Venn diagrams part two

We are going to look at Venn Diagrams in a little more detail. I’m going to use an example to illustrate these simple depictions of classifying information into sets and then we will look at more general rules.

Often in Venn Diagrams sets are shown within a rectangular box. This box contains the universal set and is represented by an epsilon symbol which is the fifth letter of the Greek alphabet. The word universe means entire or all. The universal set is all the events we are considering. For example, if we are considering a card selected from a pack of cards then the universal set is all cards. If we are considering numbers from 1 to 10 then the universal set contains all of these numbers and .

Within the universe we are considering, let’s create two sets, numbers under 6 and numbers from 5 to 9. Let’s label these sets A and B.

Let’s show these sets within the universal set.

We can see that the intersection of A and B is 5. The union of A and B is {1, 2, 3, 4, 5, 6, 7, 8, 9}.

The compliment of a set is everything that is in the universal set but not in the set in question. The complement of set A is written as A^c

In our example