And v(g) can be intuitively interpreted as the group averaged sub-gradient of In addition, an intuitive explanation of merging loop is that the value of objective in Eq.4 will be decreased after each merging step in line 6.
in summary, if we use a sparse representation for vector a in Algorithm 3, then its complexity is O |∆(a)|log(|∆(a)|) , which is independent of d. the whole tuning algorithm (Algorithm 1) with feature grouping is efficient even with a large value of d. We conduct experiments on the iWSLT2008 Chinese-to-English translation tasks, whose training data consists of about 30K bilingual sentence 3 The reason is attributed to the Eq.5 in (Zhong and Kwok, 2011).