@inproceedings{xiao-etal-2026-revisiting,
    title = "Revisiting Self-Play Preference Optimization: On the Role of Prompt Difficulty",
    author = "Xiao, Yao  and
      Kim, Jung-jae  and
      Lee, Roy Ka-Wei  and
      Bing, Lidong",
    editor = "Liakata, Maria  and
      Moreira, Viviane P.  and
      Zhang, Jiajun  and
      Jurgens, David",
    booktitle = "Findings of the {A}ssociation for {C}omputational {L}inguistics: {ACL} 2026",
    month = jul,
    year = "2026",
    address = "San Diego, California, United States",
    publisher = "Association for Computational Linguistics",
    url = "https://preview.aclanthology.org/ingest-acl/2026.findings-acl.144/",
    pages = "2968--2980",
    ISBN = "979-8-89176-395-1"
}