Two-Sided Estimates of the -Functional for Spaces of Functions of Generalized Bounded Variation

A two-sided estimate is proposed for the -functional of the pair , where is the space of functions of generalized bounded variation constructed from a symmetric sequence space . The application of this estimate to various sequence spaces yields new interpolation theorems for spaces of finite Wiener–Young -variation, of finite Waterman -variation, of bounded modulus of variation in the sense of Chanturiya, etc.