(2016) partially motivate the ranking-based variant throught the importance sampling viewpoint of Bengio and Senécal (2008).
there are two critical differences: 1) the algorithm of Bengio and Senécal (2008) does not lead to the same objective L n R in the ranking-based variant of NCE; instead it uses importance sampling to derive an objective that is similar but not identical; 2) the importance sampling method leads to a biased estimate of the gradients of the log-likelihood function, with the bias going to zero only as K !