The injectivity radius--spherical radius comparison conjecture

Let (Mn,g)(M^n,g) be a complete Riemannian manifold. Write Inj(M)\operatorname{Inj}(M) for its injectivity radius and RadSn(M)\operatorname{Rad}_{\mathbb S^n}(M) for its spherical radius. The injectivity radius--spherical radius comparison conjecture. There exists a universal constant cnc_n such that

Inj(M)cnRadSn(M).\operatorname{Inj}(M)\leq c_n\operatorname{Rad}_{\mathbb S^n}(M).

The conjecture is motivated by the inequalities relating injectivity radius, filling radius, Uryson width, and spherical radius. The source gives no resolution; it would turn bounds on spherical radius from positive scalar curvature into bounds on injectivity radius.

Sources & referencesView supporting material

Primary source

Jinmin Wang, Zhizhang Xie, Guoliang Yu and Bo Zhu, “Filling Radius, Quantitative K-theory and Positive Scalar Curvature”, arXiv:2311.15347 (2024).

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