Remarks on a certain discrete generalization of Opial's inequality involving higher order differences (Q1916866)

In a paper published in J. Math. Anal. Appl. 167, No. 1, 98-110 (1992; Zbl 0821.26014), \textit{J.-D. Li} has given a certain discrete generalization of Opial's inequality involving functions and their higher-order differences. The result of Li grew out of an investigation of his similar result in the continuous case given in the same paper. In the present note, it is pointed out that the direct adaptation of the results from a continuous case to the discrete case is not always true and such an inequality given by Li reduces to the trivial one.