S. Dughmi. (2009)cite arxiv:0912.0322Comment: This revision corrects an error in definition 2.2, as well as provides additional intuition regarding the definitions of convex closure and concave closure.
A. Slivkins. (2019)cite arxiv:1904.07272Comment: The manuscript is complete, but comments are very welcome! To be published with Foundations and Trends in Machine Learning.