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We introduce the vertical \(\widehat{A}\)-cowaist, a codimension-one invariant for partitioned manifolds. It extends the concept of infinite vertical \(\widehat{A}\)-cowaist for bands to arbitrary partitioned manifolds, which may be…

Differential Geometry · Mathematics 2026-05-19 Daoqiang Liu

We develop two connections between the quantitative framework of operator $K$-theory for geometric $C^*$-algebras and the problem of positive scalar curvature. First, we introduce a quantitative notion of higher index and use it to give a…

K-Theory and Homology · Mathematics 2024-09-02 Hao Guo , Zhizhang Xie , Guoliang Yu

We establish a sharp upper bound for the bottom spectrum of the Beltrami Laplacian on universal covers of closed Riemannian manifolds with scalar curvature lower bound. Moreover, we prove a scalar curvature rigidity theorem when this bound…

Differential Geometry · Mathematics 2025-09-01 Jinmin Wang , Bo Zhu

We use the Dirac operator technique to establish sharp distance estimates for compact spin manifolds under lower bounds on the scalar curvature in the interior and on the mean curvature of the boundary. In the situations we consider, we…

Differential Geometry · Mathematics 2024-05-22 Simone Cecchini , Rudolf Zeidler

We assign a measure to an upper semicontinuous function which is subharmonic with respect to the mean curvature operator, so that it agrees with the mean curvature of its graph when the function is smooth. We prove that the measure is…

Analysis of PDEs · Mathematics 2009-12-03 Qiuyi Dai , Neil Trudinger , Xujia Wang

Herein we present open problems and survey examples and theorems concerning sequences of Riemannian manifolds with uniform lower bounds on scalar curvature and their limit spaces. Examples of Gromov and of Ilmanen which naturally ought to…

Metric Geometry · Mathematics 2017-12-01 Christina Sormani

On complete non-compact manifolds with bounded sectional curvature, we consider a class of self-adjoint Dirac-type operators called Dirac-Schr\"odinger operators. Assuming two Dirac-Schr\"odinger operators coincide at infinity, by previous…

Differential Geometry · Mathematics 2026-04-14 Pengshuai Shi

In this paper, we focus on the distance estimate problem on complete manifolds with compact boundary and with lower scalar curvature bounds. On these manifolds, relative to a background manifold with nonnegative curvature operator, we…

Differential Geometry · Mathematics 2024-07-01 Daoqiang Liu

In this paper, we prove an extension of the noncompact version of Llarull's theorem due to Zhang and Li-Su-Wang-Zhang, giving an upper bound for the infimum of scalar curvature in terms of the bottom spectrum of the Laplacian. Moreover, we…

Differential Geometry · Mathematics 2026-01-22 Daoqiang Liu

In this note, we review some recent developments related to metric aspects of scalar curvature from the point of view of index theory for Dirac operators. In particular, we revisit index-theoretic approaches to a conjecture of Gromov on the…

Differential Geometry · Mathematics 2024-08-15 Rudolf Zeidler

In this paper we prove two sharp inequalities involving the normalized scalar curvature and the generalized normalized $\delta$-Casorati curvatures for slant submanifolds in quaternionic space forms. We also characterize those submanifolds…

Differential Geometry · Mathematics 2015-06-10 Jaewon Lee , Gabriel-Eduard Vîlcu

Let $M$ be a closed connected spin manifold such that its spinor Dirac operator has non-vanishing (Rosenberg) index. We prove that for any Riemannian metric on $V = M \times [-1,1]$ with scalar curvature bounded below by $\sigma > 0$, the…

Differential Geometry · Mathematics 2022-11-22 Rudolf Zeidler

In this paper, we establish new normal scalar curvature inequalities on a class of austere submanifolds by proving sharper DDVV-type inequalities on associated austere subspaces. We also provide some examples of austere submanifolds in this…

Differential Geometry · Mathematics 2026-01-06 Jianquan Ge , Ya Tao , Yi Zhou

Comparison theorems are foundational to our understanding of the geometric features implied by various curvature constraints. This paper considers manifolds with a positive lower bound on either scalar, 2-Ricci, or Ricci curvature, and…

Differential Geometry · Mathematics 2023-05-29 Sven Hirsch , Demetre Kazaras , Marcus Khuri , Yiyue Zhang

We study a pointwise inequality for submanifolds in real space forms involving the scalar curvature, the normal scalar curvature and the mean curvature. We translate it into an algebraic problem, allowing us to prove a slightly weaker…

Differential Geometry · Mathematics 2007-10-31 Franki Dillen , Johan Fastenakels , Joeri Van der Veken

We establish several inequalities for manifolds with positive scalar curvature and, more generally, for the scalar curvature bounded from below, in the spirit of the classical bound on the distances between conjugates points in surfaces…

Differential Geometry · Mathematics 2018-10-30 Misha Gromov

The $\mathrm{K}$-cowaist $\text{K-cw}_2 (M)$ and the $\hat{\mathsf{A}}$-cowaist $\hat{\mathrm{A}}$-$\mathrm{cw}_2 (M)$ are two interesting invariants on a manifold $M$, which are closely related to the existence of the positive scalar…

Differential Geometry · Mathematics 2023-09-04 Xiangsheng Wang

Using Weitzenb\"ock techniques on any compact Riemannian spin manifold we derive a general inequality depending on a real parameter and joining the spectrum of the Dirac operator with terms depending on the Ricci tensor and its first…

Differential Geometry · Mathematics 2007-05-23 Klaus-Dieter Kirchberg

In this article, we study the topological complexity of manifolds with a lower scalar curvature bound. We introduce a small scale index theorem to establish an upper bound for Gromov's simplicial norm of the Poincar\'e dual of the A-hat…

Differential Geometry · Mathematics 2025-11-05 Qiaochu Ma , Guoliang Yu

We develop a general deformation principle for families of Riemannian metrics on smooth manifolds with possibly non-compact boundary, preserving lower scalar curvature bounds. The principle is used in order to strengthen boundary…

Differential Geometry · Mathematics 2025-03-06 Helge Frerichs
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