Greibach normal form transformation, revisited

Author(s):  
Robert Koch ◽  
Norbert Blum
1999 ◽  
Vol 150 (1) ◽  
pp. 112-118 ◽  
Author(s):  
Norbert Blum ◽  
Robert Koch

Author(s):  
Pietro Baldi ◽  
Emanuele Haus

Abstract Consider the Kirchhoff equation $$\begin{aligned} \partial _{tt} u - \Delta u \Big ( 1 + \int _{\mathbb {T}^d} |\nabla u|^2 \Big ) = 0 \end{aligned}$$ ∂ tt u - Δ u ( 1 + ∫ T d | ∇ u | 2 ) = 0 on the d-dimensional torus $$\mathbb {T}^d$$ T d . In a previous paper we proved that, after a first step of quasilinear normal form, the resonant cubic terms show an integrable behavior, namely they give no contribution to the energy estimates. This leads to the question whether the same structure also emerges at the next steps of normal form. In this paper, we perform the second step and give a negative answer to the previous question: the quintic resonant terms give a nonzero contribution to the energy estimates. This is not only a formal calculation, as we prove that the normal form transformation is bounded between Sobolev spaces.


1993 ◽  
Vol 179 (6) ◽  
pp. 398-402 ◽  
Author(s):  
S.T.R. de Pinho ◽  
R.F.S. Andrade

Sign in / Sign up

Export Citation Format

Share Document