C2C Trace Retrieval: Fast Classification Using Class-to-Class Weighting

Traditional case-based classification methods are based on feature similarity. In contrast, class-to-class (C2C) weighting also considers whether the difference between two cases has been seen before. Combined with instance-specific weighting, C2C weighting learns the local patterns of both similarities and differences (shortened as patterns). Once C2C weightings has learned the pattern between case A of class C_1 and some set of cases R of class C_2, given a query Q whose difference from A matches the pattern between A and R, then we can skip cases around A and continue the search for near neighbors around R. Based on this, we developed an algorithm, C2C trace retrieval, which quickly traverses promising cases, retrieves relevant cases from different classes, and provides an informed hypothesis of the query's class. C2C trace retrieval achieves great efficiency at a reasonable cost of accuracy. Therefore, C2C trace retrieval can be used as a fast classification method or as the first pass for a more sophisticated method.