Retriv at BLP-2025 Task 1: A Transformer Ensemble and Multi-Task Learning Approach for Bangla Hate Speech Identification

Sourav Saha, K M Nafi Asib, Mohammed Moshiul Hoque


Abstract
This paper addresses the problem of Bangla hate speech identification, a socially impactful yet linguistically challenging task. As part of the Bangla Multi-task Hate Speech Identification shared task at the BLP Workshop, IJCNLP-AACL 2025, we participated in all three subtasks: (1A) hate type classification, (1B) target group identification, and (1C) joint detection of type, severity, and target. For subtasks 1A and 1B, we employed a soft-voting ensemble of transformer models (BanglaBERT, MuRIL, IndicBERTv2). For subtask 1C, we trained three multitask variants and aggregated their predictions through a weighted voting ensemble. Our systems achieved micro-f1 scores of 72.75% (1A) and 72.69% (1B), and a weighted micro-f1 score of 72.62% (1C). On the shared task leaderboard, these corresponded to 9th, 10th, and 7th positions, respectively. These results highlight the promise of transformer ensembles and weighted multitask frameworks for advancing Bangla hate speech detection in low-resource contexts. We made experimental scripts publicly available for the community.
Anthology ID:
2025.banglalp-1.43
Volume:
Proceedings of the Second Workshop on Bangla Language Processing (BLP-2025)
Month:
December
Year:
2025
Address:
Mumbai, India
Editors:
Firoj Alam, Sudipta Kar, Shammur Absar Chowdhury, Naeemul Hassan, Enamul Hoque Prince, Mohiuddin Tasnim, Md Rashad Al Hasan Rony, Md Tahmid Rahman Rahman
Venues:
BanglaLP | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
485–491
Language:
URL:
https://preview.aclanthology.org/ingest-ijcnlp-aacl/2025.banglalp-1.43/
DOI:
Bibkey:
Cite (ACL):
Sourav Saha, K M Nafi Asib, and Mohammed Moshiul Hoque. 2025. Retriv at BLP-2025 Task 1: A Transformer Ensemble and Multi-Task Learning Approach for Bangla Hate Speech Identification. In Proceedings of the Second Workshop on Bangla Language Processing (BLP-2025), pages 485–491, Mumbai, India. Association for Computational Linguistics.
Cite (Informal):
Retriv at BLP-2025 Task 1: A Transformer Ensemble and Multi-Task Learning Approach for Bangla Hate Speech Identification (Saha et al., BanglaLP 2025)
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PDF:
https://preview.aclanthology.org/ingest-ijcnlp-aacl/2025.banglalp-1.43.pdf