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A problem that is simple to state in the context of spherical geometry, and that seems rather interesting, appears to have been unexamined to date in the mathematical literature. The problem can also be recast as a problem in the real…

Metric Geometry · Mathematics 2023-07-18 Michael Q. Rieck

When considering fractional diffusion equation as model equation in analyzing anomalous diffusion processes, some important parameters in the model related to orders of the fractional derivatives, are often unknown and difficult to be…

Analysis of PDEs · Mathematics 2019-04-15 Zhiyuan Li , Yikan Liu , Masahiro Yamamoto

Understanding inhomogeneous and anisotropic fluid flows require mathematical and computational tools that are tailored to such flows and distinct from methods used to understand the canonical problem of homogeneous and isotropic turbulence.…

Fluid Dynamics · Physics 2023-01-05 J. B. Marston , S. M. Tobias

We present a new proof of the sphere covering inequality in the spirit of comparison geometry, and as a byproduct we find another sphere covering inequality which can be viewed as the dual of the original one. We also prove sphere covering…

Analysis of PDEs · Mathematics 2019-01-02 Changfeng Gui , Fengbo Hang , Amir Moradifam

We introduce an (equi-)affine invariant diffusion geometry by which surfaces that go through squeeze and shear transformations can still be properly analyzed. The definition of an affine invariant metric enables us to construct an invariant…

Computer Vision and Pattern Recognition · Computer Science 2010-12-30 Dan Raviv , Alexander M. Bronstein , Michael M. Bronstein , Ron Kimmel , Nir Sochen

Sharp reverse affine isoperimetric inequalities for asymmetric Wulff shapes and their polars are established, along with the characterization of all extremals. These new inequalities have as special cases previously obtained simplex…

Differential Geometry · Mathematics 2011-10-13 Franz E. Schuster , Manuel Weberndorfer

Based on the distinction between the covariant and contravariant metric tensor components in the framework of the affine geometry approach and also on the choice of the contravariant components, it was shown that a wide variety of third,…

Mathematical Physics · Physics 2009-11-06 Bogdan G. Dimitrov

Associated to every complete affine 3-manifold M with nonsolvable fundamental group is a noncompact hyperbolic surface S. We classify such complete affine structures when Sigma is homeomorphic to a three-holed sphere. In particular, for…

Differential Geometry · Mathematics 2011-07-12 Virginie Charette , Todd A. Drumm , William M. Goldman

In a recent paper, it was claimed that any homogeneous Finsler space of odd dimension admits a homogeneous geodesic through any point. For the proof, the algebraic method dealing with the reductive decomposition of the Lie algebra of the…

Differential Geometry · Mathematics 2019-03-11 Zdeněk Dušek

This work surveys classical and recent advances around the existence of exotic differentiable structures on spheres and its connection to stable homotopy theory.

Algebraic Topology · Mathematics 2010-01-27 Victor P. Snaith

Properties of the recently reported homogeneous Hilbert curves are deduced and reported. The nature of the affine transformations involved in the construction of the Hilbert curves is explored. The analytical representation of proper and…

Algebraic Geometry · Mathematics 2013-11-13 E. Estevez-Rams , I. Brito-Reyes

The main aim of the paper is to formulate and prove a result about the structure of double affine Hecke algebras which allows its two commutative subalgebras to play a symmetric role. This result is essential for the theory of intertwiners…

Quantum Algebra · Mathematics 2007-05-23 Bogdan Ion

Building on work of Furstenberg and Tzkoni, we introduce ${\bf r}$-flag affine quermassintegrals and their dual versions. These quantities generalize affine and dual affine quermassintegrals as averages on flag manifolds (where the…

Metric Geometry · Mathematics 2025-02-19 Susanna Dann , Grigoris Paouris , Peter Pivovarov

This paper is devoted to the complete classification of space curves under affine transformations in the view of Cartan's theorem. Spivak has introduced the method but has not found the invariants. Furthermore, for the first time, we…

Differential Geometry · Mathematics 2012-01-11 Mehdi Nadjafikhah , Ali Mahdipour Shirayeh

Natural objects can be subject to various transformations yet still preserve properties that we refer to as invariants. Here, we use definitions of affine invariant arclength for surfaces in R^3 in order to extend the set of existing…

Computer Vision and Pattern Recognition · Computer Science 2010-12-30 Dan Raviv , Alexander M. Bronstein , Michael M. Bronstein , Ron Kimmel , Nir Sochen

A posteriori residual and hierarchical upper bounds for the error estimates were proved when solving the hypersingular integral equation on the unit sphere by using the Galerkin method with spherical splines. Based on these a posteriori…

Numerical Analysis · Mathematics 2024-12-20 Duong Thanh Pham , Tung Le

The work develops further the theory of the following inversion problem, which plays the central role in the rapidly developing area of thermoacoustic tomography and has intimate connections with PDEs and integral geometry: {\it Reconstruct…

Classical Analysis and ODEs · Mathematics 2011-08-04 Yuri A. Antipov , Ricardo Estrada , Boris Rubin

An overview of some recent developments in inhomogeneous models is presented. As the volume and precision of cosmological data improves, it will become more and more essential to understand the non-linear behaviour of the Einstein field…

General Relativity and Quantum Cosmology · Physics 2010-01-06 Charles Hellaby

When considering fractional diffusion equation as model equation in analyzing anomalous diffusion processes, some important parameters in the model, for example, the orders of the fractional derivative or the source term, are often unknown,…

Analysis of PDEs · Mathematics 2019-04-15 Zhiyuan Li , Masahiro Yamamoto

Geometrical properties of holonomic and non holonomic varieties defined by the Pfaff equations connected with a first order systems of differential equations are studied. The Riemann extensions of affine connected spaces for investigation…

Differential Geometry · Mathematics 2007-05-23 Valerii Dryuma