A fully connected layer with a twoclass softmax function is used to determine the quality of entity proposals: where W p ∈ R 2D sl ×2R and b p ∈ R 2R are weights and the bias for the entity proposal layer; s k contains 2R scores including R scores for being an entity and R scores for not being an entity at position k. The cross-entropy loss is employed in the Detector as follows: where y r k is the label for proposal type r at position k and s r k is the probability of being an entity for proposal type r at position k. It is worth mentioning that, most entity proposals are negative proposals.
to balance the influence of positive proposals and negative proposals in the loss function, we keep all positive proposals and use down-sampling for negative proposals when calculating the loss L p .