“…Recent success in deep learning, especially encoder-decoder models (Sutskever et al, 2014;Bahdanau et al, 2015), has dramatically improved the performance of various text-generation tasks, such as translation (Johnson et al, 2017), summarization (Ayana et al, 2017), question-answering (Choi et al, 2017), and dialogue response generation (Dhingra et al, 2017). In these studies on neural text generation, it has been known that a modelensemble method, which predicts output text by averaging multiple text-generation models at decoding time, is effective even for text-generation tasks, and many state-of-the-art results have been obtained with ensemble models.…”