However, it also gives the upper bound of performance of a discretized gw.lw combination assuming that the loss due to discretization is negligible which can be easily attained by using sufficiently large number of bins.
the results indicate that gw.lw, which includes practically all the popular "bag of words" ranking formulas such as tf.idf, BM25 or language models, has almost reached its upper limit and other classes of representations and ranking formulas need to be explored to attempt greater improvements.