BM25opt is a score-compatible optimized rewrite of the popular <a href="https://github.com/dorianbrown/rank_bm25">https://github.com/dorianbrown/rank_bm25</a> , which is used by e.g. LangChain and Llamaindex. It's much faster and tries to fix some issues as well.<p><a href="https://en.wikipedia.org/wiki/Okapi_BM25" rel="nofollow">https://en.wikipedia.org/wiki/Okapi_BM25</a>