“…This naturally gives rise to the Maximum Inner Product Search (MIPS) problem, which finds the vector in a set of n item vectors P ⊂ R d that has the largest inner product with a query (user) vector q ∈ R d , i.e., p * = arg max p∈P ⟨p, q⟩, as well as its extension kMIPS that finds k (k > 1) vectors with the largest inner products for recommending items to users. Due to its prominence in recommender systems, the kMIPS problem has attracted significant research interests, and numerous methods have been proposed to improve the search performance (Ram and Gray 2012;Koenigstein, Ram, and Shavitt 2012;Keivani, Sinha, and Ram 2018;Teflioudi and Gemulla 2017;Li et al 2017;Abuzaid et al 2019;Shrivastava and Li 2014;Neyshabur and Srebro 2015;Shrivastava and Li 2015;Huang et al 2018;Yan et al 2018;Ballard et al 2015;Yu et al 2017;Ding, Yu, and Hsieh 2019;Lorenzen and Pham 2020;Pham 2021;Shen et al 2015;Guo et al 2016;Dai et al 2020;Xiang et al 2021;Morozov and Babenko 2018;Tan et al 2019;Zhou et al 2019;Liu et al 2020;Tan et al 2021).…”