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The Cauchy problem for wave equations with non Lipschitz coefficients; Application to continuation of solutions of some nonlinear wave equations

Ferruccio Colombini, Guy Métivier (2008)

Annales scientifiques de l'École Normale Supérieure

In this paper we study the Cauchy problem for second order strictly hyperbolic operators of the form L u : = j , k = 0 n y j ( a j , k y k u ) + j = 0 n { b j y j u + y j ( c j u ) } + d u = f , when the coefficients of the principal part are not Lipschitz continuous, but only “Log-Lipschitz” with respect to all the variables. This class of equation is invariant under changes of variables and therefore suitable for a local analysis. In particular, we show local existence, local uniqueness and finite speed of propagation for the noncharacteristic Cauchy problem. This provides an invariant...

The FBI transform, operators with nonsmooth coefficients and the nonlinear wave equation

Daniel Tataru (1999)

Journées équations aux dérivées partielles

The aim of this work is threefold. First we set up a calculus for partial differential operators with nonsmooth coefficients which is based on the FBI (Fourier-Bros-Iagolnitzer) transform. Then, using this calculus, we prove a weaker version of the Strichartz estimates for second order hyperbolic equations with nonsmooth coefficients. Finally, we apply these new Strichartz estimates to second order nonlinear hyperbolic equations and improve the local theory, i.e. prove local well-posedness for initial...

The wave map problem. Small data critical regularity

Igor Rodnianski (2005/2006)

Séminaire Bourbaki

The paper provides a description of the wave map problem with a specific focus on the breakthrough work of T. Tao which showed that a wave map, a dynamic lorentzian analog of a harmonic map, from Minkowski space into a sphere with smooth initial data and a small critical Sobolev norm exists globally in time and remains smooth. When the dimension of the base Minkowski space is ( 2 + 1 ) , the critical norm coincides with energy, the only manifestly conserved quantity in this (lagrangian) theory. As a consequence,...

Time-periodic solutions of a quasilinear beam equation via accelerated convergence methods

Eduard Feireisl (1988)

Aplikace matematiky

The author investigates time-periodic solutions of the quasilinear beam equation with the help of accelerated convergence methods. Using the Newton iteration scheme, the problem is approximated by a sequence of linear equations solved via the Galerkin method. The derivatiove loss inherent to this kind of problems is compensated by taking advantage of smoothing operators.

Currently displaying 421 – 440 of 475