Inverse Approximation Theorems in the Spaces $S^{(p,q)}(\sigma^{m-1})$

The article continues the author's research, which began in  [1]–[3]. Inverse approximation theorems are established in the spaces $S^{(p,q)} (\sigma^{m-1})$, $m\ge 3$, including theorems of Bernstein–Stechkin–Timan type. The differential-difference characteristics of the elements of these spaces are given by the operators defined by the corresponding transformations of their Fourier-Laplace series.