LLM-INSTRUCT at UZH Shared Task 2026: Constraint-Aware Retrieval and Selective Debate for Paragraph-Level Argument Mining

Phuong Huu Vu Tran, Long Minh Vo, Son Nguyen Minh Le, Hoang Van


Abstract
We present LLM-INSTRUCT, the winning system for the UZH Shared Task at ArgMining 2026 on paragraph-level argument mining in UN and UNESCO resolutions. The task requires paragraph-type classification, prediction of a subset of 141 official tags, and directed relation prediction under a strict JSON schema setting using only open-weight models up to 8B parameters. We frame the task as constrained structured prediction. The system first narrows the candidate tag space with metadata-aware dense retrieval, then applies constrained decoding with per-dimension caps, and escalates only uncertain cases to a three-agent debate branch.
Anthology ID:
2026.argmining-1.11
Volume:
Proceedings of the 13th Workshop on Argument Mining and Reasoning
Month:
July
Year:
2026
Address:
San Diego, California, USA
Editors:
Mohamed Elaraby, Annette Hautli-Janisz, Julia Romberg, Elena Musi, Federico Ruggeri, John Lawrence
Venues:
ArgMining | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
99–104
Language:
URL:
https://aclanthology.org/2026.argmining-1.11/
DOI:
Bibkey:
Cite (ACL):
Phuong Huu Vu Tran, Long Minh Vo, Son Nguyen Minh Le, and Hoang Van. 2026. LLM-INSTRUCT at UZH Shared Task 2026: Constraint-Aware Retrieval and Selective Debate for Paragraph-Level Argument Mining. In Proceedings of the 13th Workshop on Argument Mining and Reasoning, pages 99–104, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
LLM-INSTRUCT at UZH Shared Task 2026: Constraint-Aware Retrieval and Selective Debate for Paragraph-Level Argument Mining (Tran et al., ArgMining 2026)
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PDF:
https://aclanthology.org/2026.argmining-1.11.pdf