The ACM Multimedia 2021 paper list was recently announced. One paper from RUC Gaoling School of Artificial Intelligence was accepted. ACM Multimedia was initiated by the Association for Computing Machinery (ACM), and it is the most influential international conference in the field of multimedia processing, analysis and computing. Title: General Approximate Cross Validation for Model Selection: Supervised, Semi-supervised and Pairwise Learning Authors: ZHU Bowei, LIU Yong Corresponding Author: LIU Yong