C2AL: Cohort-Contrastive Auxiliary Learning for Large-scale Recommendation Systems. - Mertcan Cokbas; Ziteng Liu; Zeyi Tao; Elder Veliz; Qin Huang; Ellie Wen; Huayu Li; Qiang Jin; Murat Duman; Benjamin Au; Guy Lebanon; Sagar Chordia; et al. (CoRR, 2025)