@inproceedings{liu-etal-2026-locodec,
title = "{L}o{C}o{D}ec: Robust Decoding for {LLM}-based Sequence-Structured Prediction",
author = "Liu, Chang and
Wang, Peiyan and
Feng, Yubo and
Wang, Libang and
Jiang, Feiyan and
Song, Yan",
editor = "Lee, Hung-Yi and
Dev, Sunipa and
Li, Jessy and
Elliott, Desmond",
booktitle = "Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing",
month = oct,
year = "2026",
address = "Budapest, Hungary",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.emnlp-main.1457/",
pages = "33312--33330",
ISBN = "979-8-89176-459-0",
abstract = "Many Natural Language Processing (NLP) tasks, including information extraction, dialogue understanding, and sentiment analysis, can be formulated as structured prediction over sequences or spans. Although Large Language Model (LLM)-based methods have achieved strong performance on standard benchmarks for such tasks, their robustness under natural sentence-level perturbations and their controllability in producing valid structures remain insufficiently studied. In this paper, we propose Locality-aware Constrained Decoding (LoCoDec), a method for LLM-based structured prediction over sequences and spans that formulates decoding as constrained token paraphrasing. LoCoDec combines neighborhood context, which reduces long-text noise, with structural decoding constraints that enforce source-faithful and well-formed outputs. Experiments on sixteen benchmarks of six tasks show that LoCoDec remains competitive in S-F1 and P-F1, while achieving the best R-F1 on all datasets. Ablation results show that removing neighborhood context reduces R-F1 by up to 16.23 points. Overall, LoCoDec improves the robustness and structural consistency of LLM-based structured prediction."
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<abstract>Many Natural Language Processing (NLP) tasks, including information extraction, dialogue understanding, and sentiment analysis, can be formulated as structured prediction over sequences or spans. Although Large Language Model (LLM)-based methods have achieved strong performance on standard benchmarks for such tasks, their robustness under natural sentence-level perturbations and their controllability in producing valid structures remain insufficiently studied. In this paper, we propose Locality-aware Constrained Decoding (LoCoDec), a method for LLM-based structured prediction over sequences and spans that formulates decoding as constrained token paraphrasing. LoCoDec combines neighborhood context, which reduces long-text noise, with structural decoding constraints that enforce source-faithful and well-formed outputs. Experiments on sixteen benchmarks of six tasks show that LoCoDec remains competitive in S-F1 and P-F1, while achieving the best R-F1 on all datasets. Ablation results show that removing neighborhood context reduces R-F1 by up to 16.23 points. Overall, LoCoDec improves the robustness and structural consistency of LLM-based structured prediction.</abstract>
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%0 Conference Proceedings
%T LoCoDec: Robust Decoding for LLM-based Sequence-Structured Prediction
%A Liu, Chang
%A Wang, Peiyan
%A Feng, Yubo
%A Wang, Libang
%A Jiang, Feiyan
%A Song, Yan
%Y Lee, Hung-Yi
%Y Dev, Sunipa
%Y Li, Jessy
%Y Elliott, Desmond
%S Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
%D 2026
%8 October
%I Association for Computational Linguistics
%C Budapest, Hungary
%@ 979-8-89176-459-0
%F liu-etal-2026-locodec
%X Many Natural Language Processing (NLP) tasks, including information extraction, dialogue understanding, and sentiment analysis, can be formulated as structured prediction over sequences or spans. Although Large Language Model (LLM)-based methods have achieved strong performance on standard benchmarks for such tasks, their robustness under natural sentence-level perturbations and their controllability in producing valid structures remain insufficiently studied. In this paper, we propose Locality-aware Constrained Decoding (LoCoDec), a method for LLM-based structured prediction over sequences and spans that formulates decoding as constrained token paraphrasing. LoCoDec combines neighborhood context, which reduces long-text noise, with structural decoding constraints that enforce source-faithful and well-formed outputs. Experiments on sixteen benchmarks of six tasks show that LoCoDec remains competitive in S-F1 and P-F1, while achieving the best R-F1 on all datasets. Ablation results show that removing neighborhood context reduces R-F1 by up to 16.23 points. Overall, LoCoDec improves the robustness and structural consistency of LLM-based structured prediction.
%U https://aclanthology.org/2026.emnlp-main.1457/
%P 33312-33330
Markdown (Informal)
[LoCoDec: Robust Decoding for LLM-based Sequence-Structured Prediction](https://aclanthology.org/2026.emnlp-main.1457/) (Liu et al., EMNLP 2026)
ACL