Large-scale Hierarchical Alignment for Author Style Transfer

We propose a simple method for extracting pseudo-parallel monolingual sentence pairs from comparable corpora representative of two different author styles, such as scientific papers and Wikipedia articles. Our approach is to first hierarchically search for nearest document neighbours and then for sentences therein. We demonstrate the effectiveness of our method through automatic and extrinsic evaluation on two tasks: text simplification from Wikipedia to Simple Wikipedia and style transfer from scientific journal articles to press releases. We show that pseudo-parallel sentences extracted with our method not only improve existing parallel data, but can even lead to competitive performance on their own.