Optimizing Hierarchical Queries for the Attribution Reporting API. - Matthew Dawson; Badih Ghazi; Pritish Kamath; Kapil Kumar; Ravi Kumar 001; Bo Luan; Pasin Manurangsi; Nishanth Mundru; Harikesh Nair; Adam Sealfon; Shengyu Zhu 004 (AdKDD@KDD, 2023)