ON APPROXIMATION OF FUNCTIONS BY PRODUCT OPERATORS.

In the present paper, two quite new reults on the degree of approximation of a function f belonging to the class Lip(α, r), 1 ≤ r < ∞ and the weighted class W(Lr, ξ(t)), 1 ≤ r < ⊂ by (C, 2)(E, 1) product operators have been obtained. The results obtained in the present paper generalize various known results on single operators. [ABSTRACT FROM AUTHOR]