LLM-based Translation Across 500 Years. The Case for Early New High German

The recently developed large language models (LLMs) show surprising translation capabilities for modern languages. In contrast, this paper investigates the ability of GPT-4 and Gemini to translate 500-year-old letters from Early New High German into modern German. We experiment with a corpus from the 16th century that is partly in Latin and partly in ENH-German. This corpus consists of more than 3000 letters that have been edited and annotated by experts from the Institute of Swiss Reformation Studies. We exploit their annotations for the evaluation of machine translation from ENH-German to German. Our experiments show that using the lexical footnotes by the editors in the prompts or directly injected into the text leads to high quality translations.