Interpolation of spaces of functions of positive smoothness on a domain (Q5896873)

Let \(G\) be a domain in \(\mathbb R^n\) satisfying the flexible horn condition. The paper deals with the real and the complex interpolation of the spaces \(B^s_{p,q} (G)\) and \(L^s_{p,q}(G) = F^s_{p,q} (G)\) where \(1\le p,q \le \infty\), \(m\in\mathbb N\) and \(s<m\), defined by optimal approximation by polynomials of degree \({m-1}\).