CLIFF: Contrastive Learning for Improving Faithfulness and Factuality in Abstractive Summarization Shuyang Cao author Lu Wang author 2021-11 text Proceedings of the 2021 Conference on Empirical Methods in Natural Language Processing Marie-Francine Moens editor Xuanjing Huang editor Lucia Specia editor Scott Wen-tau Yih editor Association for Computational Linguistics Online and Punta Cana, Dominican Republic conference publication cao-wang-2021-cliff 10.18653/v1/2021.emnlp-main.532 https://aclanthology.org/2021.emnlp-main.532/ 2021-11 6633 6649