A method used to represent a set in which we state one or more characteristic properties of the elements so that one is able to decide whether a given object is an element of the set

Explanation

If D is a set such that its elements x satisfy the property P(x), then we write D = { x|x satisfies P(x) }.

Examples:

• A = {x|x is even integer} = { ..., 4, 2, 0, 2, 4, 6, ... }
• B = { x|x is odd number less than 11 } = { 1,2,3,5,7,9 }
• C = The set of roots of the equation x³ - 6x² + 11x - 6 = 0
  = { x|x³ - 6x² + 11x - 6 }.  Now, since the roots of the equation x³ - 6x² + 11x - 6 are 1, 2, and 3, we may write C = {1, 2, 3}