Abstract Based on logical similarity and residual implications, the paper discusses the robust-
ness of two important reasoning methods, the ˉve implication inference method (QIP) and the similarity
inference method (FSI). The concrete results of the robustness of QIP method under four common im-
plications are given, based on the revised Kleene implication the FSI's robustness conclusion, and a
preliminary comparison of the robustness of these two inference methods.
