“…Early research in QPP utilizes linguistic information [29], statistical features [15,23,24] in pre-retrieval methods, or analyses clarity [15,16], robustness [7,20,48,54,55], retrieval scores [34,41,44,47,55] for post-retrieval prediction, which further evolves into several effective frameworks [17,20,28,38,40,45,46]. The QPP techniques have also been explored and analyzed in [3,5,6,10,18,21,22,25,35,36,39,42,43,52,53,27]. With the recent development deep learning techniques, NeuralQPP [51] achieves promising results by training a three-components deep network under weak supervision of existing methods.…”