Narrative Team at SemEval-2026 Task 4: Two-Stage Contrastive Learning for Narrative Similarity Assessment

Tatiana Khaidukova, Ana Ciobanu, Daniela Gifu, Diana Trandabat


Abstract
For SemEval-2026 Task 4, we introduce a unified two-stage framework based on a RoBERTa-large encoder. Stage 1 performs contrastive pre-training on synthetic triplets to learn general narrative similarity patterns. Stage 2 fine-tunes the model with a ranking-based objective tailored to Track A.The resulting encoder supports both binary similarity classification (Track A) and narrative embedding generation (Track B) without architectural changes. Our system achieves an accuracy of 0.64 on Track A and 0.69 on Track B, outperforming single-stage baselines and demonstrating that combining synthetic contrastive supervision with task-specific ranking yields stable and reusable narrative representations.
Anthology ID:
2026.semeval-1.22
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:
146–152
Language:
URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.22/
DOI:
Bibkey:
Cite (ACL):
Tatiana Khaidukova, Ana Ciobanu, Daniela Gifu, and Diana Trandabat. 2026. Narrative Team at SemEval-2026 Task 4: Two-Stage Contrastive Learning for Narrative Similarity Assessment. In Proceedings of the 20th International Workshop on Semantic Evaluation (2026), pages 146–152, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
Narrative Team at SemEval-2026 Task 4: Two-Stage Contrastive Learning for Narrative Similarity Assessment (Khaidukova et al., SemEval 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.22.pdf
Supplementarymaterial:
 2026.semeval-1.22.SupplementaryMaterial.zip