Neumann problem in a disk for fourth-order improperly elliptic equations

Degenerate fourth order parabolic equations with Neumann boundary conditions

“…However, we conclude this introduction focusing on some works where the authors study a class of quite urgent problems of well posedness of so called general boundary value problems for higher order differential equations. In particular, in [8] and [9] the authors study a Neumann problem in a disk K ⊂ R 2 for fourth order improperly elliptic equations with constant complex coefficients and boundary conditions of this kind:…”