Resolution:
## Fig. 5.
Obtaining the negative example set In figure 5, 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 N_{3} with the more iterationN_{3} and the line is classification hyperplane.With the new negative example set N_{2}, the SVM classifier C_{2} is learned, the negative example set N_{3} consists of the support vectors of C_{2}> and the unlabeled examples predicted as negative examples. The process can proceed
until the condition |U| ≤ 4 * || is meet.
Chen |