Define empty set .

Answer

**Step-by-Step Text Solution:**

1. **Definition of an Empty Set**: An empty set is defined as a set that contains no elements. In mathematical terms, it is a set with a cardinality (number of elements) of zero.

2. **Representation**: The empty set is commonly represented by the symbol ∅ or by a pair of curly brackets with no elements inside, like this: {}.

3. **Characteristics**: The empty set is unique in that it is the only set that has no elements. It is a subset of every set, meaning that for any set A, the empty set is considered to be a part of A.

4. **Example**: For instance, if we have a set A defined as A = {}, then A is an empty set because it contains no elements.

5. **Conclusion**: Therefore, the empty set is a fundamental concept in set theory, representing the idea of "nothing" or "no elements."

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