The document discusses finding the optimal parameter K for the emerging pattern-based classifier PCL. PCL selects the top-K emerging patterns from each class that match a test instance and uses these patterns to predict the class label. The authors develop an algorithm to determine the best value of K for PCL on different datasets, as K's optimal value varies. They sample subsets of training data to find the K that performs best on average, maximizing the likelihood of good performance on the whole dataset. Experimental results show that finding the best K improves PCL's accuracy and that using incremental frequent pattern maintenance techniques speeds up the algorithm significantly.