摘要：The paper [1] has one main theorem, namely Theorem 3. In the lastline of the theorem’s proof it is assumed that the set S ∗ is independent.This assumption is not necessarily correct, and it is not possible to fixit, since the set S is randomly chosen. This mistake makes the mainresult of the paper wrong.At the request of the author (Received October 21, 2019), the articlehas been retracted.
