Using RF, MR-PN (RF on MR with positive and
negative examples) and MR-P (MR with positive
examples) receive greater improvement than does the
original MR method, as shown in Fig. 4. However,
the difference between MR-PN and MR-P is not
very clear, meaning that the influence of positive and
negative examples is uncertain. RF is not applied on
other methods since it cannot be designed easily for
traditional similarity matching.