A common linguistic definition of paraphrase is that two sentences are paraphrases of each other if they mutually entail each other.

• Wieting & Gimpel 2017 - ParaNMT-50M: Pushing the Limits of Paraphrastic Sentence Embeddings with Millions of Machine Translations

• Microsoft Research Paraphrase Corpus: Dataset, paper: Dolan & Brockett 2003 - Automatically Constructing a Corpus of Sentential Paraphrases
• PAWS: Zhang et al 2019 - PAWS: Paraphrase Adversaries from Word Scrambling
• PAWS-X: Yang et al 2019 - PAWS-X: A Cross-lingual Adversarial Dataset for Paraphrase Identification

• Google's T5 fine-tuned on Quora question pair dataset for Question Paraphrasing task

Task: convert a question (and possibly the answer) into a statement. Not quite paraphrase exactly, but related.

• https://github.com/SunnyWay/question_to_statement
• Demszky et al 2018 - Transforming Question Answering Datasets Into Natural Language Inference Datasets. dataset

Related pages: Question Generation

• Gan & Ng 2019 - Improving the Robustness of Question Answering Systems to Question Paraphrasing

• Entailment
• Semantics