系列の予測と強化学習 Bahdanau et al. An Actor-Critic Algorithm for Sequence Prediction arXiv:1607.07086 2016 Yu et al. SeqGAN: Sequence Generative Adversarial Nets with Policy Gradient AAAI 2017 Li et al. Adversarial Learning for Neural Dialogue Generation arXiv:1701.06547 2017