Chapter 1 What is a Venn diagram?

A venn diagram is a deceptively simple figure, intended to compare two or more sets in a visually intuitive way.

Each set is represented by a circle, drawn with a label beside it. Two circles are shown below for sets A and B, and these circles are drawn so they partially overlap.

The overlapping region represents the intersection of sets A and B. Using mathematical symbols, the intersect is written \(A∩B\), but we use A&B for convenience since the symbol \(∩\) does not exist on most computer keyboards.

A simple Venn diagram is shown with two sets: A and B.

Figure 1.1: A simple Venn diagram is shown with two sets: A and B.

The numbers in the Venn diagram represent the number of items in each logical grouping:

  • '5' is the number of items in 'A' and 'not B'.
  • '3' is the number of items in 'B' and 'not A'.
  • '2' is the number of items in 'A' and 'B'.