The aim of the present paper is to extent the well known fundamental estimates (w.r.t. the $L^2$-norm) for weak solutions of a linear elliptic system with constant coefficients: \[ \sum_{ j= 1}^ N \sum_{\mid \alpha\mid,\mid ...

Let $\Omega$ be an exterior domain in $\R^n\,(n=2,3,4)$ , with boundary being not necessarily smooth. For any initial velocity ${\bf u}_0\in L^2(\Omega)^n$ such that $\nabla\cdot {\bf u}_0=0$ (in sense of distribution) and ...

In der vorliegenden Arbeit untersuchen wir schwache Lösungen, die zu einem geeigneten Sobolevraum gehören, q-elliptischer und parabolischer Systeme partieller Differentialgleichungen auf deren Regularität für den Fall 1