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An intrinsic local time in Geometrodynamics is obtained with using a scaled Dirac's mapping. By addition of a background metric, one can construct a scalar field. It is suitable to play a role of intrinsic time. Cauchy problem was…

General Relativity and Quantum Cosmology · Physics 2016-07-01 Alexander Pavlov

We consider the $L^2$-boundedness of the solution itself of the Cauchy problem for wave equations with time-dependent wave speeds. We treat it in the one-dimensional Euclidean space. To study these, we adopt a simple multiplier method by…

Analysis of PDEs · Mathematics 2023-09-13 Ryo Ikehata

The exponential map that characterises the flows of vector fields is the key in understanding the basic structural attributes of control systems in geometric control theory. However, this map does not exists due to the lack of completeness…

Differential Geometry · Mathematics 2022-02-11 Yanlei Zhang

In this thesis the generally covariant locality principle for bosonic free fields has been thoroughly analyzed devoting particular attention to the case of spin 1 fields on curved spacetimes (Proca and Maxwell fields). This has been…

Mathematical Physics · Physics 2011-11-29 Marco Benini

In this paper, we study the Bakry-\'Emery Ricci flow on finite graphs. Our main result is the local existence and uniqueness of solutions to the Ricci flow. We prove the long-time convergence or finite-time blow up for the Bakry-\'Emery…

Differential Geometry · Mathematics 2024-02-13 Bobo Hua , Yong Lin , Tao Wang

In this contribution, we study spacetimes of cosmological interest, without making any symmetry assumptions. We prove a rigid Hawking singularity theorem for positive cosmological constant, which sharpens known results. In particular, it…

General Relativity and Quantum Cosmology · Physics 2026-02-16 Gregory J. Galloway , Leonardo García-Heveling

In this article, we investigate the geometry of static perfect fluid space-time on compact manifolds with boundary. We use the generalized Reilly's formula to establish a geometric inequality for a static perfect fluid space-time involving…

Differential Geometry · Mathematics 2023-09-08 Johnatan Costa , Rafael Diógenes , Neilha Pinheiro , Ernani Ribeiro

In this paper, we study the wave equation on infinite graphs. On one hand, in contrast to the wave equation on manifolds, we construct an example for the non-uniqueness for the Cauchy problem of the wave equation on graphs. On the other…

Analysis of PDEs · Mathematics 2023-11-17 Fengwen Han , Bobo Hua

In the time evolution of fluids, the topologies of fluids can be changed by the creations and annihilations of singular points and by switching combinatorial structures of separatrices. In this paper, to describe the possible generic time…

Dynamical Systems · Mathematics 2023-07-07 Tomoo Yokoyama

In this paper, we consider the Cauchy problem for pressureless gases in two space dimensions with generic smooth initial data (density and velocity). These equations give rise to singular curves, where the mass has positive density…

Analysis of PDEs · Mathematics 2023-07-24 Alberto Bressan , Geng Chen , Shoujun Huang

We deal with the Cauchy problem for multi-dimensional scalar conservation laws, where the fluxes and the source terms can be discontinuous functions of the unknown. The main novelty of the paper is the introduction of a~kinetic formulation…

Analysis of PDEs · Mathematics 2016-06-22 Miroslav Bulíček , Piotr Gwiazda , Agnieszka Świerczewska-Gwiazda

In 1981, Frisch and Morf [1] postulated the existence of complex singularities in solutions of Navier-Stokes equations. Present progress on this conjecture is hindered by the computational burden involved in simulations of the Euler…

In this investigation we revisit the concept of "effective free surfaces" arising in the solution of the time-averaged fluid dynamics equations in the presence of free boundaries. This work is motivated by applications of the optimization…

Fluid Dynamics · Physics 2012-09-04 R. Yapalparvi , B. Protas

Close insight into mathematical and conceptual structure of classical field theories shows serious inconsistencies in their common basis. In other words, we claim in this work to have come across two severe mathematical blunders in the very…

Classical Physics · Physics 2016-09-08 R. Smirnov-Rueda

An existence and uniqueness result, up to fattening, for crystalline mean curvature flows with forcing and arbitrary (convex) mobilities, is proven. This is achieved by introducing a new notion of solution to the corresponding level set…

Analysis of PDEs · Mathematics 2017-02-13 Antonin Chambolle , Massimiliano Morini , Matteo Novaga , Marcello Ponsiglione

We collect and present in a unified way several results in recent years about the elastic flow of curves and networks, trying to draw the state of the art of the subject. In particular, we give a complete proof of global existence and…

Analysis of PDEs · Mathematics 2023-03-30 Carlo Mantegazza , Alessandra Pluda , Marco Pozzetta

A nonlocal curvature flow is introduced to evolve locally convex curves in the plane. It is proved that this flow with any initial locally convex curve has a global solution, keeping the local convexity and the elastic energy of the…

Differential Geometry · Mathematics 2024-04-09 Laiyuan Gao , Horst Martini , Deyan Zhang

Recently Burrage, de Rham, Heisenberg and Tolley have constructed eternal, classical solutions with closed timelike curves (CTCs) in a Galileon model coupled to an auxiliary scalar field. These theories contain at least two distinct metrics…

High Energy Physics - Theory · Physics 2012-11-20 Jarah Evslin

We prove that the 3-D free-surface incompressible Euler equations with regular initial geometries and velocity fields have solutions which can form a finite-time "splash" (or "splat") singularity first introduced in [9], wherein the…

Analysis of PDEs · Mathematics 2015-06-03 Daniel Coutand , Steve Shkoller

We generalize a bi-Lipschitz extension result of David and Semmes from Euclidean spaces to complete metric measure spaces with controlled geometry (Ahlfors regularity and supporting a Poincar\'e inequality). In particular, we find sharp…

Metric Geometry · Mathematics 2024-03-14 Jacob Honeycutt , Vyron Vellis , Scott Zimmerman