## Reflection principles and kernels in $$\mathbb R^n_+$$ for the biharmonic and Stokes operators. Solutions in a large class of weighted Sobolev spaces.(English)Zbl 1193.35030

This paper deals with a class of Stokes systems in the half-space. The authors are interested in a kernel of an operator associated to this problem and symmetrically with the compatibility condition for the data. For this reason, an important part of this paper is devoted to the study of the reflection principles for the biharmonic and Stokes operators. After giving the weak formulation of the problem with the aim of getting the kernels in some distribution spaces, the authors state the main result of this paper. This deals with strong solutions and symmetrically very weak solutions. A central role in the proofs is played by adequate duality arguments.

### MSC:

 35J30 Higher-order elliptic equations 35D30 Weak solutions to PDEs 35J50 Variational methods for elliptic systems 35Q30 Navier-Stokes equations 76D07 Stokes and related (Oseen, etc.) flows 76D03 Existence, uniqueness, and regularity theory for incompressible viscous fluids