SPECTRA: Sparse Structured Text Rationalization Nuno M Guerreiro author André F T Martins 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 guerreiro-martins-2021-spectra 10.18653/v1/2021.emnlp-main.525 https://aclanthology.org/2021.emnlp-main.525/ 2021-11 6534 6550