Fig. 4

The negative example set N ₂ is obtained with the second iteration In figure 4, plus signs, plus signs with circle and circles denote positive examples, potential positive examples and unlabeled examples respectively. The points covered by ellipse are negative example set N₂ and the line is classification hyperplane.With the new training set ∪ N₁, the SVM classifier C₁ is learned, the negative example set N₂ consists of the support vectors of C₁ and the unlabeled examples predicted as negative examples.