Hiep K. V. Nguyen
Author directory2026
Copy Less, Ground More: Selective and Confidence-Aware Decoding for Grounded Legal Generation
Tan-Minh Nguyen | Truong Dinh Do | Hiep K. V. Nguyen | Le-Minh Nguyen
Findings of the Association for Computational Linguistics: IJCNLP-AACL 2026
Tan-Minh Nguyen | Truong Dinh Do | Hiep K. V. Nguyen | Le-Minh Nguyen
Findings of the Association for Computational Linguistics: IJCNLP-AACL 2026
While retrieval-augmented generation (RAG) grounds large language models (LLMs) in external knowledge, ensuring faithful evidence utilization in complex domains like law remains challenging. LLMs often ignore retrieved facts or indiscriminately copy from noisy contexts. Existing context-aware decoding methods attempt to mitigate this by amplifying the influence of retrieved content, but they treat the context as a monolithic block—amplifying irrelevant spans alongside evidence—and intervene at every decoding step, incurring substantial inference overhead. To address this, we propose SaCoD (Selective and Confidence-aware Decoding), a training-free inference framework. SaCoD leverages the LLM’s internal attention signals to dynamically isolate salient evidence paragraphs at each step, restricting a customized copy mechanism strictly to relevant facts. Furthermore, an entropy-based gate activates this intervention only when the model is uncertain, bypassing copy operations for deterministic tokens to preserve linguistic fluency and cut computational overhead. Experiments on four legal question-answering benchmarks across three open-weight LLMs demonstrate that SaCoD significantly improves faithfulness and response correctness while substantially reducing inference latency compared with prior context-aware methods.
SPECI: Fine-grained Evaluation of Specificity for Image Captioning
Son T. Luu | Hiep K. V. Nguyen | Trung Bui | Viet Dac Lai | Le-Minh Nguyen
Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
Son T. Luu | Hiep K. V. Nguyen | Trung Bui | Viet Dac Lai | Le-Minh Nguyen
Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
Image Captioning lies at the center of synthetic data generation in computer vision. The quality of the caption defines the behavior of the resulting model trained on image-caption pairs generated by Image Captioning. Measuring the specificity of image captioning plays an important role in supplying high-quality captions for the downstream tasks. To address the challenge of automatically assessing the quality of the caption, we propose SPECI, an automatic metric that decomposes dense captions into atomic facts and evaluates specificity across visual criteria such as granularity, spatial detail, color, and linguistic focus using WordNet-based hyponym levels. Empirical results on the benchmark datasets demonstrate significant correlation with human judgments, and its application in image captioning and image reconstruction tasks highlights the practical utility of SPECI. The source code of SPECI is available at https://github.com/sonlam1102/SPECI.