Yu Fan


2025

pdf bib
The Medium Is Not the Message: Deconfounding Document Embeddings via Linear Concept Erasure
Yu Fan | Yang Tian | Shauli Ravfogel | Mrinmaya Sachan | Elliott Ash | Alexander Miserlis Hoyle
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing

Embedding-based similarity metrics between text sequences can be influenced not just by the content dimensions we most care about, but can also be biased by spurious attributes like the text’s source or language. These document confounders cause problems for many applications, but especially those that need to pool texts from different corpora. This paper shows that a debiasing algorithm that removes information about observed confounders from the encoder representations substantially reduces these biases at a minimal computational cost. Document similarity and clustering metrics improve across every embedding variant and task we evaluate—often dramatically. Interestingly, performance on out-of-distribution benchmarks is not impacted, indicating that the embeddings are not otherwise degraded.

pdf bib
Co-DETECT: Collaborative Discovery of Edge Cases in Text Classification
Chenfei Xiong | Jingwei Ni | Yu Fan | Vilém Zouhar | Donya Rooein | Lorena Calvo-Bartolomé | Alexander Miserlis Hoyle | Zhijing Jin | Mrinmaya Sachan | Markus Leippold | Dirk Hovy | Mennatallah El-Assady | Elliott Ash
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing: System Demonstrations

We introduce Co-DETECT (Collaborative Discovery of Edge cases in TExt ClassificaTion), a novel mixed-initiative annotation framework that integrates human expertise with automatic annotation guided by large language models (LLMs). Co-DETECT starts with an initial, sketch-level codebook and dataset provided by a domain expert, then leverages the LLM to annotate the data and identify edge cases that are not well described by the initial codebook. Specifically, Co-DETECT flags challenging examples, induces high-level, generalizable descriptions of edge cases, and assists user in incorporating edge case handling rules to improve the codebook. This iterative process enables more effective handling of nuanced phenomena through compact, generalizable annotation rules. Extensive user study, qualitative and quantitative analyses prove the effectiveness of Co-DETECT.