# What is an Empty Set or Null Set?

A short tutorial that explains the definition of empty set with example.

## Elementary Set Theory

Empty set is also referred as Null set. It is a set without any elements. Typically, a set refers to the collection of individual elements. The empty set is represented by the open and closed curly braces symbol as shown { }. Alternatively the symbol "**Ø **"(known as minuscule) is also used to refer the Empty set. The below tutorial explains elementary set theory and what is an empty set or null set.

**Cardinality **

Cardinality refers to the total number of elements in a set. For example, consider the set of vowels. Let it be called as Set A.

Hence, Set A = {a, e, i, o, u}

Its has a cardinality of 5, as the set A has five elements in it. It can be written as,

|A| = 5

**Cardinality **of the Empty Set

The Cardinality of the empty set is Zero as the set contains no elements. Using proper set notation, we can write down as

|**Ø| = 0**

**Practical Example of Empty Set**

The set of cows with 10 legs.

The set of numbers that is both even and odd.

**Example:**

Mathematically, lets consider an example. Find A intersection B** (A ∩ B)**.

A = {m, n, o, p}

B = {d, y, v, e}

Intersection of the two set is about finding the elements that are present in both the set A and B.

Here in the given example, the intersection of A and B is none. So we can write it down as

**A ∩ B = { }**.

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