Boundary area rigidity conjecture under positive Ricci curvature

Let MnM^n be a compact Riemannian manifold with boundary Σ=M\Sigma=\partial M, Ricn1Ric\geq n-1, and second fundamental form Π0\Pi\geq 0. Boundary area rigidity conjecture.

ΣSn1.|\Sigma|\leq |\mathbb{S}^{n-1}|.

Moreover, equality should imply that (Mn,g)(M^n,g) is isometric to the hemisphere

S+n=xRn+1:x=1,xn+10Rn+1.\mathbb{S}^n_+=\\{x\in\mathbb{R}^{n+1}:|x|=1,\\ x_{n+1}\geq 0\\}\subset\mathbb{R}^{n+1}.

The statement is proposed as a sharp area bound with rigidity in the positive-Ricci setting; the supplied text gives no resolution.

Sources & referencesView supporting material

Primary source

Xiaodong Wang, “On compact Riemannian manifolds with convex boundary and Ricci curvature bounded from below”, arXiv:1908.03069 (2020).

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