Preliminaries
摘要
The second chapter is devoted to a few basic notions and results that are needed throughout the book, including: Lipschitz domains, non-tangential maximal and limit operators, Sobolev, Bessel potential, and Besov spaces on \(\mathbb R^{n}\) , the (Gagliardo) boundary traces, and various types of conormal derivatives. We also introduce the Brinkman system.