In some studies (e.g., [C. Zhang et al. in Proceedings of the 5th International Conference on Learning Representations, OpenReview.net, 2017]) deep learning, it is observed that overparametrized neural networks achieve a small testing error even when training almost zero. Despite numerous works toward understanding this so-called double-descent phenomenon [M. Belkin al., Proc. Natl. Acad. Sci. ...