(stage-1) Dense query DPR Reranker model [11,12] (stage-2) top-100 top-200 MonoT5 query: *** doc: ### label: {True, False} Sparse BM25 FiD ・・・ - softmax only on the logits of the label tokens. - rerank according to the probabilities assigned to the “true” token. Scheme for improving retriever: multi-stage retrieval pipeline