Xudong Han


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Evaluating Debiasing Techniques for Intersectional Biases
Shivashankar Subramanian | Xudong Han | Timothy Baldwin | Trevor Cohn | Lea Frermann
Proceedings of the 2021 Conference on Empirical Methods in Natural Language Processing

Bias is pervasive for NLP models, motivating the development of automatic debiasing techniques. Evaluation of NLP debiasing methods has largely been limited to binary attributes in isolation, e.g., debiasing with respect to binary gender or race, however many corpora involve multiple such attributes, possibly with higher cardinality. In this paper we argue that a truly fair model must consider ‘gerrymandering’ groups which comprise not only single attributes, but also intersectional groups. We evaluate a form of bias-constrained model which is new to NLP, as well an extension of the iterative nullspace projection technique which can handle multiple identities.

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Decoupling Adversarial Training for Fair NLP
Xudong Han | Timothy Baldwin | Trevor Cohn
Findings of the Association for Computational Linguistics: ACL-IJCNLP 2021

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Diverse Adversaries for Mitigating Bias in Training
Xudong Han | Timothy Baldwin | Trevor Cohn
Proceedings of the 16th Conference of the European Chapter of the Association for Computational Linguistics: Main Volume

Adversarial learning can learn fairer and less biased models of language processing than standard training. However, current adversarial techniques only partially mitigate the problem of model bias, added to which their training procedures are often unstable. In this paper, we propose a novel approach to adversarial learning based on the use of multiple diverse discriminators, whereby discriminators are encouraged to learn orthogonal hidden representations from one another. Experimental results show that our method substantially improves over standard adversarial removal methods, in terms of reducing bias and stability of training.


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Grounding learning of modifier dynamics: An application to color naming
Xudong Han | Philip Schulz | Trevor Cohn
Proceedings of the 2019 Conference on Empirical Methods in Natural Language Processing and the 9th International Joint Conference on Natural Language Processing (EMNLP-IJCNLP)

Grounding is crucial for natural language understanding. An important subtask is to understand modified color expressions, such as “light blue”. We present a model of color modifiers that, compared with previous additive models in RGB space, learns more complex transformations. In addition, we present a model that operates in the HSV color space. We show that certain adjectives are better modeled in that space. To account for all modifiers, we train a hard ensemble model that selects a color space depending on the modifier-color pair. Experimental results show significant and consistent improvements compared to the state-of-the-art baseline model.