# DPR

## Overview Dense Passage Retrieval (DPR) is a set of tools and models for state-of-the-art open-domain Q&A research. It was introduced in [Dense Passage Retrieval for Open-Domain Question Answering](https://arxiv.org/abs/2004.04906) by Vladimir Karpukhin, Barlas Oğuz, Sewon Min, Patrick Lewis, Ledell Wu, Sergey Edunov, Danqi Chen, Wen-tau Yih. The abstract from the paper is the following: *Open-domain question answering relies on efficient passage retrieval to select candidate contexts, where traditional sparse vector space models, such as TF-IDF or BM25, are the de facto method. In this work, we show that retrieval can be practically implemented using dense representations alone, where embeddings are learned from a small number of questions and passages by a simple dual-encoder framework. When evaluated on a wide range of open-domain QA datasets, our dense retriever outperforms a strong Lucene-BM25 system largely by 9%-19% absolute in terms of top-20 passage retrieval accuracy, and helps our end-to-end QA system establish new state-of-the-art on multiple open-domain QA benchmarks.* This model was contributed by [lhoestq](https://huggingface.co/lhoestq). The original code can be found [here](https://github.com/facebookresearch/DPR). Tips: - DPR consists in three models: * Question encoder: encode questions as vectors * Context encoder: encode contexts as vectors * Reader: extract the answer of the questions inside retrieved contexts, along with a relevance score (high if the inferred span actually answers the question). ## DPRConfig [[autodoc]] DPRConfig ## DPRContextEncoderTokenizer [[autodoc]] DPRContextEncoderTokenizer ## DPRContextEncoderTokenizerFast [[autodoc]] DPRContextEncoderTokenizerFast ## DPRQuestionEncoderTokenizer [[autodoc]] DPRQuestionEncoderTokenizer ## DPRQuestionEncoderTokenizerFast [[autodoc]] DPRQuestionEncoderTokenizerFast ## DPRReaderTokenizer [[autodoc]] DPRReaderTokenizer ## DPRReaderTokenizerFast [[autodoc]] DPRReaderTokenizerFast ## DPR specific outputs [[autodoc]] models.dpr.modeling_dpr.DPRContextEncoderOutput [[autodoc]] models.dpr.modeling_dpr.DPRQuestionEncoderOutput [[autodoc]] models.dpr.modeling_dpr.DPRReaderOutput ## DPRContextEncoder [[autodoc]] DPRContextEncoder - forward ## DPRQuestionEncoder [[autodoc]] DPRQuestionEncoder - forward ## DPRReader [[autodoc]] DPRReader - forward ## TFDPRContextEncoder [[autodoc]] TFDPRContextEncoder - call ## TFDPRQuestionEncoder [[autodoc]] TFDPRQuestionEncoder - call ## TFDPRReader [[autodoc]] TFDPRReader - call