Small tree-foliation conjecture for positively curved Riemannian 3-spheres

From papers

Let (S3,g)(S^3,g) be a Riemannian 3-sphere with scalar curvature RgΛ0>0R_g\geq \Lambda_0>0. A tree-foliation {Σt}tT\{\Sigma_t\}_{t\in T} is a foliation of (S3,g)(S^3,g) by surfaces whose parameter space has the structure of a tree. For a leaf Σt\Sigma_t, let

diam(Σt)=supx,yΣt{distΣt(x,y)}\operatorname{diam}(\Sigma_t)=\sup_{x,y\in\Sigma_t}\{\operatorname{dist}_{\Sigma_t}(x,y)\}

denote its intrinsic diameter. Small tree-foliation conjecture. There exists a constant C>0C>0 such that (S3,g)(S^3,g) admits a tree-foliation {Σt}tT\{\Sigma_t\}_{t\in T} satisfying, for every tTt\in T,

diam(Σt)CΛ0,Area(Σt)CΛ0.\operatorname{diam}(\Sigma_t)\leq \frac{C}{\sqrt{\Lambda_0}},\qquad \operatorname{Area}(\Sigma_t)\leq \frac{C}{\Lambda_0}.

Such a foliation would provide the small-area and small-intrinsic-diameter sphere foliation needed to construct a continuously varying sweepout by short closed curves. The statement is presented as a conjectural ingredient in the paper; no resolution is supplied here.

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Sources & referencesView supporting material

Primary source

Yevgeny Liokumovich, Davi Maximo and Regina Rotman, “Length of a closed geodesic in 3-manifolds of positive scalar curvature”, arXiv:2504.05459 (2025).

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