Hard Negative Mining for Embedding Model Training
A practical guide to hard negative mining for ML engineers training embedding models: why random negatives produce weak gradient signal, BM25-mined hard negatives with rank_bm25, embedding-mined negatives with FAISS and sentence-transformers, cross-encoder filtering to identify the hardest candidates, training with MultipleNegativesRankingLoss, and iterative mining pipelines used by state-of-the-art models like E5 and BGE.