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We generalize the definition of alpha invariant to arbitrary codimension. We also give a lower bound of these alpha invariants for K-semistable Q-Fano varieties and show that we can characterize projective spaces among all K-semistable Fano…

Algebraic Geometry · Mathematics 2020-01-28 Ziwen Zhu

For valuations on convex bodies in Euclidean spaces, there is by now a long series of characterization and classification theorems. The classical template is Hadwiger's theorem, saying that every rigid motion invariant, continuous,…

Metric Geometry · Mathematics 2016-09-02 Daniel Hug , Rolf Schneider

Given a germ of a smooth plane curve $(\{f(x,y)=0\},0)\subset (\mathbb K^2,0), \mathbb K=\mathbb R, \mathbb C$, with an isolated singularity, we define two invariants $I_f$ and $V_f\in \mathbb N\cup\{\infty\}$ which count the number of…

Differential Geometry · Mathematics 2024-05-30 J. W. Bruce , M. A. C. Fernandes , F. Tari

We study the c-affine surface area $\Omega^c$, recently introduced by Sch\"utt, Werner and Yalikun. We show that on the class of ball-bodies, $\Omega^c$ is maximized by a ball of radius $\frac{n}{n+1}$, and that a Santal\'o-type inequality…

Metric Geometry · Mathematics 2025-08-21 Shiri Artstein-Avidan , Arnon Chor

A nonlocal curvature flow is introduced to evolve locally convex curves in the plane. It is proved that this flow with any initial locally convex curve has a global solution, keeping the local convexity and the elastic energy of the…

Differential Geometry · Mathematics 2024-04-09 Laiyuan Gao , Horst Martini , Deyan Zhang

Over an algebraically closed base field $k$ of characteristic 2, the ring $R^G$ of invariants is studied, $G$ being the orthogonal group O(n) or the special orthogonal group SO(n) and acting naturally on the coordinate ring $R$ of the…

Rings and Algebras · Mathematics 2014-07-31 M. Domokos , P. E. Frenkel

It is proved that there exists an integer $L$ such that a framed manifold of dimension $2^l-2$, $l\le L$ has the trivial Kervaire Invariant.

Geometric Topology · Mathematics 2009-05-07 Peter M. Akhmet'ev

We prove that no smooth symmetric convex body $\Omega$ with at least one point of non-vanishing Gaussian curvature can admit an orthogonal basis of exponentials. (The non-symmetric case was proven by Kolountzakis). This is further evidence…

Classical Analysis and ODEs · Mathematics 2007-05-23 Alex Iosevich , Nets Hawk Katz , Terence Tao

Let $K$ be a convex body in $\mathbb{R}^n$ and $f : \partial K \rightarrow \mathbb{R}_+$ a continuous, strictly positive function with $\int\limits_{\partial K} f(x) d \mu_{\partial K}(x) = 1$. We give an upper bound for the approximation…

Metric Geometry · Mathematics 2017-07-07 Julian Grote , Elisabeth M. Werner

We extend the definition of the centroid body operator to an Orlicz--Lorentz centroid body operator on the star bodies in $\mathbb R^n$, and establish the sharp affine isoperimetric inequality that bounds (from below) the volume of the…

Functional Analysis · Mathematics 2017-07-11 Van Hoang Nguyen

For every smooth del Pezzo surface $S$, smooth curve $C\in|-K_{S}|$ and $\beta\in(0,1]$, we compute the $\alpha$-invariant of Tian $\alpha(S,(1-\beta)C)$ and prove the existence of K\"ahler--Einstein metrics on $S$ with edge singularities…

Algebraic Geometry · Mathematics 2016-07-12 Ivan Cheltsov , Jesus Martinez-Garcia

This paper is a continuation of [2], where we complete our partial proof of the Deser-Schwimmer conjecture on the structure of ``global conformal invariants''. Our theorem deals with such invariants P(g^n) that locally depend only on the…

Differential Geometry · Mathematics 2016-09-07 Spyros Alexakis

Let $V$ be a symmetric convex body in $\R^m$. We prove sharp Bernstein-type inequalities for entire functions of exponential type with the spectrum in $V$ and discuss certain properties of the extremal functions. Markov-type inequalities…

Classical Analysis and ODEs · Mathematics 2022-12-26 Michael I. Ganzburg

We generalise a theorem of Engman and Abreu--Freitas on the first invariant eigenvalue of non-negatively curved $S^{1}$-invariant metrics on $\mathbb{CP}^{1}$ to general toric K\"ahler metrics with non-negative scalar curvature. In…

Differential Geometry · Mathematics 2015-05-06 Stuart James Hall , Thomas Murphy

We prove a surface embedding theorem for 4-manifolds with good fundamental group in the presence of dual spheres, with no restriction on the normal bundles. The new obstruction is a Kervaire-Milnor invariant for surfaces and we give a…

Geometric Topology · Mathematics 2024-09-04 Daniel Kasprowski , Mark Powell , Arunima Ray , Peter Teichner

We study the asymptotic behavior of smooth, origin-symmetric, strictly convex bodies under the centro-affine normal flows. By means of a stability version of the Blaschke-Santal\'{o} inequality, we obtain regularity of the solutions…

Differential Geometry · Mathematics 2014-11-24 Mohammad N. Ivaki

We introduce extremal affine surface areas in a functional setting. We show their main properties. Among them are linear invariance, isoperimetric inequalities and monotonicity properties. We establish a new duality formula, which shows…

Metric Geometry · Mathematics 2024-02-27 Stephanie Egler , Elisabeth M. Werner

This result sharpens the bilinear to linear deduction of Lee and Vargas for extension estimates on the hyperbolic paraboloid in $\mathbb R^3$ to the sharp line, leading to the first scale-invariant restriction estimates, beyond the…

Classical Analysis and ODEs · Mathematics 2018-12-19 Betsy Stovall

Let $K\subset \mathbb{R}^n$, $n\geq 3$, be a convex body. A point $p$ the interior of $K$ is said to be a Larman point of $K$ if for every hyperplane $\Pi$ passing through $p$ the section $\Pi\cap K$ has a $(n-2)$-plane of symmetry. If $p$…

It is shown that every not-necessarily symmetric convex body $K$ in ${\mathbb R}^n$ has an affine image $\tilde{K}$ of $K$ such that the covering numbers of $\tilde{K}$ by growing dilates of the unit Euclidean ball, as well as those of the…

Metric Geometry · Mathematics 2023-04-04 Beatrice-Helen Vritsiou
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