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We observe that the maximal open set of constant curvature k in a Riemannian manifold with curvature bounded below or above by k has a convexity type property, which we call "two-convexity". This statement is used to prove a number of…

Differential Geometry · Mathematics 2020-10-20 D. Panov , A. Petrunin

Given a locally compact quantum group $\mathbb{G}$ and a closed quantum subgroup $\mathbb{H}$, we show that $\mathbb{G}$ is amenable if and only if $\mathbb{H}$ is amenable and $\mathbb{G}$ acts amenably on the quantum homogenous space…

Operator Algebras · Mathematics 2018-05-24 Jason Crann

In this paper, we deal with cohomological properties of weak amenability, cyclic amenability, cyclic weak amenability and point amenability of Banach algebras. We look at some hereditary properties of them and show that continuous…

Functional Analysis · Mathematics 2022-10-10 M. J. Mehdipour , A. Rejali

We consider a smooth Euclidean solid cone endowed with a smooth homogeneous density function used to weight Euclidean volume and hypersurface area. By assuming convexity of the cone and a curvature-dimension condition we prove that the…

Differential Geometry · Mathematics 2013-04-17 Antonio Cañete , César Rosales

We shall develop two notions of pointwise amenability, namely pointwise Connes amenability and pointwise $w^*$-approximate Connes amenability, for dual Banach algebras which take the $w^*$-topology into account. We shall study these…

Functional Analysis · Mathematics 2017-06-23 Mannane Shakeri , Amin Mahmoodi

We introduce holed cone structures on 3-manifolds to generalize cone structures. In the same way as a cone structure, a holed cone structure induces the holonomy representation. We consider the deformation space consisting of the holed cone…

Geometric Topology · Mathematics 2025-06-04 Ken'ichi Yoshida

A polymer repelled by unfavorable interactions with a uniform flat surface may still be pinned to attractive edges and corners. This is demonstrated by considering adsorption of a two-dimensional ideal polymer to an attractive corner of a…

Statistical Mechanics · Physics 2017-12-27 Raz Halifa Levi , Yacov Kantor , Mehran Kardar

This article investigates the numerical approximation of shape optimization problems with PDE constraint on classes of convex domains. The convexity constraint provides a compactness property which implies well posedness of the problem.…

Optimization and Control · Mathematics 2018-10-26 Sören Bartels , Gerd Wachsmuth

Problems related to projections on closed convex cones are frequently encountered in optimization theory and related fields. To study these problems, various unifying ideas have been introduced, including asymmetric vector-valued norms and…

Optimization and Control · Mathematics 2022-04-11 Jani Jokela

We consider the classical minimum and maximum cut problems: find a partition of vertices of a graph into two disjoint subsets that minimize or maximize the sum of the weights of edges with endpoints in different subsets. It is known that if…

Combinatorics · Mathematics 2024-02-20 Andrei V. Nikolaev , Alexander V. Korostil

Let $T$ be a Banach algebra homomorphism from a Banach algebra $\mathcal B$ to a Banach algebra $\mathcal A$ with $\|T\|\leq 1$. Recently it has been obtained some results about Arens regularity and also various notions of amenability of…

Functional Analysis · Mathematics 2015-02-19 F. Abtahi , A. Ghafarpanah , A. Rejali

In this paper we find some necessary and sufficient conditions for a Banach algebra to be amenable or weakly amenable, by applying the homomorphisms on Banach algebras.

Functional Analysis · Mathematics 2007-05-23 M. Eshaghi Gordji

In this article we address a number of features of the moduli space of spherical metrics on connected, compact, orientable surfaces with conical singularities of assigned angles, such as its non-emptiness and connectedness. We also consider…

Differential Geometry · Mathematics 2019-07-26 Gabriele Mondello , Dmitri Panov

In this study, the properties of convex hexagons that can form rotationally symmetric edge-to-edge tilings are discussed. Because the convex hexagons are equilateral convex parallelohexagons, convex pentagons generated by bisecting the…

Metric Geometry · Mathematics 2022-05-05 Teruhisa Sugimoto

Motivated by applications in CNC machining, we provide a characterization of surfaces which are enveloped by a one-parametric family of congruent rotational cones. As limit cases, we also address developable surfaces and ruled surfaces. The…

Differential Geometry · Mathematics 2023-09-14 Mikhail Skopenkov , Pengbo Bo , Michael Bartoň , Helmut Pottmann

We address the following question: Determine the affine cones over smooth projective varieties which admit an action of a connected algebraic group different from the standard C*-action by scalar matrices and its inverse action. We show in…

Algebraic Geometry · Mathematics 2010-01-30 Takashi Kishimoto , Yuri Prokhorov , Mikhail Zaidenberg

Convex geometry is a closure space $(G,\phi)$ with the anti-exchange property. A classical result of Edelman and Jamison (1985) claims that every finite convex geometry is a join of several linear sub-geometries, and the smallest number of…

Combinatorics · Mathematics 2018-08-09 Kira Adaricheva , Gent Gjonbalaj

We characterise which simplicial surfaces can be folded onto a triangle. We define a notion of folding that incorporates the non-intersection-properties of real materials. All of the surfaces foldable onto a triangle admit a…

Combinatorics · Mathematics 2019-04-30 Markus Baumeister

A real projective orbifold is an $n$-dimensional orbifold modeled on $\mathbb{RP}^n$ with the group $PGL(n+1, \mathbb{R})$. We concentrate on an orbifold that contains a compact codimension $0$ submanifold whose complement is a union of…

Geometric Topology · Mathematics 2014-05-29 Suhyoung Choi

We answer an open question of Grigorchuk and Zuk about amenability using random walks. Our results separate the class of amenable groups from the closure of subexponentially growing groups under the operations of group extension and direct…

Group Theory · Mathematics 2011-11-10 Laurent Bartholdi , Balint Virag