Information Retrieval

Opening — Why this matters now Search systems have grown fluent, but not necessarily intelligent. As enterprises drown in text—contracts, filings, emails, reports—the gap between what users mean and what systems match has become painfully visible. Keyword search still dominates operational systems, while embedding-based similarity often settles for crude averages. This paper challenges that quiet compromise. ...

Retrieval‑augmented generation tends to pick a side: either lean on labeled exemplars (ICL/L‑RAG) that encode task semantics, or on unlabeled corpora (U‑RAG) that provide broad knowledge. HF‑RAG argues we shouldn’t choose. Instead, it proposes a hierarchical fusion: (1) fuse multiple rankers within each source, then (2) fuse across sources by putting scores on a common scale. The result is a simple, training‑free recipe that improves fact verification and, crucially, generalizes better out‑of‑domain. ...