Huimin Chen


2024

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Controllable Preference Optimization: Toward Controllable Multi-Objective Alignment
Yiju Guo | Ganqu Cui | Lifan Yuan | Ning Ding | Zexu Sun | Bowen Sun | Huimin Chen | Ruobing Xie | Jie Zhou | Yankai Lin | Zhiyuan Liu | Maosong Sun
Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing

Alignment in artificial intelligence pursues the consistency between model responses and human preferences as well as values. In practice, the multifaceted nature of human preferences inadvertently introduces what is known as the ”alignment tax”–a compromise where enhancements in alignment within one objective (e.g., harmlessness) can diminish performance in others (e.g., helpfulness). However, existing alignment techniques are mostly unidirectional, leading to suboptimal trade-offs and poor flexibility over various objectives. To navigate this challenge, we argue the prominence of grounding LLMs with evident preferences. We introduce controllable preference optimization (CPO), which explicitly specifies preference scores for different objectives, thereby guiding the model to generate responses that meet the requirements. Our experimental analysis reveals that the aligned models can provide responses that match various preferences among the ”3H” (helpfulness, honesty, harmlessness) desiderata. Furthermore, by introducing diverse data and alignment goals, we surpass baseline methods in aligning with single objectives, hence mitigating the impact of the alignment tax and achieving improvements in multi-objective alignment.

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Enhancing Legal Case Retrieval via Scaling High-quality Synthetic Query-Candidate Pairs
Cheng Gao | Chaojun Xiao | Zhenghao Liu | Huimin Chen | Zhiyuan Liu | Maosong Sun
Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing

Legal case retrieval (LCR) aims to provide similar cases as references for a given fact description. This task is crucial for promoting consistent judgments in similar cases, effectively enhancing judicial fairness and improving work efficiency for judges. However, existing works face two main challenges for real-world applications: existing works mainly focus on case-to-case retrieval using lengthy queries, which does not match real-world scenarios; and the limited data scale, with current datasets containing only hundreds of queries, is insufficient to satisfy the training requirements of existing data-hungry neural models. To address these issues, we introduce an automated method to construct synthetic query-candidate pairs and build the largest LCR dataset to date, LEAD, which is hundreds of times larger than existing datasets. This data construction method can provide ample training signals for LCR models. Experimental results demonstrate that model training with our constructed data can achieve state-of-the-art results on two widely-used LCR benchmarks. Besides, the construction method can also be applied to civil cases and achieve promising results. The data and codes can be found in https://github.com/thunlp/LEAD.

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TaiChi: Improving the Robustness of NLP Models by Seeking Common Ground While Reserving Differences
Huimin Chen | Chengyu Wang | Yanhao Wang | Cen Chen | Yinggui Wang
Proceedings of the 2024 Joint International Conference on Computational Linguistics, Language Resources and Evaluation (LREC-COLING 2024)

Recent studies have shown that Pre-trained Language Models (PLMs) are vulnerable to adversarial examples, crafted by introducing human-imperceptible perturbations to clean examples to deceive the models. This vulnerability stems from the divergence in the data distributions of clean and adversarial examples. Therefore, addressing this issue involves teaching the model to diminish the differences between the two types of samples and to focus more on their similarities. To this end, we propose a novel approach named TaiChi that employs a Siamese network architecture. Specifically, it consists of two sub-networks sharing the same structure but trained on clean and adversarial samples, respectively, and uses a contrastive learning strategy to encourage the generation of similar language representations for both kinds of samples. Furthermore, it utilizes the Kullback-Leibler (KL) divergence loss to enhance the consistency in the predictive behavior of the two sub-networks. Extensive experiments across three widely used datasets demonstrate that TaiChi achieves superior trade-offs between robustness to adversarial attacks at token and character levels and accuracy on clean examples compared to previous defense methods. Our code and data are publicly available at https://github.com/sai4july/TaiChi.

2019

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Jiuge: A Human-Machine Collaborative Chinese Classical Poetry Generation System
Guo Zhipeng | Xiaoyuan Yi | Maosong Sun | Wenhao Li | Cheng Yang | Jiannan Liang | Huimin Chen | Yuhui Zhang | Ruoyu Li
Proceedings of the 57th Annual Meeting of the Association for Computational Linguistics: System Demonstrations

Research on the automatic generation of poetry, the treasure of human culture, has lasted for decades. Most existing systems, however, are merely model-oriented, which input some user-specified keywords and directly complete the generation process in one pass, with little user participation. We believe that the machine, being a collaborator or an assistant, should not replace human beings in poetic creation. Therefore, we proposed Jiuge, a human-machine collaborative Chinese classical poetry generation system. Unlike previous systems, Jiuge allows users to revise the unsatisfied parts of a generated poem draft repeatedly. According to the revision, the poem will be dynamically updated and regenerated. After the revision and modification procedure, the user can write a satisfying poem together with Jiuge system collaboratively. Besides, Jiuge can accept multi-modal inputs, such as keywords, plain text or images. By exposing the options of poetry genres, styles and revision modes, Jiuge, acting as a professional assistant, allows constant and active participation of users in poetic creation.

2016

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Neural Sentiment Classification with User and Product Attention
Huimin Chen | Maosong Sun | Cunchao Tu | Yankai Lin | Zhiyuan Liu
Proceedings of the 2016 Conference on Empirical Methods in Natural Language Processing