The author takes an array , , such that for each , exists for which , (the reviewer could not find where the latter assumption is used or even mentioned again in the paper). And he takes a family of nonnegative functions , , , satisfying
and such that there exists a sequence of positive functions , for which
He defines the operators
for all functions defined on for which the sums converge. Special cases are the Szász-Mirakyan and the Baskakov operators. (Note that in the paper there is a mistake in the definition of the Baskakov operators.) The author investigates the properties of the th central moment of , namely,
not noticing that nothing in his assumptions guarantees the convergence of the infinite sum for . Thus without additional assumptions Lemma 1 and hence Theorem 1, are invalid. Assuming that we add the appropriate assumptions above, the reviewer fails to see the proof of Lemma 2 since the author indicates nothing about the behavior of that is needed in his induction step. In addition, the reviewer wonders why Lemma 2 “might be of interest in its own right”. The methods of proof are completely standard, notwithstanding the above comments.