It is a domain knowledge that is used to guide the search or evaluate the interestingness of resulting patterns.
Such knowledge can include concept hierarchies, used to organize attributes or attribute values into different levels
of abstraction. Knowledge such as user beliefs, which can be used to assess a pattern’s interestingness based on its
unexpectedness, may also be included. Other examples of domain knowledge are additional interestingness
constraints or thresholds, and metadata (e.g., describing data from multiple heterogeneous sources). Here,
Knowledge Base is created in four steps as follows.