Before revision:  For comparison, three existing metrics, Bilingual Evaluation Understudy (BLEU) verse self-BLEU, language model score verse reverse language model score, Fr'chet Embedding Distance (FED), together with the proposed DD, are used to evaluate two popular generative models of LSTM and GPT-2 on both syntactic and real data.
After revision:  For comparison, three existing metrics, Bilingual Evaluation Understudy (BLEU) verse self-BLEU, language model score verse reverse language model score, and Fr\'{e with the proposed DD, are used to evaluate two popular generative models of LSTM and GPT-2 on both syntactic and real data.