AESOP: Paraphrase Generation with Adaptive Syntactic Control

We propose to control paraphrase generation with carefully chosen target syntactic structures to generate more proper and higher quality paraphrases. Our model, AESOP, leverages a pretrained language model and purposefully selected syntactical control via a retrieval-based selection module to generate fluent paraphrases. Experiments show that AE-SOP achieves state-of-the-art performances on semantic preservation and syntactic conformation on two benchmark datasets with groundtruth syntactic control from human-annotated exemplars. Moreover, with the retrieval-based target syntax selection module, AESOP generates paraphrases with even better qualities than the current best model using human-annotated target syntactic parses according to human evaluation. We further demonstrate the effectiveness of AESOP to improve classification models' robustness to syntactic perturbation by data augmentation on two GLUE tasks. AESOP What to say? How to guide paraphrasing? source parse (ROOT (S (NP ) (VP ) (. ) ) (ROOT (SBAR (IN ) (S ) (. ))) with the gold everything changes . the gold will change everything .