Christian Heumann


2024

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Collaborative Development of Modular Open Source Educational Resources for Natural Language Processing
Matthias Aßenmacher | Andreas Stephan | Leonie Weissweiler | Erion Çano | Ingo Ziegler | Marwin Härttrich | Bernd Bischl | Benjamin Roth | Christian Heumann | Hinrich Schütze
Proceedings of the Sixth Workshop on Teaching NLP

In this work, we present a collaboratively and continuously developed open-source educational resource (OSER) for teaching natural language processing at two different universities. We shed light on the principles we followed for the initial design of the course and the rationale for ongoing developments, followed by a reflection on the inter-university collaboration for designing and maintaining teaching material. When reflecting on the latter, we explicitly emphasize the considerations that need to be made when facing heterogeneous groups and when having to accommodate multiple examination regulations within one single course framework. Relying on the fundamental principles of OSER developments as defined by Bothmann et al. (2023) proved to be an important guideline during this process. The final part pertains to open-sourcing our teaching material, coping with the increasing speed of developments in the field, and integrating the course digitally, also addressing conflicting priorities and challenges we are currently facing.

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Detecting Gender Discrimination on Actor Level Using Linguistic Discourse Analysis
Stefanie Urchs | Veronika Thurner | Matthias Aßenmacher | Christian Heumann | Stephanie Thiemichen
Proceedings of the 5th Workshop on Gender Bias in Natural Language Processing (GeBNLP)

With the usage of tremendous amounts of text data for training powerful large language models such as ChatGPT, the issue of analysing and securing data quality has become more pressing than ever. Any biases, stereotypes and discriminatory patterns that exist in the training data can be reproduced, reinforced or broadly disseminated by the models in production. Therefore, it is crucial to carefully select and monitor the text data that is used as input to train the model. Due to the vast amount of training data, this process needs to be (at least partially) automated. In this work, we introduce a novel approach for automatically detecting gender discrimination in text data on the actor level based on linguistic discourse analysis. Specifically, we combine existing information extraction (IE) techniques to partly automate the qualitative research done in linguistic discourse analysis. We focus on two important steps: Identifying the respectiveperson-named-entity (an actor) and all forms it is referred to (Nomination), and detecting the characteristics it is ascribed (Predication). Asa proof of concept, we integrate these two steps into a pipeline for automated text analysis. The separate building blocks of the pipeline could be flexibly adapted, extended, and scaled for bigger datasets to accommodate a wide range of usage scenarios and specific ML tasks or help social scientists with analysis tasks. We showcase and evaluate our approach on several real and simulated exemplary texts.

2023

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A tailored Handwritten-Text-Recognition System for Medieval Latin
Philipp Koch | Gilary Vera Nuñez | Esteban Garces Arias | Christian Heumann | Matthias Schöffel | Alexander Häberlin | Matthias Assenmacher
Proceedings of the Ancient Language Processing Workshop

The Bavarian Academy of Sciences and Humanities aims to digitize the Medieval Latin Dictionary. This dictionary entails record cards referring to lemmas in medieval Latin, a low-resource language. A crucial step of the digitization process is the handwritten text recognition (HTR) of the handwritten lemmas on the record cards. In our work, we introduce an end-to-end pipeline, tailored for the medieval Latin dictionary, for locating, extracting, and transcribing the lemmas. We employ two state-of-the-art image segmentation models to prepare the initial data set for the HTR task. Further, we experiment with different transformer-based models and conduct a set of experiments to explore the capabilities of different combinations of vision encoders with a GPT-2 decoder. Additionally, we also apply extensive data augmentation resulting in a highly competitive model. The best-performing setup achieved a character error rate of 0.015, which is even superior to the commercial Google Cloud Vision model, and shows more stable performance.

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Automatic Transcription of Handwritten Old Occitan Language
Esteban Garces Arias | Vallari Pai | Matthias Schöffel | Christian Heumann | Matthias Aßenmacher
Proceedings of the 2023 Conference on Empirical Methods in Natural Language Processing

While existing neural network-based approaches have shown promising results in Handwritten Text Recognition (HTR) for high-resource languages and standardized/machine-written text, their application to low-resource languages often presents challenges, resulting in reduced effectiveness. In this paper, we propose an innovative HTR approach that leverages the Transformer architecture for recognizing handwritten Old Occitan language. Given the limited availability of data, which comprises only word pairs of graphical variants and lemmas, we develop and rely on elaborate data augmentation techniques for both text and image data. Our model combines a custom-trained Swin image encoder with a BERT text decoder, which we pre-train using a large-scale augmented synthetic data set and fine-tune on the small human-labeled data set. Experimental results reveal that our approach surpasses the performance of current state-of-the-art models for Old Occitan HTR, including open-source Transformer-based models such as a fine-tuned TrOCR and commercial applications like Google Cloud Vision. To nurture further research and development, we make our models, data sets, and code publicly available.

2022

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Pre-trained language models evaluating themselves - A comparative study
Philipp Koch | Matthias Aßenmacher | Christian Heumann
Proceedings of the Third Workshop on Insights from Negative Results in NLP

Evaluating generated text received new attention with the introduction of model-based metrics in recent years. These new metrics have a higher correlation with human judgments and seemingly overcome many issues of previous n-gram based metrics from the symbolic age. In this work, we examine the recently introduced metrics BERTScore, BLEURT, NUBIA, MoverScore, and Mark-Evaluate (Petersen). We investigate their sensitivity to different types of semantic deterioration (part of speech drop and negation), word order perturbations, word drop, and the common problem of repetition. No metric showed appropriate behaviour for negation, and further none of them was overall sensitive to the other issues mentioned above.

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CC-Top: Constrained Clustering for Dynamic Topic Discovery
Jann Goschenhofer | Pranav Ragupathy | Christian Heumann | Bernd Bischl | Matthias Aßenmacher
Proceedings of the First Workshop on Ever Evolving NLP (EvoNLP)

Research on multi-class text classification of short texts mainly focuses on supervised (transfer) learning approaches, requiring a finite set of pre-defined classes which is constant over time. This work explores deep constrained clustering (CC) as an alternative to supervised learning approaches in a setting with a dynamically changing number of classes, a task we introduce as dynamic topic discovery (DTD).We do so by using pairwise similarity constraints instead of instance-level class labels which allow for a flexible number of classes while exhibiting a competitive performance compared to supervised approaches. First, we substantiate this through a series of experiments and show that CC algorithms exhibit a predictive performance similar to state-of-the-art supervised learning algorithms while requiring less annotation effort. Second, we demonstrate the overclustering capabilities of deep CC for detecting topics in short text data sets in the absence of the ground truth class cardinality during model training. Third, we showcase that these capabilities can be leveraged for the DTD setting as a step towards dynamic learning over time and finally, we release our codebase to nurture further research in this area.

2021

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Benchmarking down-scaled (not so large) pre-trained language models
Matthias Aßenmacher | Patrick Schulze | Christian Heumann
Proceedings of the 17th Conference on Natural Language Processing (KONVENS 2021)

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How to Estimate Continuous Sentiments From Texts Using Binary Training Data
Sandra Wankmüller | Christian Heumann
Proceedings of the 17th Conference on Natural Language Processing (KONVENS 2021)