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We study geometric structures of $\mathcal{W}_4$-type in the sense of A. Gray on a Riemannian manifold. If the structure group $\mathrm{G} \subset \SO(n)$ preserves a spinor or a non-degenerate differential form, its intrinsic torsion…

Differential Geometry · Mathematics 2013-11-06 Ilka Agricola , Thomas Friedrich

We establish mean curvature estimate for immersed hypersurface with nonnegative extrinsic scalar curvature in Riemannian manifold $(N^{n+1}, \bar g)$ through regularity study of a degenerate fully nonlinear curvature equation in general…

Differential Geometry · Mathematics 2017-04-05 Pengfei Guan , Siyuan Lu

We discuss the integrability of orthogonal almost complex structures on Riemannian products of even-dimensional round spheres and give a partial answer to the question raised by E. Calabi concerning the existence of complex structures on a…

Differential Geometry · Mathematics 2013-01-31 Yunhee Euh , Kouei Sekigawa

We prove the existence and uniqueness up to translations of the solution to a Minkowski type problem for the torsional rigidity in the class of open bounded convex subsets of the $n$-dimensional Euclidean space. For the existence part we…

Analysis of PDEs · Mathematics 2008-09-29 A. Colesanti , M. Fimiani

Motivated by analogous results in locally conformal symplectic geometry, we study different classes of G$_2$-structures defined by a locally conformal closed 3-form. In particular, we give a complete characterization of invariant exact…

Differential Geometry · Mathematics 2019-02-12 Giovanni Bazzoni , Alberto Raffero

We study the classification of special almost hermitian manifolds in Gray and Hervella's type classes. We prove that the exterior derivatives of the symplectic form and the complex volume form contain all the information about the intrinsic…

Differential Geometry · Mathematics 2009-11-10 Francisco Martin Cabrera

When two smooth manifold bundles over the same base are fiberwise tangentially homeomorphic, the difference is measured by a homology class in the total space of the bundle. We call this the relative smooth structure class. Rationally and…

K-Theory and Homology · Mathematics 2012-04-10 Sebastian Goette , Kiyoshi Igusa , Bruce Williams

We consider surfaces embedded in a Riemannian manifold of arbitrary dimension and prove that many aspects of their differential geometry can be expressed in terms of a Poisson algebraic structure on the space of smooth functions of the…

Differential Geometry · Mathematics 2010-01-13 Joakim Arnlind , Jens Hoppe , Gerhard Huisken

As a generalization of anti-invariant Riemannian submersions and Lagrangian Riemannian submersions, we introduce the notions of h-anti-invariant submersions and h-Lagrangian submersions from almost quaternionic Hermitian manifolds onto…

Differential Geometry · Mathematics 2015-07-17 Kwang-Soon Park

An isometric immersion $f: M^{n} \rightarrow \tilde M^{m}$ from an $n$-dimensional Riemannian manifold $M^{n}$ into an almost Hermitian manifold $\tilde M^{m}$ of complex dimension $m$ is called pointwise slant if its Wirtinger angles…

Differential Geometry · Mathematics 2020-03-16 Azeb Alghanemi , Noura M. Al-houiti , Bang-Yen Chen , Siraj Uddin

In this paper we introduce the concept of pointwise bi-slant submanifolds of locally product Riemannian manifolds and studied warped product pointwise bi-slant submanifolds of locally product Riemannian manifolds. We obtain some…

Differential Geometry · Mathematics 2023-09-18 Prince Majeed , Mehraj Ahmad Lone

The paper is devoted to Hardy type inequalities on closed manifolds. By means of various weighted Ricci curvatures, we establish several sharp Hardy type inequalities on closed weighted Riemannian manifolds. Our results complement in…

Differential Geometry · Mathematics 2021-07-01 Canjun Meng , Han Wang , Wei Zhao

This is the first part of a series of papers. The whole series aims to develop the tools for the study of all almost Hermitian symmetric structures in a unified way. In particular, methods for the construction of invariant operators, their…

dg-ga · Mathematics 2008-02-03 Andreas Cap , Jan Slovak , Vladimir Soucek

We construct new compact manifolds endowed with closed $\mathrm{G}_2$ structures that satisfy the topological properties found by Joyce and Baraglia for the existence of a torsion-free $\mathrm{G}_2$ structure in the same cohomology class.…

Differential Geometry · Mathematics 2025-08-19 Lucía Martín-Merchán

There is a well developed theory of weakly symmetric Riemannian manifolds. Here it is shown that several results in the Riemannian case are also valid for weakly symmetric pseudo-Riemannian manifolds, but some require additional hypotheses.…

Differential Geometry · Mathematics 2011-07-26 Zhiqi Chen , Joseph A. Wolf

We describe how to approximate the Riemann curvature tensor as well as sectional curvatures on possibly infinite-dimensional shape spaces that can be thought of as Riemannian manifolds. To this end, we extend the variational time…

Numerical Analysis · Mathematics 2019-12-17 Alexander Effland , Behrend Heeren , Martin Rumpf , Benedikt Wirth

We review the notion of shape tensor of an embedded manifold, which efficiently combines intrinsic and extrinsic geometry, and allows for intuitive understanding of some basic concepts of classical differential geometry, such as parallel…

Mathematical Physics · Physics 2018-08-10 Vaclav Zatloukal

We discuss some specializations of the frames of flat orthonormal frame bundles over geometries of indefinite signature, and the resulting symmetries of families of embedded Riemannian or pseudo-Riemannian geometries. The specializations…

General Relativity and Quantum Cosmology · Physics 2013-02-18 Frank B. Estabrook

This paper provides an introduction to exploded manifolds. The category of exploded manifolds is an extension of the category of smooth manifolds with an excellent holomorphic curve theory. Each exploded manifold has a tropical part which…

Symplectic Geometry · Mathematics 2017-09-14 Brett Parker

In this paper we study critial isometric and minimal isometric embeddings of classes of Riemannian metrics which we call {\it quasi-$k$-curved metrics}. Quasi-$k$-curved metrics generalize the metrics of space forms. We construct explicit…

dg-ga · Mathematics 2008-02-03 Thomas Ivey , J. M. Landsberg