CSE-UOI at SemEval-2026 Task 6: A Two-Stage Heterogeneous Ensemble with Deliberative Complexity Gating for Political Evasion Detection

Christos Tzouvaras, Konstantinos Skianis, Athanasios Voulodimos


Abstract
This paper describes our system for SemEval-2026 Task 6, which classifies clarity of responses in political interviews into three categories: Clear Reply, Ambivalent, and Clear Non-Reply. We propose a heterogeneous dual large language model (LLM) ensemble via self-consistency (SC) and weighted voting, and a novel post-hoc correction mechanism, Deliberative Complexity Gating (DCG). This mechanism uses cross-model behavioral signals and exploits the finding that an LLM response-length proxy correlates strongly with sample ambiguity. To further examine mechanisms for improving ambiguity detection, we evaluated multi-agent debate as an alternative strategy for increasing deliberative capacity. Unlike DCG, which adaptively gates reasoning using cross-model behavioral signals, debate increases agent count without increasing model diversity. Our solution achieved a Macro-F1 score of 0.85 on the evaluation set, securing 3rd place and tied with the second-best reportedscore.
Anthology ID:
2026.semeval-1.435
Volume:
Proceedings of the 20th International Workshop on Semantic Evaluation (2026)
Month:
July
Year:
2026
Address:
San Diego, California, USA
Editors:
Ekaterina Kochmar, Debanjan Ghosh, Kai North, Mamoru Komachi
Venues:
SemEval | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
3524–3535
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URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.435/
DOI:
Bibkey:
Cite (ACL):
Christos Tzouvaras, Konstantinos Skianis, and Athanasios Voulodimos. 2026. CSE-UOI at SemEval-2026 Task 6: A Two-Stage Heterogeneous Ensemble with Deliberative Complexity Gating for Political Evasion Detection. In Proceedings of the 20th International Workshop on Semantic Evaluation (2026), pages 3524–3535, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
CSE-UOI at SemEval-2026 Task 6: A Two-Stage Heterogeneous Ensemble with Deliberative Complexity Gating for Political Evasion Detection (Tzouvaras et al., SemEval 2026)
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https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.435.pdf
Supplementarymaterial:
 2026.semeval-1.435.SupplementaryMaterial.zip