The Overdetermined Cauchy Problem for $\omega$-ultradifferentiable Functions

In this paper we study the Cauchy problem for overdetermined systems of linear partial differential operators with constant coefficients in some spaces of $\omega$-ultradifferentiable functions in the sense of Braun, Meise and Taylor, for non-quasianalytic weight functions $\omega$. We show that existence of solutions of the Cauchy problem is equivalent to the validity of a Phragm\'en-Lindel\"of principle for entire and plurisubharmonic functions on some irreducible affine algebraic varieties.