About “Note that S is an unordered set” in the paper

[jjy91234]

Hi，thanks for your great job. But I have a question in this paper. I note the sentence in page4 “Note that S is an unordered set”. In my opinion, N has been pertumed in the KNN by the distance from the representative points，why not keep the same order in S? And we don‘t have to learn an X-conv to pertume the neighbors. Looking forward to your answer.