“…In specific, they have treated the retrieved knowledge, document, or passage as an unobserved latent variable and adapt latent variable modeling based on approximated marginalization (e.g. top-k) Huang et al, 2021;Cai et al, 2023;Guu et al, 2020), reinforcement learning (Zhao et al, 2020;Zhang et al, 2022;Chen et al, 2022; or variational methods (Zhan et al, 2021;Paranjape et al, 2022;Lian et al, 2019;Kim et al, 2020;Chen et al, 2020;Xu et al, 2023). However, joint training of the retriever along with the generator under this latent variable modeling has some restrictions in utilizing the retriever.…”