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Conformal geometry is considered within a general relativistic framework. An invariant distant for proper time is defined and a parallel displacement is applied in the distorted space-time, modifying Einstein's equation appropriately. A…

General Relativity and Quantum Cosmology · Physics 2015-06-16 Edmund A. Chadwick , Timothy F. Hodgkinson , Graham S. McDonald

We obtain an approximate global stationary and axisymmetric solution of Einstein's equations which can be thought as a simple star model: a self-gravitating perfect fluid ball with a differential rotation motion pattern. Using the…

General Relativity and Quantum Cosmology · Physics 2017-10-04 A. Molina , E. Ruiz

This article is dedicated to solving the Einstein constraint equations with apparent horizon boundaries and freely specified mean curvature. The main novelty is that we study the conformal constraint equations assuming only low regularity.

General Relativity and Quantum Cosmology · Physics 2022-10-19 Jean-David Pailleron

A nonstationary spherically symmetric problem for conformal geometrodynamics equations is considered and general exact solutions in quadratures are obtained. Involvement of Weyl degrees of freedom allows us to consider the problem with…

General Relativity and Quantum Cosmology · Physics 2007-11-13 Mikhail V. Gorbatenko

A Cauchy-characteristic initial value problem for the Einstein-Klein-Gordon system with spherical symmetry is presented. Initial data are specified on the union of a space-like and null hypersurface. The development of the data is obtained…

General Relativity and Quantum Cosmology · Physics 2009-12-30 Roberto Go'mez , Pablo Laguna , Philippos Papadopoulos , Jeff Winicour

The Hamiltonian formulation of conformally invariant Weyl-squared higher derivative theory teaches us that conformal symmetry is expressed through particular first class constraints related to the absence of the three-metric determinant and…

General Relativity and Quantum Cosmology · Physics 2017-09-13 Branislav Nikolic

This paper is devoted to the study of a problem arising from a geometric context, namely the conformal deformation of a Riemannian metric to a scalar flat one having constant mean curvature on the boundary. By means of blow-up analysis…

Analysis of PDEs · Mathematics 2007-05-23 Veronica Felli , Mohameden Ould Ahmedou

There exist several ways of constructing general relativity from `first principles': Einstein's original derivation, Lovelock's results concerning the exceptional nature of the Einstein tensor from a mathematical perspective, and…

General Relativity and Quantum Cosmology · Physics 2017-09-19 Henrique Gomes

We describe conformally flat initial data, with explicitly given analytic extrinsic curvature solving the vacuum momentum constraints. They follow from a solution of Dain and Friedrich discovered in 2001. The cylindrically symmetric subcase…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Janusz Karkowski , Edward Malec

Gradient methods are widely used in optimization problems. In practice, while the smoothness parameter can be estimated utilizing techniques such as backtracking, estimating the strong convexity parameter remains a challenge; moreover, even…

Optimization and Control · Mathematics 2026-02-17 Xiaozhe Hu , Sara Pollock , Zhongqin Xue , Yunrong Zhu

As an efficient algorithm to solve the multi-view registration problem,the motion averaging (MA) algorithm has been extensively studied and many MA-based algorithms have been introduced. They aim at recovering global motions from relative…

Computer Vision and Pattern Recognition · Computer Science 2022-08-25 Yugeng Huang , Haitao Liu , Tian Huang

This research proposes a novel drift detection methodology for machine learning (ML) models based on the concept of ''deformation'' in the vector space representation of data. Recognizing that new data can act as forces stretching,…

Machine Learning · Computer Science 2024-11-06 Giancarlo Cobino , Simone Farci

We consider Lorentzian General Relativity in a cavity with a timelike boundary, with conformal boundary conditions and also a generalization of these boundary conditions. We focus on the linearized gravitational dynamics about the static…

General Relativity and Quantum Cosmology · Physics 2025-07-04 Xiaoyi Liu , Harvey S. Reall , Jorge E. Santos , Toby Wiseman

We treat the calculation of gravitational radiation using the mixed timelike-null initial value formulation of general relativity. The determination of an exterior radiative solution is based on boundary values on a timelike worldtube…

General Relativity and Quantum Cosmology · Physics 2007-05-23 N. Bishop , R. Gomez , L. Lehner , J. Winicour

The curvature regularities are well-known for providing strong priors in the continuity of edges, which have been applied to a wide range of applications in image processing and computer vision. However, these models are usually non-convex,…

Numerical Analysis · Mathematics 2019-12-03 Qiuxiang Zhong , Ke Yin , Yuping Duan

Computational techniques which establish the stability of an evolution-boundary algorithm for a model wave equation with shift are incorporated into a well-posed version of the initial-boundary value problem for gravitational theory in…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Maria C. Babiuc , Bela Szilagyi , Jeffrey Winicour

This paper presents both a numerical method for general relativity and an application of that method. The method involves the use of harmonic coordinates in a 3+1 code to evolve the Einstein equations with scalar field matter. In such…

General Relativity and Quantum Cosmology · Physics 2011-04-21 David Garfinkle

We consider the metrics of the General Relativity, whose energy-momentum tensor has a bounded support where it is continuous except for a finite step across the corresponding boundary surface. As a consequence, the first derivative of the…

General Relativity and Quantum Cosmology · Physics 2019-10-18 Ramon Lapiedra , Juan Antonio Morales-Lladosa

We consider gravitational field equations which are Einstein equations written in terms of embedding coordinates in some higher dimensional Minkowski space. Our main focus is to address some tricky issues relating to the Cauchy problem and…

General Relativity and Quantum Cosmology · Physics 2014-05-27 Steven Willison

The generalized harmonic equations of general relativity are written in 3+1 form. The result is a system of partial differential equations with first order time and second order space derivatives for the spatial metric, extrinsic curvature,…

General Relativity and Quantum Cosmology · Physics 2013-05-29 J. David Brown