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In this article we give a classification of three dimensional m-quasi Einstein manifolds with two distinct Ricci-eigen values. Our study provides explicit description of local and complete metrics and potential functions. We also describe…

Differential Geometry · Mathematics 2017-12-12 Jongsu Kim , Jinwoo Shin

To a continuous action of a vector group on a $C^*$-algebra, twisted by the imaginary exponential of a symplectic form, one associates a Rieffel deformed algebra as well as a twisted crossed product. We show that the second one is…

Operator Algebras · Mathematics 2014-06-30 I. Beltita , M. Mantoiu

The goal of this article is to study the geometry of Bach-flat noncompact steady quasi-Einstein manifolds. We show that a Bach-flat noncompact steady quasi-Einstein manifold $(M^{n},\,g)$ with positive Ricci curvature such that its…

Differential Geometry · Mathematics 2016-12-15 M. Ranieri , E. Ribeiro

In this paper, we investigate the null (light-like) sectional curvatures of Lorentzian warped product manifolds. We derive the formulas for the null sectional curvature of many well-known warped product space-time models such as multiply…

Differential Geometry · Mathematics 2016-08-16 Bengi R. Yavuz , Bülent ünal , Fernando Dobarro

In this paper we define an associative stringy product for the twisted orbifold K-theory of a compact, almost complex orbifold X. This product is defined on the twisted K-theory of the inertia orbifold of X, where the twisting gerbe is…

Algebraic Topology · Mathematics 2008-11-21 Alejandro Adem , Yongbin Ruan , Bin Zhang

We investigate cases where the finite dual coalgebra of a twisted tensor product of two algebras is a cotwisted tensor product of their respective finite dual coalgebras. This is achieved by interpreting the finite dual as a topological…

Rings and Algebras · Mathematics 2025-01-20 Manuel L. Reyes

In this paper we study fundamental geometric properties of doubly warped product immersion which is an extension of warped product immersion. Moreover, we study geometric inequality for doubly warped products isometrically immersed in…

Differential Geometry · Mathematics 2014-10-09 Morteza Faghfouri , Ayyoub Majidi

In this paper, we introduce a class of twisted multiparameter singular integrals on $\mathbb{R}^{2m}$, motivated by the Cauchy--Szeg\H{o} projections and the solving operators for $\bar{\partial}_b$ on a broad family of quadratic surfaces…

Classical Analysis and ODEs · Mathematics 2026-03-30 Zunwei Fu , Ji Li , Chong-Wei Liang , Wei Wang , Qingyan Wu

We give estimates on the intrinsic and the extrinsic curvature of manifolds that are isometrically immersed as cylindrically bounded submanifolds of warped products. We also address extensions of the results in the case of submanifolds of…

Differential Geometry · Mathematics 2010-09-20 L. J. Alias , G. P. Bessa , J. F. Montenegro , P. Piccione

We define the twisted tensor product of two enriched categories, which generalizes various sorts of `products' of algebraic structures, including the bicrossed product of groups, the twisted tensor product of (co)algebras and the double…

Category Theory · Mathematics 2011-12-06 Aura Bârdeş , Dragoş Ştefan

Topological invariants such as winding numbers and linking numbers appear as charges of topological solitons in diverse nonlinear physical systems described by a unit vector field defined on two and three dimensional manifolds. While the…

Pattern Formation and Solitons · Physics 2024-01-23 Radha Balakrishnan , Rossen Dandoloff , Avadh Saxena

We prove an existence result for the prescribed Ricci curvature equation for certain doubly warped product metrics on $\mathbb{S}^{d_1+1}\times \mathbb{S}^{d_2}$, where $d_i \geq 2$. If $T$ is a metric satisfying certain curvature…

Differential Geometry · Mathematics 2020-10-13 Timothy Buttsworth , Anusha M. Krishnan

We introduce a definition of braided tensor product $\operatorname{M}\overline{\boxtimes}\operatorname{N}$ of von Neumann algebras equipped with an action of a quasi-triangular quantum group $\mathbb{G}$ (this includes the case when…

Operator Algebras · Mathematics 2024-12-24 Kenny De Commer , Jacek Krajczok

This paper considers the relationship between geometry, symmetry and fundamental interactions -- gravity and those mediated by gauge fields. We explore product spacetimes which a) have the necessary symmetries for gauge interactions and…

General Relativity and Quantum Cosmology · Physics 2022-05-17 Tom Lawrence

We consider noncommutative geometries obtained from a triangular Drinfeld twist. This allows to construct and study a wide class of noncommutative manifolds and their deformed Lie algebras of infinitesimal diffeomorphisms. This way symmetry…

Quantum Algebra · Mathematics 2010-05-13 Paolo Aschieri

We study conformal product structures on compact reducible Riemannian manifolds, and show that under a suitable technical assumption, the underlying Riemannian mani\-folds are either conformally flat, or triple products, \emph{i.e.} locally…

Differential Geometry · Mathematics 2026-01-14 Andrei Moroianu , Mihaela Pilca

Firstly we provide new characterizations for doubly warped product manifolds. Then we consider several types of gradient solitons on them such as Riemann, Ricci, Yamabe and conformal and examine the effect of a gradient soliton on a doubly…

Differential Geometry · Mathematics 2025-08-04 Adara M. Blaga , Hakan M. Taştan

We study the notion of $1$-twisted semi-homogeneous vector bundles on $\mathbb{G}_m$-gerbes over abelian varieties, and classify point objects in the twisted derived categories of abelian varieties. As an application, we classify the…

Algebraic Geometry · Mathematics 2026-03-25 Ruoxi Li

Information geometry is an important tool to study statistical models. There are some important examples in statistical models which are regarded as warped products. In this paper, we study information geometry of warped products. We…

Differential Geometry · Mathematics 2022-07-26 Yasuaki Fujitani

Let M be a complete n-dimensional Riemannian spin manifold, partitioned by q two-sided hypersurfaces which have a compact transverse intersection N and which in addition satisfy a certain coarse transversality condition. Let E be a…

K-Theory and Homology · Mathematics 2018-09-25 Thomas Schick , Mostafa Esfahani Zadeh