Papers › Salient Phrase Aware Dense Retrieval: Can a Dense Retriever Imitate a Sparse One?

Salient Phrase Aware Dense Retrieval: Can a Dense Retriever Imitate a Sparse One?

13 Oct 2021arXiv:2110.06918archive 2025-07-28

Xilun Chen, Kushal Lakhotia, Barlas Oğuz, Anchit Gupta, Patrick Lewis, Stan Peshterliev, Yashar Mehdad, Sonal Gupta, Wen-tau Yih

Despite their recent popularity and well-known advantages, dense retrievers still lag behind sparse methods such as BM25 in their ability to reliably match salient phrases and rare entities in the query and to generalize to out-of-domain data. It has been argued that this is an inherent limitation of dense models. We rebut this claim by introducing the Salient Phrase Aware Retriever (SPAR), a dense retriever with the lexical matching capacity of a sparse model. We show that a dense Lexical Model {\Lambda} can be trained to imitate a sparse one, and SPAR is built by augmenting a standard dense retriever with {\Lambda}. Empirically, SPAR shows superior performance on a range of tasks including five question answering datasets, MS MARCO passage retrieval, as well as the EntityQuestions and BEIR benchmarks for out-of-domain evaluation, exceeding the performance of state-of-the-art dense and sparse retrievers. The code and models of SPAR are available at: https://github.com/facebookresearch/dpr-scale/tree/main/spar

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Tasks

Open-Domain Question AnsweringPassage RetrievalQuestion AnsweringRetrieval

Results from the paper archive 2025-07-28

TaskDatasetModelMetricValueRank at snapshotLeaderboardReport
Passage Retrieval EntityQuestions SPAR-PAQ Recall@20 0.740 #2 of 7 Archive leaderboard report
Passage Retrieval Natural Questions SPAR Precision@100 88.8 #3 of 10 Archive leaderboard report

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