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We perform a phase space analysis of a generalized modified gravity theory with nonminimally coupling between geometry and matter. We apply the dynamical system approach to this generalized model and find that in the cosmological context,…

General Relativity and Quantum Cosmology · Physics 2016-05-17 Rui An , Xiaodong Xu , Bin Wang , Yungui Gong

Timelike and null hypersurfaces in the degenerate space-times in the Ashtekar theory are defined in the light of the degenerate causal structure proposed by Matschull. Using the new definition of null hypersufaces, the conjecture that the…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Yongge Ma , Canbin Liang

We develop a new formalism for the treatment of gravitational backreaction in the cosmological setting. The approach is inspired by projective techniques in non-equilibrium statistical mechanics. We employ group-averaging with respect to…

General Relativity and Quantum Cosmology · Physics 2009-11-06 Charis Anastopoulos

A very small amount of K\"ahler algebra (i.e. Clifford algebra of differential forms) in the real plane makes x + ydxdy emerge as a factor between the differentials of the Cartesian and polar coordinates, largely replacing the concept of…

General Mathematics · Mathematics 2012-05-22 Jose G. Vargas

Identifying an appropriate set of ``observables'' is a nontrivial task for most approaches to quantum gravity. We describe how it may be accomplished in the context of a recently proposed family of stochastic (but classical) dynamical laws…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Graham Brightwell , H. Fay Dowker , Joe Henson , Raquel S. Garcia , Rafael D. Sorkin

We investigate the effective dynamics of a spatially flat FLRW universe coupled to a massless scalar field by applying the improved generalized uncertainty principle (GUP)-inspired deformations to the algebra of Ashtekar-Barbero variables.…

General Relativity and Quantum Cosmology · Physics 2026-04-09 Saeed Rastgoo , Wilfredo Yupanqui

In this article we propose a dynamic approach to complex vector reconstruction in the context of quantum tomography. There are two underlying assumptions behind our reasoning. The first one claims that the evolution of a d-level pure…

Quantum Physics · Physics 2020-07-03 Artur Czerwiński

We present a Hilbert space perspective to homogenization of standard linear evolutionary boundary value problems in mathematical physics and provide a unified treatment for (non-)periodic homogenization problems in thermodynamics,…

Analysis of PDEs · Mathematics 2016-03-08 Marcus Waurick

We apply the consistent discretization scheme to general relativity particularized to the Gowdy space-times. This is the first time the framework has been applied in detail in a non-linear generally-covariant gravitational situation with…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Rodolfo Gambini , Marcelo Ponce , Jorge Pullin

Here, we introduce the Directional Quantum Evolution Theory (DQET), a covariant reformulation of quantum mechanics where evolution takes place along a four-vector-defined arbitrary timelike direction. This method restores space-time…

General Physics · Physics 2025-08-26 Tarek Yehia

We extend the definition of generalized coherent states to include the case of time-dependent dispersion. We introduce a suitable operator providing displacement and dynamical rescaling from an arbitrary ground state. As a consequence,…

Quantum Physics · Physics 2007-05-23 Salvatore De Martino , Silvio De Siena , Fabrizio Illuminati

On a manifold or a closed subset of a Euclidean vector space, a retraction enables to move in the direction of a tangent vector while staying on the set. Retractions are a versatile tool to perform computational tasks such as optimization,…

Optimization and Control · Mathematics 2024-11-18 Guillaume Olikier

Global constraints proved themselves to be an efficient tool for modelling and solving large-scale real-life combinatorial problems. They encapsulate a set of binary constraints and using global reasoning about this set they filter the…

Programming Languages · Computer Science 2007-05-23 Roman Bartak

We propose a solution to the problem of time for systems with a single global Hamiltonian constraint. Our solution stems from the observation that, for these theories, conventional gauge theory methods fail to capture the full classical…

General Relativity and Quantum Cosmology · Physics 2015-05-30 Sean Gryb , Karim Thebault

In this paper, we study the convergence for solutions to a sequence of (possibly degenerate) stochastic differential equations with jumps, when the coefficients converge in some appropriate sense. Our main tools are the superposition…

Probability · Mathematics 2025-06-18 Huijie Qiao

A generalized Black-Scholes equation is considered on the semi-axis. It is transformed on the interval (0,1) in order to make the computational domain finite. The new parabolic operator degenerates at the both ends of the interval and we…

Numerical Analysis · Mathematics 2013-07-02 Radoslav Valkov

We give a proposal to generalize the concept of the differential equations on time scales, such that they can be more appropriate for the analysis of real world problems, and give more opportunities to increase the theoretical depth of…

Dynamical Systems · Mathematics 2010-10-12 Marat Akhmet , Mehmet Turan

We derive a generalized deviation equation in Riemann-Cartan spacetime. The equation describes the dynamics of the connecting vector which links events on two general adjacent world lines. Our result is valid for any theory in a…

General Relativity and Quantum Cosmology · Physics 2018-06-05 Dirk Puetzfeld , Yuri N. Obukhov

We use differential equations based approaches to provide some {\it \textbf{physics}} insights into analyzing the dynamics of popular optimization algorithms in machine learning. In particular, we study gradient descent, proximal gradient…

Machine Learning · Computer Science 2018-10-26 Lin F. Yang , R. Arora , V. Braverman , Tuo Zhao

In this paper, we study an ordinary differential equation with a degenerate global attractor at the origin, to which we add a white noise with a small parameter that regulates its intensity. Under general conditions, for any fixed…

Probability · Mathematics 2025-05-27 Gerardo Barrera , Conrado da Costa , Milton Jara