Reviews: Globally Optimal Learning for Structured Elliptical Losses

Lemma 1) is incrementally built on previous work. Based on related work, it's hard to contextualize their work in the existing literature. The readers may have the following important questions. A clear explanation is needed for this. This work is significant in that they provide optimality proof that leads to more efficient optimization method for a wide range of robust elliptical losses including Gaussian, Generalized Gaussian, Huber, etc.