DEPLAIN: A German Parallel Corpus with Intralingual Translations into Plain Language for Sentence and Document Simplification

TL;DR

DEplain is a newly created German parallel corpus with professionally aligned simplifications in plain German, designed to improve automatic sentence and document simplification systems, and includes tools for expanding and aligning additional data.

Contribution

The paper introduces DEplain, a high-quality German parallel corpus for text simplification, along with alignment methods and tools to facilitate corpus expansion and model training.

Findings

Transformer-based models trained on DEplain show promising results.

The corpus includes over 15,000 sentence pairs from news and web domains.

Tools for automatic alignment and web harvesting are developed and shared.

Abstract

Text simplification is an intralingual translation task in which documents, or sentences of a complex source text are simplified for a target audience. The success of automatic text simplification systems is highly dependent on the quality of parallel data used for training and evaluation. To advance sentence simplification and document simplification in German, this paper presents DEplain, a new dataset of parallel, professionally written and manually aligned simplifications in plain German ("plain DE" or in German: "Einfache Sprache"). DEplain consists of a news domain (approx. 500 document pairs, approx. 13k sentence pairs) and a web-domain corpus (approx. 150 aligned documents, approx. 2k aligned sentence pairs). In addition, we are building a web harvester and experimenting with automatic alignment methods to facilitate the integration of non-aligned and to be published parallel documents. Using this approach, we are dynamically increasing the web domain corpus, so it is currently extended to approx. 750 document pairs and approx. 3.5k aligned sentence pairs. We show that using DEplain to train a transformer-based seq2seq text simplification model can achieve promising results. We make available the corpus, the adapted alignment methods for German, the web harvester and the trained models here: https://github.com/rstodden/DEPlain.