BLEU
BLEU score for the evaluation of MT Calculate BLEU score: Papineni, Kishore, Salim Roukos, Todd Ward, and Wei-Jing Zhu. 2002. "BLEU: a method for automatic evaluation of machine translation." In Proceedings of ACL. http://www.aclweb.org/anthology/P02-1040.pdf
deltaBLEU score for the evaluation of Response Generation Calculate BLEU score: Galley M, Brockett C, Sordoni A, et al. "deltaBLEU: A Discriminative Metric for Generation Tasks with Intrinsically Diverse Targets". arXiv preprint arXiv:1506.06863, 2015. http://arxiv.org/abs/1506.06863