VARH-AI at SemEval-2026 Task 10: Exploiting Architectural Diversity with Transformer-SSM Ensembles and Confidence-Based Iterative Refinement for Conspiracy Detection

Hritav Solanki, Shubham Sharma, Manish Prasad, Rakhi Agrawal, Yashvardhan Sharma


Abstract
This paper describes our system for SemEval 2026 Task 10 (PsyCoMark), focusing on Subtask 2: binary conspiracy classification in Reddit submission statements. We present a heterogeneous ensemble approach that combines Transformer-based models (DeBERTa, RoBERTa) with State-Space Models (Mamba) to leverage architectural diversity for improved generalization. Our key contributions include: (1) Bidirectional Mamba (BiMamba), adapting state-space sequence models for bidirectional document classification; (2) (2) a safety-switched multi-task training setup that uses marker supervision only for gold-annotated samples, preventing noisy pseudo-labeled rows from affecting the span extraction objective; and (3) Confidence-Based Iterative Refinement, using committee voting for high-quality pseudo-label generation. Our best official submission achieved a weighted F1 score of 0.78 on the Subtask 2 test set, ranking 4th on the public CodaBench leaderboard. We provide detailed ablation studies demonstrating the complementary contributions of each architectural component to inform future research directions.
Anthology ID:
2026.semeval-1.138
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:
1000–1005
Language:
URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.138/
DOI:
Bibkey:
Cite (ACL):
Hritav Solanki, Shubham Sharma, Manish Prasad, Rakhi Agrawal, and Yashvardhan Sharma. 2026. VARH-AI at SemEval-2026 Task 10: Exploiting Architectural Diversity with Transformer-SSM Ensembles and Confidence-Based Iterative Refinement for Conspiracy Detection. In Proceedings of the 20th International Workshop on Semantic Evaluation (2026), pages 1000–1005, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
VARH-AI at SemEval-2026 Task 10: Exploiting Architectural Diversity with Transformer-SSM Ensembles and Confidence-Based Iterative Refinement for Conspiracy Detection (Solanki et al., SemEval 2026)
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https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.138.pdf
Supplementarymaterial:
 2026.semeval-1.138.SupplementaryMaterial.zip
Supplementarymaterial:
 2026.semeval-1.138.SupplementaryMaterial.docx