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This paper presents an analysis of the orientation selectivity properties of idealized models of complex cells in terms of affine quasi quadrature measures, which combine the responses of idealized models of simple cells in terms of affine…

Neurons and Cognition · Quantitative Biology 2025-08-26 Tony Lindeberg

We classify torsion-free real-analytic affine connections on compact oriented real-analytic surfaces which are locally homogeneous on a nontrivial open set, without being locally homogeneous on all of the surface. In particular, we prove…

Differential Geometry · Mathematics 2014-04-22 Sorin Dumitrescu , Adolfo Guillot

We investigate the geometry of the space of immersed closed curves equipped with reparametrization-invariant Riemannian metrics; the metrics we consider are Sobolev metrics of possible fractional order $q\in [0,\infty)$. We establish the…

Differential Geometry · Mathematics 2024-05-07 Martin Bauer , Patrick Heslin , Cy Maor

In this paper nontrivial Killing vector fields of constant length and corresponding flows on smooth complete Riemannian manifolds are investigated. It is proved that such a flow on symmetric space is free or induced by a free isometric…

Differential Geometry · Mathematics 2007-05-23 V. N. Berestovskii , Yu. G. Nikonorov

Affine varieties among all algebraic varieties have simple structures. For example, an affine variety does not contain any complete algebraic curve. In this paper we study affine related properties of strata of $k$-differentials on smooth…

Algebraic Geometry · Mathematics 2019-10-23 Dawei Chen

A complete set of mutually unbiased bases for a Hilbert space of dimension N is analogous in some respects to a certain finite geometric structure, namely, an affine plane. Another kind of quantum measurement, known as a symmetric…

Quantum Physics · Physics 2007-05-23 William K. Wootters

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

Our aim here is to investigate the holomorphic geometric structures on compact complex manifolds which may not be K\"ahler. We prove that holomorphic geometric structures of affine type on compact Calabi-Yau manifolds with polystable…

Differential Geometry · Mathematics 2016-02-16 Indranil Biswas , Sorin Dumitrescu

We prove that some symetric semi-riemannian manifolds do not admit a proper domain which is divisible by the action of a discrete group of isometries. In other words, if a closed semi-riemannian manifold is locally isometric to such a…

Differential Geometry · Mathematics 2013-07-15 Nicolas Tholozan

Let $\varphi\colon X\to Y$ be an affine continuous surjection between compact convex sets. Suppose that the canonical copy of the space of real-valued affine continuous functions on $Y$ in the space of real-valued affine continuous…

Functional Analysis · Mathematics 2016-09-05 Ondřej F. K. Kalenda , Jiří Spurný

Meshing of geometric domains having curved boundaries by affine simplices produces a polytopial approximation of those domains. The resulting error in the representation of the domain limits the accuracy of finite element methods based on…

Numerical Analysis · Mathematics 2018-02-09 James Cheung , Mauro Perego , Pavel Bochev , Max Gunzburger

The question whether a Riemannian manifold is geodesically connected can be studied from geometrical as well as variational methods, and accurate results can be obtained by using the associated distance and related properties of the…

Differential Geometry · Mathematics 2023-04-21 Miguel Sanchez

It is shown explicitly that when the characteristic vector field that defines a Godel-type metric is also a Killing vector, there always exist closed timelike or null curves in spacetimes described by such a metric. For these geometries,…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Reinaldo J. Gleiser , Metin Gurses , Atalay Karasu , Ozgur Sarioglu

This paper is concerned with the completeness (with respect to the centroaffine metric) of hyperbolic centroaffine hypersurfaces which are closed in the ambient vector space. We show that completeness holds under generic regularity…

Differential Geometry · Mathematics 2016-06-17 Vicente Cortés , Marc Nardmann , Stefan Suhr

We study the curvature of a manifold on which there can be defined a complex-valued submersive harmonic morphism with either, totally geodesic fibers or that is holomorphic with respect to a complex structure which is compatible with the…

Differential Geometry · Mathematics 2014-11-03 Jonas Nordström

Let G be a reductive algebraic group and H a closed subgroup of G. An affine embedding of the homogeneous space G/H is an affine G-variety with an open G-orbit isomorphic to G/H. We start with some basic properties of affine embeddings and…

Algebraic Geometry · Mathematics 2009-08-22 Ivan V. Arzhantsev

We give an affine proof of Feuerbach's theorem, by constructing an explicit affine map which takes the nine-point circle of any given Euclidean triangle to the incircle and fixes the Feuerbach point. The proof is shown to be valid in any…

Metric Geometry · Mathematics 2017-11-28 Patrick Morton

We prove that any affine ring $R$ over a field $k$ has full cosupport, i.e., the cosupport of $R$ is equal to ${\rm Spec}\, R$. Using this fact, we give a complete description of all terms in a minimal pure-injective resolution of $R$,…

Commutative Algebra · Mathematics 2019-09-23 Tsutomu Nakamura

In this work we study the general system of geodesic equations for the case of a massive particle moving on an arbitrary curved manifold. The investigation is carried out from the symmetry perspective. By exploiting the parametrization…

General Relativity and Quantum Cosmology · Physics 2019-06-05 N. Dimakis , Petros A. Terzis , T. Christodoulakis

The existence of at least two homogeneous geodesics in any homogeneous Finsler manifold was proved in a previous paper by the author. The examples of solvable Lie groups with invariant Finsler metric which admit just two homogeneous…

Differential Geometry · Mathematics 2021-04-14 Zdenek Dusek