Sets

A set is a well

A set is a well-defined collection of distinct objects called elements. For a collection to be a set, we must be able to definitively determine whethe

Elements are the individual objects

Elements are the individual objects in a set. If an element 'a' belongs to set A, we write 'a ∈ A' (read as 'a is an element of A' or 'a belongs to A'

In the listing method

In the listing method, we write all elements of a set inside curly brackets {}, separated by commas. Each element is written only once, regardless of

In the rule method

In the rule method, we describe a set using a variable and a condition. The format is: A = {x | condition on x} (read as 'A is the set of all x such t

An empty set (or null set)

An empty set (or null set) is a set that contains no elements. It is denoted by { } or φ (phi). For example, the set of natural numbers less than 1 is