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Let $(M,g)$ be a smooth compact Riemannian manifold of dimension $n$ with smooth boundary $\partial M$, admitting a scalar-flat conformal metric. We prove that the supremum of the isoperimetric ratio over the scalar-flat conformal class is…

Differential Geometry · Mathematics 2019-10-04 Xuezhang Chen , Tianling Jin , Yuping Ruan

We present a method for proving the existence of solutions to a class of one dimensional variational problems. The method is demonstrated by two examples of optimal interpolation problems which are motivated by engineering applications. In…

Differential Geometry · Mathematics 2014-02-25 Philip Schrader

We present a simple proof of the surface classification theorem using normal curves. This proof is analogous to Kneser's and Milnor's proof of the existence and uniqueness of the prime decomposition of 3-manifolds. In particular, we do not…

Geometric Topology · Mathematics 2026-02-10 Fethi Ayaz , Marc Kegel , Klaus Mohnke

We use Menger's Theorem and K\"onig's Line Colouring Theorem to show that in any tripartite graph with two complete (bipartite) sides the maximum number of pairwise edge-disjoint triangles equals the minimum number of edges that meet all…

Combinatorics · Mathematics 2023-07-19 Naivedya Amarnani , Amaury De Burgos , Wayne Broughton

We investigate the combinatorial analogues, in the context of normal surfaces, of taut and transversely measured (codimension 1) foliations of 3-manifolds. We establish that the existence of certain combinatorial structures, a priori weaker…

Geometric Topology · Mathematics 2007-05-23 Danny Calegari

Mantel's theorem states that every $n$-vertex graph with $\lfloor \frac{n^2}{4} \rfloor +t$ edges, where $t>0$, contains a triangle. The problem of determining the minimum number of triangles in such a graph is usually referred to as the…

Combinatorics · Mathematics 2021-06-14 József Balogh , Felix Christian Clemen

The main goal of the paper is to prove the sandwich theorem for geodesic convex functions in a complete Riemannian manifold. Then by using this theorem we have proved an inequality in a manifold with bounded sectional curvature. Finally, we…

Differential Geometry · Mathematics 2018-06-25 Absos Ali Shaikh , Ravi P. Agarwal , Chandan Kumar Mondal

The persistence of excitation (PE) condition is sufficient to ensure parameter convergence in adaptive estimation problems. Recent results on adaptive estimation in reproducing kernel Hilbert spaces (RKHS) introduce PE conditions for RKHS.…

Systems and Control · Electrical Eng. & Systems 2020-09-08 Sai Tej Paruchuri , Jia Guo , Andrew Kurdila

In this paper, we study the space of translational limits T(M) of a surface M properly embedded in R^3 with nonzero constant mean curvature and bounded second fundamental form. There is a natural map T which assigns to any surface M' in…

Differential Geometry · Mathematics 2008-05-13 William H. Meeks , Giuseppe Tinaglia

The goal of this paper is to prove the full geometric Bogomolov conjecture. We first reduce it to the case that the extension of the base fields has transcendence degree 1, and then we prove the later case by intersection theory in…

Algebraic Geometry · Mathematics 2022-07-20 Junyi Xie , Xinyi Yuan

In this paper we study surfaces in Euclidean 3-space that satisfy a Weingarten condition of linear type as $\kappa_1=m \kappa_2 +n$, where $m$ and $n$ are real numbers and $\kappa_1$ and $\kappa_2$ denote the principal curvatures at each…

Differential Geometry · Mathematics 2007-06-13 Rafael López

Tollefson described a variant of normal surface theory for 3-manifolds, called Q-theory, where only the quadrilateral coordinates are used. Suppose $M$ is a triangulated, compact, irreducible, boundary-irreducible 3-manifold. In Q-theory,…

Geometric Topology · Mathematics 2010-09-09 Chan-Ho Suh

We strengthen a conjecture by the author. This conjecture is a Bogomolov-Gieseker type inequality involving the third Chern character of mixed tilt-stable complexes on fibred threefolds. We extend it from complexes of mixed tilt-slope zero…

Algebraic Geometry · Mathematics 2022-06-22 Hao Max Sun

We give a conjectural construction of Bridgeland stability conditions on the derived category of fibred threefolds. The construction depends on a conjectural Bogomolov-Gieseker type inequality for certain stable complexes. It can be…

Algebraic Geometry · Mathematics 2022-06-22 Hao Max Sun

We prove a version of the Khinchine--Groshev theorem for Diophantine approximation of matrices subject to a congruence condition. The proof relies on an extension of the Dani correspondence to the quotient by a congruence subgroup. This…

Number Theory · Mathematics 2019-02-06 Erez Nesharim , Rene Rühr , Ronggang Shi

We give a sufficient condition for the existence of a holomorphic tubular neighborhood of a compact Riemann surface holomorphically embedded in a non-singular complex surface. Our sufficient condition is described by an arithmetical…

Complex Variables · Mathematics 2024-02-13 Satoshi Ogawa

We formulate and prove a periodic analog of Maxwell's theorem relating stressed planar frameworks and their liftings to polyhedral surfaces with spherical topology. We use our lifting theorem to prove deformation and rigidity-theoretic…

Metric Geometry · Mathematics 2015-01-16 Ciprian S. Borcea , Ileana Streinu

We study the rigidity of compact submanifolds of Riemannian manifolds of arbitrary codimension that satisfy a sharp pinching condition involving the norm of the second fundamental form and the mean curvature. Without assuming that the…

Differential Geometry · Mathematics 2026-03-25 Theodoros Vlachos

In this article we'll emphasize on two triangles and provide a vectorial proof of the fact that these triangles have the same orthocenter. This proof will further allow us to develop a vectorial proof of the Stevanovic's theorem relative to…

General Mathematics · Mathematics 2011-02-02 Ion Patrascu , Florentin Smarandache

We show that closed surfaces with minimal total absolute curvature in Cartan-Hadamard 3-manifolds bound flat convex bodies. This generalizes Chern-Lashof's theorem for surfaces in Euclidean space and solves a problem posed by Gromov in…

Differential Geometry · Mathematics 2026-04-29 Mohammad Ghomi , Joseph Ansel Hoisington , Matteo Raffaelli , John Ioannis Stavroulakis