BM25 excels at exact keyword matches but misses semantic meaning. Dense embedding search understands semantics but fails on rare terms and proper nouns. Hybrid search combines both via Reciprocal Rank Fusion (RRF), consistently outperforming either alone. This demo shows which results come from each method and how RRF merges the rankings.
BM25 results: exact term frequency and inverse document frequency scoring shown per result
Dense retrieval results: cosine similarity to query embedding ranked separately
RRF merging: 1/(k + rank) scores from both lists summed and re-sorted into final ranking
Unique hits: results that only BM25 or only dense retrieval finds, highlighted in the merge
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