To define an exact metric, we reference the burgeoning field of research aimed at measuring semantic textual similarity (STS) between two sentences (Le and Mikolov, 2014;Pham et al., 2015;Wieting et al., 2016;Hill et al., 2016;Conneau et al., 2017;Pagliardini et al., 2017).
we start with the method of Wieting and Gimpel (2018), which learns paraphrastic sentence representations using a contrastive loss and a parallel corpus induced by backtranslating bitext.