On the Properties of Neural Machine Translation: Encoder–Decoder Approaches
Analyzes encoder-decoder neural machine translation models, showing performance drops with longer sentences and more unknown words.
Neural machine translation is a then-new approach to statistical machine translation built purely from neural networks, using an encoder that maps a variable-length sentence to a fixed-length representation and a decoder that generates the translation. The paper analyzes two models: an RNN Encoder-Decoder and a newly proposed gated recursive convolutional neural network. Quality is good for short sentences without unknown words but degrades rapidly as sentence length and unknown words grow; the gated model learns grammatical structure automatically.
Based on: On the Properties of Neural Machine Translation: Encoder–Decoder Approaches · SSST@EMNLP