UCSC NLP at SemEval-2026 Task 10: Boundary-Aware Span Extraction and RoBERTa Classification for Conspiracy Detection
Dom Marhoefer, Milos Suvakovic, Glenn Grant-Richards, Aidan Pinero, Ryan King
Abstract
We present our systems for SemEval-2026 Task10 (PsyCoMark), addressing conspiracy markerextraction (Subtask 1) and document-level con-spiracy detection (Subtask 2). For marker ex-traction, we formulate the task as multi-labelspan classification over enumerated candidatespans, using IoU≥0.95 positive labeling, hard-negative sampling, and containment-based non-maximum suppression (NMS) with boundary-aware span representations. Document classi-fication is modeled independently using a se-quence classifier with label smoothing and astratified train–validation split. Analysis showsthat entity-like roles (Actor, Victim) are de-tected robustly, while abstract roles (Action,Effect, Evidence) remain sensitive to boundarycriteria. On the official test set, our systemsrank 7th in Subtask 1 (0.2251 macro F1) and12th in Subtask 2 (0.7694 weighted F1).- Anthology ID:
- 2026.semeval-1.194
- 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:
- 1495–1500
- Language:
- URL:
- https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.194/
- DOI:
- Cite (ACL):
- Dom Marhoefer, Milos Suvakovic, Glenn Grant-Richards, Aidan Pinero, and Ryan King. 2026. UCSC NLP at SemEval-2026 Task 10: Boundary-Aware Span Extraction and RoBERTa Classification for Conspiracy Detection. In Proceedings of the 20th International Workshop on Semantic Evaluation (2026), pages 1495–1500, San Diego, California, USA. Association for Computational Linguistics.
- Cite (Informal):
- UCSC NLP at SemEval-2026 Task 10: Boundary-Aware Span Extraction and RoBERTa Classification for Conspiracy Detection (Marhoefer et al., SemEval 2026)
- PDF:
- https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.194.pdf