CuriosAI at SemEval-2026 Task 10:Hybrid approaches to conspiracy span extraction and conspiracy detection

Hiroki Takushima, Fumika Beppu, Aiswariya Manoj Kumar, Yuki Shibata, Takayuki Hori, Daichi Yamaga


Abstract
We present CuriosAI’s system for SemEval-2026 Task 10, addressing Conspiracy Marker Extraction and Conspiracy Detection. For marker extraction, we employ multi-label token classification with a bidirectional transformer (DeBERTa-v3-large) to predict overlapping spans. Alternative feature-based and LLM-based approaches do not surpass the encoder baseline. For Conspiracy Detection, we compare heterogeneous models, including transformer fine-tuning, lexical classifiers, embedding-based models, and LLM-based refinement. Development-optimal models do not always generalize best; logit-level ensembling achieves the strongest test performance (F1=0.7620). These results highlight the importance of bidirectional token modeling for span extraction and calibration-aware ensembling for robust detection.
Anthology ID:
2026.semeval-1.71
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:
497–502
Language:
URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.71/
DOI:
Bibkey:
Cite (ACL):
Hiroki Takushima, Fumika Beppu, Aiswariya Manoj Kumar, Yuki Shibata, Takayuki Hori, and Daichi Yamaga. 2026. CuriosAI at SemEval-2026 Task 10:Hybrid approaches to conspiracy span extraction and conspiracy detection. In Proceedings of the 20th International Workshop on Semantic Evaluation (2026), pages 497–502, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
CuriosAI at SemEval-2026 Task 10:Hybrid approaches to conspiracy span extraction and conspiracy detection (Takushima et al., SemEval 2026)
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https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.71.pdf
Supplementarymaterial:
 2026.semeval-1.71.SupplementaryMaterial.zip