bm25
FDE interview questions tagged bm25, across every topic.
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Concepts behind "bm25"
The curriculum that explains the ideas these questions test.
Foundational
TF-IDF and BM25BM25 is the lexical scoring function that still beats a lot of fancier setups out of the box. It scores a document by how often the query's terms appear (term frequency), discounted by how common those terms are across the corpus (inverse document frequency), with two refinements: frequency saturation so a term repeated 50 times does not score 50x, and length normalization so long documents do not win by sheer size. It is the backbone of the lexical half of hybrid search.🤖 Retrieval & Agents
Core
Hybrid Search (Lexical + Vector)Hybrid search runs a keyword retriever (BM25) and a dense vector retriever side by side, then merges their result lists, because each one misses cases the other catches. Vectors lose exact codes and rare jargon, BM25 loses paraphrase, and combining them with Reciprocal Rank Fusion usually beats either alone.🤖 Retrieval & AgentsSign in