Maillet type theorem and Gevrey regularity in time of solutions to nonlinear partial differential equations
Volume 97 / 2012
Abstract
We will consider the nonlinear partial differential equation \[ t^{\gamma}(\partial /\partial t)^mu =F(t,x,\{(\partial /\partial t)^j (\partial /\partial x)^{\alpha}u \}_{j+|\alpha| \leq L, j < m}) \tag*{(E)} \] (with $\gamma \geq 0$ and $1 \leq m \leq L$) and show the following two results: (1) (Maillet type theorem) if (E) has a formal solution it is in some formal Gevrey class, and (2) (Gevrey regularity in time) if (E) has a solution $u(t,x) \in C^{\infty}([0,T], {\mathcal E}^{\{\sigma \}}(V))$ it is in some Gevrey class also with respect to the time variable $t$. It will be explained that the mechanism of these two results are quite similar, but still there appears some difference between them which is very interesting to the author.