Relational Grounding Failures in Zero-Shot Cross-Lingual Dialogue Summarization with Small Language Models

Yunwoo Lee, Ziwa Li, Jennifer Huang


Abstract
We diagnose relational grounding failures in zero-shot English-to-Chinese dialogue summarization with small language models (SLMs). We develop and apply a Dialogue-Semantic Grounding Error Taxonomy to evaluate three open-weight SLMs alongside a supervised mBART baseline. The taxonomy captures errors in entities, events, speaker roles, circumstances, modality, discourse outcomes, omissions, and language or format issues. Our analysis shows that SLM hallucinations often involve relation-sensitive distortions of dialogue-relevant content: models may preserve source-relevant participants, events, or circumstances while altering who did what, under what conditions, or with what outcome. These findings position the taxonomy as a diagnostic evaluation framework for dialogue summarization, revealing relation-sensitive faithfulness failures that reference-based metrics may obscure.
Anthology ID:
2026.groundlm-1.31
Volume:
Proceedings of the 1st Workshop on Grounding Language Models: Learning Faithfully and Efficiently (GroundLM 2026)
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Yimu Wang, Yee Man Choi, Di Wu, Siqi Ouyang, Mozhgan Nasr Azadani, Yi R. (May) Fung
Venues:
GroundLM | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
402–411
Language:
URL:
https://aclanthology.org/2026.groundlm-1.31/
DOI:
Bibkey:
Cite (ACL):
Yunwoo Lee, Ziwa Li, and Jennifer Huang. 2026. Relational Grounding Failures in Zero-Shot Cross-Lingual Dialogue Summarization with Small Language Models. In Proceedings of the 1st Workshop on Grounding Language Models: Learning Faithfully and Efficiently (GroundLM 2026), pages 402–411, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Relational Grounding Failures in Zero-Shot Cross-Lingual Dialogue Summarization with Small Language Models (Lee et al., GroundLM 2026)
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PDF:
https://aclanthology.org/2026.groundlm-1.31.pdf