Gated Residual Discrepancy for Efficient Bi-Encoder Factuality Verification

Zeyang Liu, Jingfeng Xue, Jiarun Fu, Wenbiao Du, Xiuqi Yang, Yifeng Fu, Junbao Chen, Yong Wang


Abstract
Large Language Models (LLMs) often generate specious hallucinations, creating an urgent need for post-hoc factuality verification against reliable evidence. Existing verification methods incur substantial computational overhead due to joint evidence–claim encoding. While bi-encoders offer a highly efficient alternative, they struggle with asymmetric entailment and are severely vulnerable to contextual noise. To address these challenges, we propose Gated Residual Discrepancy (GRD), a highly efficient bi-encoder framework for factuality verification. To explicitly capture asymmetric entailment, GRD pioneers a difference-dominant paradigm, extracting dual-view vector differences. To mitigate the vulnerability to contextual noise, GRD employs an adaptive gating mechanism that dynamically filters contextual noise, preventing large semantic backgrounds from masking critical errors, thereby enabling highly sensitive verification over broad evidence contexts. Experiments across various benchmarks show GRD achieves 79.99% average Macro-F1, trailing the strongest cross-encoder baseline by only 1.15 points while delivering a 23.55× speedup with only a fraction of the computational FLOPs.
Anthology ID:
2026.emnlp-main.84
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
1939–1952
Language:
URL:
https://aclanthology.org/2026.emnlp-main.84/
DOI:
Bibkey:
Cite (ACL):
Zeyang Liu, Jingfeng Xue, Jiarun Fu, Wenbiao Du, Xiuqi Yang, Yifeng Fu, Junbao Chen, and Yong Wang. 2026. Gated Residual Discrepancy for Efficient Bi-Encoder Factuality Verification. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 1939–1952, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Gated Residual Discrepancy for Efficient Bi-Encoder Factuality Verification (Liu et al., EMNLP 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.emnlp-main.84.pdf