Given a paraphrased sentence T, which consists of J words, the novelty function Novel(TM,T,n,j) judges whether the occurrence of t j generates a new n-gram to the translation model (TM) according to the prior n-1 words of t j .
formally, the novel function for position j can be defined as: the novelty model for a paraphrased sentence T, considering the novelty of 1-gram to Ngram (N=4 in this work), is computed as: where ߣ is the weight for the novelty model, Now we can describe the complete formula of the SPG framework as: We enhance the SMT model by expanding the training corpus using paraphrases.