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A classic theorem of Kazhdan and Margulis states that for any semisimple Lie group without compact factors, there is a positive lower bound on the covolume of lattices. H. C. Wang's subsequent quantitative analysis showed that the…

Geometric Topology · Mathematics 2018-09-25 Ilesanmi Adeboye , McKenzie Wang , Guofang Wei

Let $(X,\Delta)$ be an $n$-dimensional $\epsilon$-klt log $\QQ$-Fano pair. We give an upper bound for the volume ${\rm Vol}(-(K_X+\Delta))=(-(K_X+\Delta))^n$ when $n=2$ or $n=3$ and $X$ is {$\QQ$-factorial} of $\rho(X)=1$. This bound is…

Algebraic Geometry · Mathematics 2012-04-13 Ching-Jui Lai

We give estimates on the number $AL_H(x)$ of arithmetic lattices $\Gamma$ of covolume at most $x$ in a simple Lie group $H$. In particular, we obtain a first concrete estimate on the number of arithmetic 3-manifolds of volume at most $x$.…

Group Theory · Mathematics 2010-04-23 Mikhail Belolipetsky , Tsachik Gelander , Alex Lubotzky , Aner Shalev

Let $X$ be a Gorenstein minimal projective $n$-fold with at worst locally factorial terminal singularities, and suppose that the canonical map of $X$ is generically finite onto its image. When $n<4$, the canonical degree is universally…

Algebraic Geometry · Mathematics 2016-12-19 Rong Du , Yun Gao

In this paper we obtain an analogue of Toponogov theorem in dimension 3 for compact manifolds $M^3$ with nonnegative Ricci curvature and strictly convex boundary $\partial M$. Here we obtain a sharp upper bound for the length…

Differential Geometry · Mathematics 2019-10-09 Abraão Mendes

We prove lower bounds for the minimum distance of algebraic geometry codes over surfaces whose canonical divisor is either nef or anti-strictly nef and over surfaces without irreducible curves of small genus. We sharpen these lower bounds…

Algebraic Geometry · Mathematics 2020-03-04 Yves Aubry , Elena Berardini , Fabien Herbaut , Marc Perret

We obtain sharp volume bounds on the boundaries of Alexandrov spaces with given lower curvature bound, dimension, and radius. We also completely classify the rigidity case and analyze almost rigidity. Our results are new even for smooth…

Differential Geometry · Mathematics 2023-08-29 Qin Deng , Vitali Kapovitch

We prove that the $5$-canonical map of every minimal projective $3$-fold $X$ with $K_X^3\geq 86$ is stably birational onto its image, which loosens previous requirements $K_X^3>4355^3$ and $K_X^3>12^3$ respectively given by Todorov and…

Algebraic Geometry · Mathematics 2025-10-07 Meng Chen , Sicheng Ding

We give an upper bound on the volume vol(P*) of a polytope P* dual to a d-dimensional lattice polytope P with exactly one interior lattice point, in each dimension d. This bound, expressed in terms of the Sylvester sequence, is sharp, and…

Combinatorics · Mathematics 2016-11-09 Gabriele Balletti , Alexander M. Kasprzyk , Benjamin Nill

For smooth projective 3-folds of general type, we prove that the relative canonical stability $\mu_s(3)\leq 8$. This is induced from our improved result of Koll\'ar: the m-canonical map of a smooth projective 3-fold of general type is…

Algebraic Geometry · Mathematics 2007-05-23 Meng Chen

Given a sequence of properly embedded minimal surfaces in a $3$-manifold with local bounds on area and genus, we prove subsequential convergence, smooth away from a discrete set, to a smooth embedded limit surface, possibly with…

Differential Geometry · Mathematics 2024-01-26 Brian White

We study the canonical stability index of nonsingular projective varieties of general type with either large canonical volume or large geometric genus. As applications of a general extension theorem established in the first part, we prove…

Algebraic Geometry · Mathematics 2017-01-26 Meng Chen , Zhi Jiang

Given $\epsilon>0$, we show that over an algebraically closed field of characteristic $p>5$, the anticanonical volume of a Fano threefold $X$ (with arbitrary singularities) whose anticanonical divisor has Seshadri constant…

Algebraic Geometry · Mathematics 2020-08-05 Ziquan Zhuang

In this paper, we give a partial affirmative answer to the BAB conjecture for $3$-folds in characteristic $p>5$. Specifically, we prove that a set $\mathcal{D}$ of weak Fano $3$-folds over an uncountable algebraically closed field is…

Algebraic Geometry · Mathematics 2024-03-06 Kenta Sato

Let $N$ be a compact, orientable hyperbolic 3-manifold whose boundary is a connected totally geodesic surface of genus $2$. If $N$ has Heegaard genus at least $5$, then its volume is greater than $2V_{\rm oct}$, where $V_{\rm…

Geometric Topology · Mathematics 2025-12-19 Jason DeBlois , Peter B. Shalen

We give the sharp lower bound of the volume product of $n$-dimensional convex bodies which are invariant under a discrete subgroup $SO(K)=\{ g \in SO(n); g(K)=K \}$, where $K$ is an $n$-cube or $n$-simplex. This provides new partial results…

Metric Geometry · Mathematics 2022-03-29 Hiroshi Iriyeh , Masataka Shibata

The results of Culler and Shalen for 2,3 or 4-free hyperbolic 3-manifolds are contingent on properties specific to and special about rank two subgroups of a free group. Here we determine what construction and algebraic information is…

Geometric Topology · Mathematics 2012-05-03 Rosemary K. Guzman

Consider a component of the Hilbert scheme whose general point corresponds to a degree d genus g smooth irreducible and nondegenerate curve in a projective variety X. We give lower bounds for the dimension of such a component when X is P^3,…

Algebraic Geometry · Mathematics 2008-08-28 Dawei Chen

A classification theorem is given of smooth threefolds of $\Bbb P^5$ covered by a family of dimension at least three of plane integral curves of degree $d\geq 2.$ It is shown that for such a threefold $X$ there are two possibilities:…

alg-geom · Mathematics 2008-02-03 Emilia Mezzetti , Dario Portelli

This paper presents some finiteness results for the number of boundary slopes of immersed essential surfaces of given genus g in a compact 3-manifold with torus boundary. In the case of hyperbolic 3-manifolds we obtain uniform quadratic…

Geometric Topology · Mathematics 2007-05-23 Joel Hass , J. Hyam Rubinstein , Shicheng Wang