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Analogously to the concept of a curvature of curve and surface, in the differential geometry, in the main part of this paper the concept of the curvature of the hyper-dimensional vector spaces of Riemannian metric is generally defined. The…

Differential Geometry · Mathematics 2007-05-23 Branko Saric

We develop two types of integral formulas for the perimeter of a convex body K in planar geometries. We derive Cauchy-type formulas for perimeter in planar Hilbert geometries. Specializing to H^2 we get a formula that appears to be new. We…

Differential Geometry · Mathematics 2007-05-23 Ralph Alexander , I. D. Berg , Robert L. Foote

A generalization of the cosine of the Friedrichs angle between two subspaces to a parameter associated to several closed subspaces of a Hilbert space is given. This parameter is used to analyze the rate of convergence in the von…

Functional Analysis · Mathematics 2012-09-06 Catalin Badea , Sophie Grivaux , Vladimir Muller

Convex algebraic geometry concerns the interplay between optimization theory and real algebraic geometry. Its objects of study include convex semialgebraic sets that arise in semidefinite programming and from sums of squares. This article…

Optimization and Control · Mathematics 2010-06-28 Philipp Rostalski , Bernd Sturmfels

We survey elementary results in Minkowski spaces (i.e. finite dimensional Banach spaces) that deserve to be collected together, and give simple proofs for some of them. We place special emphasis on planar results. Many of these results have…

Metric Geometry · Mathematics 2007-08-22 Horst Martini , Konrad J Swanepoel , Gunter Weiss

In \cite{CC1}, Cheeger-Colding considered manifolds with lower Ricci curvature bound and gave some almost rigidity results about warped products including almost metric cone rigidity and quantitative splitting theorem. As a generalization…

Differential Geometry · Mathematics 2022-01-21 Lina Chen

This paper is concerned with restricted families of projections in $\mathbb{R}^{3}$. Let $K \subset \mathbb{R}^{3}$ be a Borel set with Hausdorff dimension $\dim K = s > 1$. If $\mathcal{G}$ is a smooth and sufficiently well-curved…

Classical Analysis and ODEs · Mathematics 2016-02-03 Tuomas Orponen

We revisit an ingenious argument of K. Ball to provide sharp estimates for the volume of sections of a convex body in John's position. Our technique combines the geometric Brascamp-Lieb inequality with a generalised Parseval-type identity.…

Metric Geometry · Mathematics 2026-03-31 David Alonso-Gutiérrez , Silouanos Brazitikos , Giorgos Chasapis

We consider a 3-dimensional Riemannian manifold V with a metric g and an affinor structure q. The local coordinates of these tensors are circulant matrices. In V we define an almost conformal transformation. Using that definition we…

Differential Geometry · Mathematics 2011-06-15 Georgi Dzhelepov , Dimitar Razpopov , Iva Dokuzova

We study the arithmetic properties of projective varieties of almost minimal degree, that is of non-degenerate irreducible projective varieties whose degree exceeds the codimension by precisely 2. We notably show, that such a variety $X…

Commutative Algebra · Mathematics 2007-05-23 Markus Brodmann , Peter Schenzel

We give upper and lower bounds for the ratio of the volume of metric ball to the area of the metric sphere in Finsler-Hadamard manifolds with pinched S-curvature. We apply these estimates to find the limit at the infinity for this ratio.…

Differential Geometry · Mathematics 2011-10-11 Alexandr A. Borisenko , Eugeny A. Olin

We give a local characterization of the existence of Kazhdan projections for arbitary families of Banach space representations of a compactly generated locally compact group $G$. We also define and study a natural generalization of the Fell…

Functional Analysis · Mathematics 2021-03-25 Mikael de la Salle

We prove that a compact stratied space satises the Riemannian curvature-dimension condition RCD(K, N) if and only if its Ricci tensor is bounded below by K $\in$ R on the regular set, the cone angle along the stratum of codimension two is…

Differential Geometry · Mathematics 2018-06-11 J. Bertrand , C Ketterer , Ilaria Mondello , T. Richard

Understanding the stochastic behavior of random projections of geometric sets constitutes a fundamental problem in high dimension probability that finds wide applications in diverse fields. This paper provides a kinematic description for…

Probability · Mathematics 2026-03-17 Qiyang Han , Huachen Ren

In this paper we investigate real convex-transitive Banach spaces X, which admit a 1-dimensional bicontractive projection P on X. Various mild conditions regarding the weak topology and the geometry of the norm are provided, which guarantee…

Functional Analysis · Mathematics 2007-05-23 Jarno Talponen

We prove several estimates for the moments of arbitrary measures on convex bodies. We apply these estimates to show a new slicing inequality for measures on convex bodies. We also deduce estimates for the outer volume ratio distance from an…

Metric Geometry · Mathematics 2017-12-19 Sergey Bobkov , Bo'az Klartag , Alexander Koldobsky

Motivated by the questions in the theory of Fredholm stability in Banach space and Kato's strictly singular operators we answer several natural questions concerning ``orthogonality'' in normed spaces and the properties of metric…

Functional Analysis · Mathematics 2021-07-07 Boris Burshteyn , Alexander Volberg

We consider polyhedral approximations of strictly convex compacta in finite dimensional Euclidean spaces (such compacta are also uniformly convex). We obtain the best possible estimates for errors of considered approximations in the…

Functional Analysis · Mathematics 2010-10-13 Maxim V. Balashov , Dušan Repovš

We generalize the notions of the Futaki invariant and extremal vector field of a compact K\"ahler manifold to the general almost-Kahler case and show the periodicity of the extremal vector field when the symplectic form represents an…

Differential Geometry · Mathematics 2010-04-22 Mehdi Lejmi

We introduce a notion of $k$-convexity and explore polygons in the plane that have this property. Polygons which are \mbox{$k$-convex} can be triangulated with fast yet simple algorithms. However, recognizing them in general is a 3SUM-hard…

Computational Geometry · Computer Science 2010-07-22 Oswin Aichholzer , Franz Aurenhammer , Erik D. Demaine , Ferran Hurtado , Pedro Ramos , Jorge Urrutia