code: public static synchronized XEventClasses deriveEventClasses(
  			XEventClassifier classifier, XLog log) {
  		XEventClasses nClasses = new XEventClasses(classifier);
  		nClasses.register(log);
  		nClasses.harmonizeIndices();
  		return nClasses;
  	}
docs: Creates a new set of event classes, factory method.
  
  @param classifier
  The classifier to be used for event comparison.
  @param log
  The log, on which event classes should be imposed.
  @return A set of event classes, as an instance of this class.