Mendel292 at SemEval-2026 Task 4: Disentangled Narrative Embeddings for Story Similarity

Mauricio Gruppi, Sankalpa Rijal, Justin Debenedetto


Abstract
This paper describes Mendel292, our system for SemEval-2026 Task 4 on Narrative Story Similarity. We introduce a narrative encoder that decomposes story representations into explicit subspaces for abstract theme, course of action, and outcome, built on a pre-trained sentence embedding model and trainable BiLSTM projection layer with a triplet margin loss objective. We augment the training set via backtranslation, and incorporate weakly supervised multi-task objectives derived from unsupervised narrative clustering.The proposed architecture was designed to learn a latent representation of narratives in a few-shot setting due to a limited amount of traninig data.Despite using a rich pre-trained transformer, the model was outperformed by a unsupervised pooling approach on the classification task.While our systems do not match the top leaderboard scores, they allow us to systematically study the effects of subspace factorization, weak labels, and data augmentation on narrative similarity modeling.
Anthology ID:
2026.semeval-1.324
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:
2575–2582
Language:
URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.324/
DOI:
Bibkey:
Cite (ACL):
Mauricio Gruppi, Sankalpa Rijal, and Justin Debenedetto. 2026. Mendel292 at SemEval-2026 Task 4: Disentangled Narrative Embeddings for Story Similarity. In Proceedings of the 20th International Workshop on Semantic Evaluation (2026), pages 2575–2582, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
Mendel292 at SemEval-2026 Task 4: Disentangled Narrative Embeddings for Story Similarity (Gruppi et al., SemEval 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.324.pdf
Supplementarymaterial:
 2026.semeval-1.324.SupplementaryMaterial.zip