Paper detail

Higher regularity of homeomorphisms in the Hartman-Grobman theorem for semilinear evolution equations

Hein and Prüss [J. Differential Equations, 261(2016)4709-4727] presented a version of Hartman-Grobman type $C^{0}$ linearization result for semilinear hyperbolic evolution equations. They showed that the linearising map (homomorphism) and its inverse are Hölder continuous. An important question: is it possible to improve the regularity of the homomorphisms? In the present paper, we prove that if the mild solutions of semilinear system are bounded, then the regularity of the homomorphisms is Lipchitzian, but the inverse is merely Hölder continuous. We also give a generalized local linearization result in this paper. Finally, some applications end the paper. As pointed out by Backes [J. Differential Equations, 297 (2021) 536-574], even if the diffeomorphism $F$ is $C^{\infty}$, the homomorphism can fail to be locally Lipschitz. The homomorphisms are in general only locally Hölder continuous. However, by establishing two effective dichotomy integral inequalities, we prove that the conjugacy is Lipchitzian, but the inverse is Hölder continuous. Our result is the first one to observe the higher regularity of homomorphisms in the Hartman-Grobman theorem.