We are very grateful to the reviewers for their helpful feedback and suggestions, and are pleased to have received a

Neural Information Processing Systems 

Our responses to the main concerns are given as follows. Section 4.4 for a related discussion and generalizations to non-unit norms. We would be happy to move some of the less central corollaries (e.g., Sections 4.2 and 4.5) to the We will also correct the typo in Line 202.