1. Frequent Pattern Mining.pdf

Definition of Sets A set is a collection of objects (e.g., s = {1, 4, 9}). ► The objects are said to be elements of the set (e.g., 1 Es, 4 Es, 9 E S). Each element is unique. We can define sets extensionally: by enumerating the elements that define the set (e.g., s = {1, 4, 9}). intensiona...

Definition of Sets A set is a collection of objects (e.g., s = {1, 4, 9}). ► The objects are said to be elements of the set (e.g., 1 Es, 4 Es, 9 E S). Each element is unique. We can define sets extensionally: by enumerating the elements that define the set (e.g., s = {1, 4, 9}). intensionally: by characterizing the elements of the set, ► describing what condition (the "characteristic function" of the set) holds for all the elements and only for the elements of the set (e.g. S = {xlJ.x EN ANDx < 1 5 } - read 'I' as 'for which holds' or 'such that'). ► The intensional definition typically resorts to a domain over which the set is defined (here: N).