Block Toeplitz operators with frequency-modulated semi-almost periodic symbols
Let \(b\in L^\infty_{n\times n} (\mathbb{R})\) be in one of the classes of oscillating \(n\times n\) matrix functions (periodic, almost-periodic or semi-almost periodic ) and \(T_{b(x)}\) be a Toeplitz operator in the Hardy space \(H^2_n (\mathbb{R})\). The authors give conditions on an orientation-preserving homomorphism \(\alpha:\mathbb{R}\to \mathbb{R}\) so that the Toeplitz operator \(T_{b[\alpha(x)]}\) is \(\Phi_\pm\), Fredholm or normal solvable if \(T_{b(x)}\) is also of the the same kind.
scientific article; zbMATH DE number 1930098