Inspired by the non-maximum suppression (NMS) algorithm (Rosenfeld and Thurston, 1971) that is used to prune redundant bounding boxes in object detection (Ren et al., 2015), we present a span-level NMS (Algorithm 1) to alleviate the problem.
span-level NMS starts with a set of candidate answers A with scores S. After selecting the answer a i that possesses the maximum score, we remove it from the set A and add it to B.