Learning to Tokenize for Generative Retrieval - Sun, Weiwei; Yan, Lingyong; Chen, Zheng; Wang, Shuaiqiang; Zhu, Haichao; Ren, Pengjie; Chen, Zhumin; Yin, Dawei; Rijke, Maarten; Ren, Zhaochun (Advances in Neural Information Processing Systems, 2023)