Since the pioneering work in machine translation (Sutskever et al., 2014), sequence-tosequence (SEQ2SEQ) models have led much recent progress in open-domain dialogue generation, especially single-turn generation where the input is a prompt and the output is a response.
sEQ2sEQ methods are known to favor universal responses, e.g., "I don't know what you are talking about" (sordoni et al., 2015;Li et al., 2016a).