RecIS: Sparse to Dense, A Unified Training Framework for Recommendation Models. - Hua Zong; Qingtao Zeng; Zhengxiong Zhou; Zhihua Han; Zhensong Yan; Mingjie Liu; Hechen Sun; Jiawei Liu; Yiwen Hu; Qi Wang; YiHan Xian; Wenjie Guo; et al. (CoRR, 2025)