Generating text is a core part of many NLP tasks such as image captioning (Lin et al., 2014), opendomain dialogue , story generation (Roemmele, 2016), and summarization (Nallapati et al., 2016).
proper evaluation of natural language generation has proven difficult (Liu et al., 2016;Novikova et al., 2017;Chaganty et al., 2018).