Probability
- 內容
Basic Set Theory Definition:
A set is a well-defined collection of objects. The capital letters A, B, C ... represent sets whereas a, b, c, ... denote their elements. We can have finite or infinite sets. Example - If A is a set consisting of the squares of the integers 1, 4, 5, 7, it will contain 4 elements and can be written as A = {1, 16, 25, 49} (elements in any order) = {x2 | x = 1, 3, 5, 7,} A is finite whereas B = {1, 3, 5, 7, 9, ...} is infinite. We denote elements as x 0 A. For example, 16 0 A but 4 ó A. Definition: A set containing no elements is called the null set denoted by i. Example -{x|(x-1)2 <0} = i Definition: A set A is called a subset of B if every element of a set A is also an element of a set B and is denoted as A d B. Example - For A = {1, 16, 25, 49}, {1} d A, {1, 49} d A, i d A.