Perform intra-strata sampling to form SeedSET i from each stratum RSET i , by selecting the center C i and (N i -1) additional instances Generate SeedSET by summating RSET i from each stratum Nevertheless, remember the fact that, this time for the stratum RSET i , the center C i has been chosen, so it may not be reasonable to extract additional centers in this way.
in order to avoid recursion and over-complexity, we employ a diversity-motivated intra-stratum sampling scheme (Shen et al., 2004), called KDN (K-diverse neighbors), which aims to maximize the training utility of all seeds from a stratum.