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Random projections offer an appealing and flexible approach to a wide range of large-scale statistical problems. They are particularly useful in high-dimensional settings, where we have many covariates recorded for each observation. In…

Methodology · Statistics 2019-11-26 Timothy I. Cannings

This article provides a new perspective on the geometry of a projective line, which helps clarify and illuminate some classical results about projective plane. As part of the same train of ideas, the article also provides a proof of the…

General Mathematics · Mathematics 2022-05-11 Nicholas Phat Nguyen

Classification theory and the study of projective varieties which are covered by rational curves of minimal degrees naturally leads to the study of families of singular rational curves. Since families of arbitrarily singular curves are hard…

Algebraic Geometry · Mathematics 2007-05-23 Stefan Kebekus

Let $P$ be a set of points and $L$ a set of lines in the (extended) Euclidean plane, and $I \subseteq P\times L$, where $i =(p,l) \in I$ means that point $p$ and line $l$ are incident. The incidences can be interpreted as quadratic…

The purpose of this paper is to present projective geometry in a synthetic, visual and intuitive style through the central notion of harmonicity which leads to harmonic curves. This presentation includes new results, unpublished proofs of…

History and Overview · Mathematics 2024-10-23 José Luis Abreu , Javier Bracho

Formerly the geometry was based on shapes, but since the last centuries this founding mathematical science deals with transformations, projections and mappings. Projective geometry identifies a line with a single point, like the perspective…

Dynamical Systems · Mathematics 2024-05-17 A. Hossain , Md. N. Akhtar , M. A. Navascués

A finite projective plane, or more generally a finite linear space, has an associated incidence complex that gives rise to two natural algebras: the Stanley-Reisner ring $R/I_\Lambda$ and the inverse system algebra $R/I_\Delta$. We give a…

Commutative Algebra · Mathematics 2016-08-03 David Cook , Juan Migliore , Uwe Nagel , Fabrizio Zanello

This paper combines two classical theories, namely metric projective differential geometry and superintegrability. We study superintegrable systems on 2-dimensional geometries that share the same geodesics, viewed as unparametrized curves.…

Differential Geometry · Mathematics 2020-02-13 Andreas Vollmer

A classical result asserts that the complex projective plane modulo complex conjugation is the 4-dimensional sphere. We generalize this result in two directions by considering the projective planes over the normed real division algebras and…

Differential Geometry · Mathematics 2007-05-23 Michael Atiyah , Jurgen Berndt

A parallelogram is conformally inscribed in four lines in the plane if it is inscribed in a scaled copy of the configuration of four lines. We describe the geometry of the three-dimensional Euclidean space whose points are the…

Metric Geometry · Mathematics 2021-08-04 Bruce Olberding , Elaine A. Walker

A new type of sectional curvature is introduced. The notion is purely algebraic and can be located in linear algebra as well as in differential geometry.

Differential Geometry · Mathematics 2015-04-07 Barbara Opozda

We define the notion of "projective" multiresolution analyses, for which, by definition, the initial space corresponds to a finitely generated projective module over the algebra $C(\btn)$ of continuous complex-valued functions on an…

Functional Analysis · Mathematics 2007-05-23 Judith A. Packer , Marc A. Rieffel

A pseudo-triangle is a simple polygon with three convex vertices, and a pseudo-triangulation is a face-to-face tiling of a planar region into pseudo-triangles. Pseudo-triangulations appear as data structures in computational geometry, as…

Combinatorics · Mathematics 2015-02-18 Guenter Rote , Francisco Santos , Ileana Streinu

Given a real vector space V of finite dimension, together with a particular homogeneous field of bivectors that we call a "field of projective forces", we define a law of dynamics such that the position of the particle is a "ray" i.e. a…

Mathematical Physics · Physics 2015-11-24 Alain Albouy

In this paper, we present a mathematical model for the angular projection of a rectangular arrangement of points in a grid. This simple, yet interesting problem, has both a scholarly value and applications for data extraction techniques to…

General Physics · Physics 2015-02-05 Ashmeet Singh

Paravectors just like integers have a ring structure. By introducing an integrated product we get geometric properties which make paravectors similar to vectors. The concepts of parallelism, perpendicularity and the angle are conceptually…

Rings and Algebras · Mathematics 2016-05-10 Radomański Józef

The method of alternating projections involves orthogonally projecting an element of a Hilbert space onto a collection of closed subspaces. It is known that the resulting sequence always converges in norm if the projections are taken…

Functional Analysis · Mathematics 2018-09-18 Omer Ginat

Tensor diagrams are a handy way to depict complicated relationships between objects in projective geometry. One of the simpler ones takes two copies of a $3\times 3$ matrix and computes its adjugate. In this paper, we give a geometric…

Algebraic Geometry · Mathematics 2023-02-09 Bernhard Odin Werner

We investigate when the tangent bundle of a projective manifold has a non-trivial first order (or positive-dimensional) deformation. This leads to a new conjectural characterization of the complex projective space.

Algebraic Geometry · Mathematics 2020-07-20 Thomas Peternell

This monograph is on convex real projective structures on strongly tame n-orbifolds with some appropriate conditions on ends.

Geometric Topology · Mathematics 2025-09-03 Suhyoung Choi