> Unfortunately, inherent complexities in the data generation of these processes, combined with imperfections in the measurement systems as well as interactions

> Unfortunately, inherent complexities in the data generation of these processes, combined with imperfections in the measurement systems as well as interactions with malicious actors, often result in abnormal phenomena. Such abnormal events appear subsequently in the collected data as anomalies. This is critical; and difficult to deal with in many instances. > With the term anomalies we refer to data points or groups of data points that do not conform to some notion of normality or an expected behavior based on previously observed data. This is a key problem or perhaps the problem: rigorously or precisely defining what an anomaly is and is not.