Tensor products of Sobolev–Besov spaces and applications to approximation from the hyperbolic cross

Besov as well as Sobolev spaces of dominating mixed smoothness are shown to be tensor products of Besov and Sobolev spaces defined on RR. Using this we derive several useful characterizations from the one-dimensional case to the dd-dimensional situation. Finally, consequences for hyperbolic cross approximations, in particular for tensor product splines, are discussed.