\partial M,g|_{\partial M})\ge n.

References

Progress summary

Refreshed
Claimed progress

A recent paper claims the eigenvalue conjecture is false in three or more dimensions, while the boundary-area conjecture has only an infinitesimal obstruction so far.

The problem concerns a proposed sharp boundary eigenvalue bound and a related boundary-area inequality for geometric spaces with boundary. No proposer or date is identified in the retrieved material.

Known results

  • A December 2015 paper constructed, for every n≥2n\geq 2, positively Ricci-curved hemispheres with minimal boundary and first boundary eigenvalue λ1<n\lambda_1<n, giving a boundary counterexample to the relevant Choi–Wang conjecture.
  • The same work established a first-variation rigidity statement: under technical hypotheses fixing Ricci curvature and boundary mean curvature to first order, the first boundary eigenvalue has zero first variation.
  • A later result extended a theorem of Choi and Wang to nonminimal hypersurfaces, without resolving either conjecture.

August 26, 2026 claimed counterexample and area obstruction

A paper titled Conformal Boundary Deformations under Ricci Lower Bounds: Eigenvalue Counterexamples and Area Obstructions claims that the proposed eigenvalue bound fails in every dimension at least three, even for metrics arbitrarily close to the round hemisphere. It also claims a first-variation obstruction to a conformal boundary-area conjecture, not a full counterexample; both claims remain unverified.

Current status (as of August 2026): The eigenvalue strengthening is claimed false in dimensions n≥3n\geq 3, while the boundary-area conjecture remains unresolved beyond an unverified infinitesimal obstruction.

Sources

Solutions 0

No solutions have been posted yet.