Sebastian Gombert
2026
Report on the BEA 2026 Shared Task on Rubric-based Short Answer Scoring for German
Sebastian Gombert | Zhifan Sun | Fabian Zehner | Jannik Lossjew | Tobias Wyrwich | Berrit Czinczel | David Bednorz | Sascha Bernholt | Knut Neumann | Ute Harms | Aiso Heinze | Hendrik Drachsler
Proceedings of the 21st Workshop on Innovative Use of NLP for Building Educational Applications (BEA 2026)
Sebastian Gombert | Zhifan Sun | Fabian Zehner | Jannik Lossjew | Tobias Wyrwich | Berrit Czinczel | David Bednorz | Sascha Bernholt | Knut Neumann | Ute Harms | Aiso Heinze | Hendrik Drachsler
Proceedings of the 21st Workshop on Innovative Use of NLP for Building Educational Applications (BEA 2026)
We present the BEA 2026 shared task on rubric-based short answer scoring for German. Rubric-based short answer scoring is a case of automatic short answer scoring (ASAS) that requires models to apply textual scoring rubrics to student answers as a basis for assigning scores. For the shared task, we introduced a novel German-language dataset from multiple STEM domains to provide a comprehensive benchmark for this problem. The dataset was designed to evaluate both performance and generalization (the latter, by distinguishing between seen and unseen questions), as well as coarse- and fine-grained scoring (2-way vs. 3-way). The systems submitted to the shared task cover a wide range of approaches, including fine-tuned large language models, prompt-based methods, human-AI collaboration strategies, or a combination of these. The results show that structured, task-adapted LLM systems achieved the strongest performance across all tracks. The winning system, IWM-DKM, combined LoRA fine-tuning of Qwen models with rubric-aware input structuring, including checklist-style reasoning, rubric reframing as decision trees, background knowledge injection, and ensemble voting. Other systems similarly relied on fine-tuned LLMs, retrieval-augmented prompting, encoder–LLM ensembles, or weighted aggregation strategies. Overall, the shared task results show that rubric-based scoring benefits most from systems that explicitly operationalise rubric semantics, while generalisation to unseen questions remains a central challenge.
Rubrics as Semantic Subspaces: A Unified Approach to Rubric-based Constructed Response Scoring across Short Answers and Essays
Sebastian Gombert | Sonja Hahn | Nico Andersen | Leon Camus | Zhifan Sun | Ngoc Nhu Hao Nguyen | Fabian Zehner | Longwei Cong | Alexander Mehler | Hendrik Drachsler
Proceedings of the 21st Workshop on Innovative Use of NLP for Building Educational Applications (BEA 2026)
Sebastian Gombert | Sonja Hahn | Nico Andersen | Leon Camus | Zhifan Sun | Ngoc Nhu Hao Nguyen | Fabian Zehner | Longwei Cong | Alexander Mehler | Hendrik Drachsler
Proceedings of the 21st Workshop on Innovative Use of NLP for Building Educational Applications (BEA 2026)
Rubrics are the primary reference for manual scoring of constructed responses, and there is growing interest in their use in automated scoring methodologies. In this work, we propose Aspect-Grounded Rubric–Answer Alignment (AGRAA), a rubric-based end-to-end scoring framework that models rubric descriptors as latent aspect spaces. Concretely, rubric descriptors are represented as low-dimensional subspaces derived from contextualised transformer embeddings, and student responses are scored according to how strongly their representations align with these rubric-induced spaces relative to the residual space outside them. This formulation provides a geometrically grounded interpretation of rubric-based scoring while enabling end-to-end training with standard transformer encoders. We introduce three distinct architectural variants and evaluate them on multiple short-answer and essay scoring datasets. Across these tasks, AGRAA achieves predictive performance highly competitive with strong neural and feature-based baselines. In addition, the framework yields interpretable intermediate representations that expose which rubric-defined aspects contribute to scoring decisions, enabling decision-aligned explanations grounded in rubric descriptors.
Estimating LLM Grading Ability and Response Difficulty in Automatic Short Answer Grading via Item Response Theory
Longwei Cong | Sonja Hahn | Sebastian Gombert | Leon Camus | Hendrik Drachsler | Ulf Kroehne
Proceedings of the 21st Workshop on Innovative Use of NLP for Building Educational Applications (BEA 2026)
Longwei Cong | Sonja Hahn | Sebastian Gombert | Leon Camus | Hendrik Drachsler | Ulf Kroehne
Proceedings of the 21st Workshop on Innovative Use of NLP for Building Educational Applications (BEA 2026)
Automated short answer grading (ASAG) with large language models (LLMs) is commonly evaluated with aggregate metrics such as macro-F1 and Cohen’s kappa. However, these metrics provide limited insight into how grading performance varies across student responses of differing grading difficulty. We introduce an evaluation framework for LLM-based ASAG based on item response theory (IRT), which models grading correctness as a function of latent grader ability and response grading difficulty. This formulation enables response-level analysis of where LLM graders succeed or fail and reveals robustness differences that are not visible from aggregate scores alone. We apply the framework to 17 open-weight LLMs on the SciEntsBank and Beetle benchmarks. The results show that even models with similar overall performance differ substantially in how sharply their grading accuracy declines as response difficulty increases. In addition, confusion patterns show that errors on difficult responses concentrate disproportionately on the partially_correct_incomplete label, indicating a tendency toward intermediate-label collapse under ambiguity. To characterize difficult responses, we further analyze semantic and linguistic correlates of estimated difficulty. Across both datasets, higher difficulty is associated with weaker semantic alignment to the reference answer, stronger contradiction signals, and greater semantic isolation in embedding space. Overall, these results show that item response theory offers a useful framework for evaluating LLM-based ASAG beyond aggregate performance measures.
2025
GRIPF at TSAR 2025 Shared Task Towards controlled CEFR level simplification with the help of inter-model interactions
David Alfter | Sebastian Gombert
Proceedings of the Fourth Workshop on Text Simplification, Accessibility and Readability (TSAR 2025)
David Alfter | Sebastian Gombert
Proceedings of the Fourth Workshop on Text Simplification, Accessibility and Readability (TSAR 2025)
In this contribution to the CEFR level simplification TSAR 2025 Shared Task, we propose two systems, EZ-SCALAR and SAGA, that implement two differing approaches to prompting LLMs for proficiency-adapted simplification. Our results place us in the middle of the participating teams, and reveal that using external lexical resources to guide simplification improves overall results.
TBA at BEA 2025 Shared Task: Transfer-Learning from DARE-TIES Merged Models for the Pedagogical Ability Assessment of LLM-Powered Math Tutors
Sebastian Gombert | Fabian Zehner | Hendrik Drachsler
Proceedings of the 20th Workshop on Innovative Use of NLP for Building Educational Applications (BEA 2025)
Sebastian Gombert | Fabian Zehner | Hendrik Drachsler
Proceedings of the 20th Workshop on Innovative Use of NLP for Building Educational Applications (BEA 2025)
This paper presents our contribution to the BEA 2025 Shared Task on Pedagogical Ability Assessment of AI-Powered Tutors. The objective of this shared task was to assess the quality of conversational feedback provided by LLM-based math tutors to students regarding four facets: whether the tutors 1) identified mistakes, 2) identified the mistake’s location, 3) provided guidance, and whether they 4) provided actionable feedback. To leverage information across all four labels, we approached the problem with FLAN-T5 models, which we fit for this task using a multi-step pipeline involving regular fine-tuning as well as model merging using the DARE-TIES algorithm. We can demonstrate that our pipeline is beneficial to overall model performance compared to regular fine-tuning. With results on the test set ranging from 52.1 to 68.6 in F1 scores and 62.2% to 87.4% in accuracy, our best models placed 11th of 44 teams in Track 1, 8th of 31 teams in Track 2, 11th of 35 teams in Track 3, and 9th of 30 teams in Track 4. Notably, the classifiers’ recall was relatively poor for underrepresented classes, indicating even greater potential for the employed methodology.
Down the Cascades of Omethi: Hierarchical Automatic Scoring in Large-Scale Assessments
Fabian Zehner | Hyo Jeong Shin | Emily Kerzabi | Andrea Horbach | Sebastian Gombert | Frank Goldhammer | Torsten Zesch | Nico Andersen
Proceedings of the 20th Workshop on Innovative Use of NLP for Building Educational Applications (BEA 2025)
Fabian Zehner | Hyo Jeong Shin | Emily Kerzabi | Andrea Horbach | Sebastian Gombert | Frank Goldhammer | Torsten Zesch | Nico Andersen
Proceedings of the 20th Workshop on Innovative Use of NLP for Building Educational Applications (BEA 2025)
We present the framework Omethi, which is aimed at scoring short text responses in a semi-automatic fashion, particularly fit to international large-scale assessments. We evaluate its effectiveness for the massively multilingual PISA tests. Responses are passed through a conditional flow of hierarchically combined scoring components to assign a score. Once a score is assigned, hierarchically lower components are discarded. Models implemented in this study ranged from lexical matching of normalized texts—with excellent accuracy but weak generalizability—to fine-tuned large language models—with lower accuracy but high generalizability. If not scored by any automatic component, responses are passed on to manual scoring. The paper is the first to provide an evaluation of automatic scoring on multilingual PISA data in eleven languages (including Arabic, Finnish, Hebrew, and Kazakh) from three domains (n = 3.8 million responses). On average, results show a manual effort reduction of 71 percent alongside an agreement of 𝜅 = .957, when including manual scoring, and 𝜅 = .804 for only the automatically scored responses. The evaluation underscores the framework’s effective adaptivity and operational feasibility with its shares of used components varying substantially across domains and languages while maintaining homogeneously high accuracy.
2024
Predicting Item Difficulty and Item Response Time with Scalar-mixed Transformer Encoder Models and Rational Network Regression Heads
Sebastian Gombert | Lukas Menzel | Daniele Di Mitri | Hendrik Drachsler
Proceedings of the 19th Workshop on Innovative Use of NLP for Building Educational Applications (BEA 2024)
Sebastian Gombert | Lukas Menzel | Daniele Di Mitri | Hendrik Drachsler
Proceedings of the 19th Workshop on Innovative Use of NLP for Building Educational Applications (BEA 2024)
This paper describes a contribution to the BEA 2024 Shared Task on Automated Prediction of Item Difficulty and Response Time. The participants in this shared task are to develop models for predicting the difficulty and response time of multiple-choice items in the medical field. These items were taken from the United States Medical Licensing Examination® (USMLE®), a high-stakes medical exam. For this purpose, we evaluated multiple BERT-like pre-trained transformer encoder models, which we combined with Scalar Mixing and two custom 2-layer classification heads using learnable Rational Activations as an activation function, each for predicting one of the two variables of interest in a multi-task setup. Our best models placed first out of 43 for predicting item difficulty and fifth out of 34 for predicting Item Response Time.
2021
TUDA-CCL at SemEval-2021 Task 1: Using Gradient-boosted Regression Tree Ensembles Trained on a Heterogeneous Feature Set for Predicting Lexical Complexity
Sebastian Gombert | Sabine Bartsch
Proceedings of the 15th International Workshop on Semantic Evaluation (SemEval-2021)
Sebastian Gombert | Sabine Bartsch
Proceedings of the 15th International Workshop on Semantic Evaluation (SemEval-2021)
In this paper, we present our systems submitted to SemEval-2021 Task 1 on lexical complexity prediction. The aim of this shared task was to create systems able to predict the lexical complexity of word tokens and bigram multiword expressions within a given sentence context, a continuous value indicating the difficulty in understanding a respective utterance. Our approach relies on gradient boosted regression tree ensembles fitted using a heterogeneous feature set combining linguistic features, static and contextualized word embeddings, psycholinguistic norm lexica, WordNet, word- and character bigram frequencies and inclusion in wordlists to create a model able to assign a word or multiword expression a context-dependent complexity score. We can show that especially contextualised string embeddings can help with predicting lexical complexity.
2020
MultiVitaminBooster at PARSEME Shared Task 2020: Combining Window- and Dependency-Based Features with Multilingual Contextualised Word Embeddings for VMWE Detection
Sebastian Gombert | Sabine Bartsch
Proceedings of the Joint Workshop on Multiword Expressions and Electronic Lexicons
Sebastian Gombert | Sabine Bartsch
Proceedings of the Joint Workshop on Multiword Expressions and Electronic Lexicons
In this paper, we present MultiVitaminBooster, a system implemented for the PARSEME shared task on semi-supervised identification of verbal multiword expressions - edition 1.2. For our approach, we interpret detecting verbal multiword expressions as a token classification task aiming to decide whether a token is part of a verbal multiword expression or not. For this purpose, we train gradient boosting-based models. We encode tokens as feature vectors combining multilingual contextualized word embeddings provided by the XLM-RoBERTa language model with a more traditional linguistic feature set relying on context windows and dependency relations. Our system was ranked 7th in the official open track ranking of the shared task evaluations with an encoding-related bug distorting the results. For this reason we carry out further unofficial evaluations. Unofficial versions of our systems would have achieved higher ranks.
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- Hendrik Drachsler 5
- Fabian Zehner 4
- Nico Andersen 2
- Sabine Bartsch 2
- Leon Camus 2
- Longwei Cong 2
- Sonja Hahn 2
- Zhifan Sun 2
- David Alfter 1
- David Bednorz 1
- Sascha Bernholt 1
- Berrit Czinczel 1
- Daniele Di Mitri 1
- Frank Goldhammer 1
- Ute Harms 1
- Aiso Heinze 1
- Andrea Horbach 1
- Emily Kerzabi 1
- Ulf Kroehne 1
- Jannik Lossjew 1
- Alexander Mehler 1
- Lukas Menzel 1
- Knut Neumann 1
- Ngoc Nhu Hao Nguyen 1
- Hyo Jeong Shin 1
- Tobias Wyrwich 1
- Torsten Zesch 1