About some linear operators (Q925444)

The author presents a general family of positive linear operators which include some known approximation processes. The construction follows the ideas of \textit{A. Jakimowski} and \textit{D. Leviatan} [Mathematica, Cluj 11(34), 97--103 (1969; Zbl 0188.36801)]. He presents theorems concerning rate of convergence and Voronovskaya-type theorems. Reviewer's remark: I think that some of the results are not as general as it appears in the paper. The author uses the usual first modulus of continuity. But on unbounded intervals this modulus is interesting only for bounded uniformly continuous functions and this class of functions is not considered on the paper.