Christopher Brückner


2026

Documents related to the Holocaust increasingly move into the focus of Natural Language Processing research, including the digitization of written text, the automatic transcription of oral archives, and interpretive downstream tasks such as Named Entity Recognition. However, most modern language models are trained primarily on modern text, and thus struggle with historical language, historical entities, and domain-specific terminology. Furthermore, transcribed speech introduces challenges such as transcription errors, noise, filler words, and dialectal speech not often contained in textual datasets. We present XLM-RoBERTa-malach, a text encoder domain-adapted to oral testimonies of Holocaust survivors in seven languages. In addition to descriptions of the data acquisition via Automatic Speech Recognition, data augmentation via Machine Translation, and the continued pretraining of a state-of-the-art multilingual transformer, we evaluate the domain-adapted model on the Named Entity Recognition task. Experiments on this task show superior performance over the general-domain transformer in a multilingual domain-specific setting, including languages not seen during the domain adaptation.
We present MalachNER, a new multilingual dataset for Named Entity Recognition (NER) in testimonies of Holocaust survivors. MalachNER has been sourced from different archives and annotated based on comprehensive domain-specific guidelines refined by a collaboration of international experts. Covering 10 European languages, differs significantly from previously released datasets: It is primarily based on noisy, verbatim transcribed speech, rather than on digitized written documents. These transcripts are characterized, among other challenges, by fillers, dialectal speech, and in-line annotations indicating incomprehensible words, which are not commonly encountered in other datasets. However, large volumes of yet unprocessed oral history make such a dataset a necessity. In addition to the description of the dataset and its annotation guidelines, we show with baseline experiments that MalachNER is complementary with previously released data, and the key to training domain-specific language models that generalize well to written and oral testimony alike, achieving state-of-the-art performance on both types of documents.

2025

Classification problems can often be tackled by modeling label hierarchies with broader categories in a graph and solving the task via node classification. While recent advances have shown that hyperbolic space is more suitable than Euclidean space for learning graph representations, this concept has yet to be applied to text classification, where node features first need to be extracted from text embeddings. A prototype of such an architecture is this contribution to the Slavic NLP 2025 shared task on the multi-label classification of persuasion techniques in parliamentary debates and social media posts. We do not achieve state-of-the-art performance, but outline the benefits of this hierarchical node classification approach and the advantages of hyperbolic graph embeddings

2024