CultRAG at SemEval-2026 Task 7: Hybrid Sparse-Dense Retrieval with Entity-Centric Knowledge Bases for Cultural MCQ Answering

Aditya Singh, Rickarya Das


Abstract
We developed CultRAG, a trust-weighted Retrieval-Augmented Generation system for BLEnD Track 2 (SemEval-2026 Task 7), targeting culturally grounded multiple-choice QA across 30 countries. Built on Llama-3.1-8B-Instruct, the six-phase pipeline integrates entity extraction via spaCy, hybrid BM25+FAISS retrieval with Reciprocal Rank Fusion, country-aware filtering, keyword-based intent detection, tiered prompt routing, anti-leak quality filtering to suppress answer-anchoring artifacts, and trust-weighted document reranking with source-credibility tiers. Ablation analysis across eight cumulative configurations and per-country decomposition identify which components contribute and where retrieval helps versus hurts, informing future directions for confidence-conditioned selective retrieval.
Anthology ID:
2026.semeval-1.393
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:
3137–3142
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URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.393/
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Bibkey:
Cite (ACL):
Aditya Singh and Rickarya Das. 2026. CultRAG at SemEval-2026 Task 7: Hybrid Sparse-Dense Retrieval with Entity-Centric Knowledge Bases for Cultural MCQ Answering. In Proceedings of the 20th International Workshop on Semantic Evaluation (2026), pages 3137–3142, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
CultRAG at SemEval-2026 Task 7: Hybrid Sparse-Dense Retrieval with Entity-Centric Knowledge Bases for Cultural MCQ Answering (Singh & Das, SemEval 2026)
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https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.393.pdf
Supplementarymaterial:
 2026.semeval-1.393.SupplementaryMaterial.zip