Unveiling the Mysteries: Exploring the Intricacies of Higher-Order Sets

Getting Started

In set theory, a discipline that forms the foundation of mathematics, sets are fundamental objects that allow us to classify and organize elements into distinct groups. Sets can contain any number of elements, including other sets. When a set itself consists of multiple sets, an intriguing question arises: What is a set of sets called? In this article, we will explore this concept and delve into the fascinating world of sets within sets.

Understanding sets

Before we can grasp the notion of a set of sets, it is crucial to have a solid understanding of sets themselves. In set theory, a set is a well-defined collection of distinct objects, called elements or members, which can be anything from numbers to letters or even other sets. For example, let’s look at the following sets:

Set A:

Set B:

Set C:

Here, Set A and Set B consist of individual elements, while Set C contains two sets, namely Set A and Set B. This brings us to the concept of a set of sets.

The Power Set

A set that contains all possible subsets of a given set is called a power set. In other words, the power set of a set is the collection of all possible combinations of its elements, including the empty set and the set itself. If we denote a set as S, then the power set of S is denoted as P(S).

For example, let’s consider the set S = . The power set of S, denoted P(S), would be , , , , }. Here, the power set contains four subsets: the empty set , the sets and , and the set .

Note that the power set of any set always has 2^n elements, where n is the number of elements in the original set. Thus, if a set contains ‘n’ elements, its power set will contain 2^n subsets.

Nesting of sets

In some cases, sets can be nested, forming a hierarchical structure. When a set contains other sets as its elements, it is called a nested set or a set of sets. This nesting can occur at any level, allowing for complex and intricate relationships between sets.

For example, let’s consider the following sets:

Set X:

Set Y:

Set Z:
Here, Set Z is a set of sets because it contains Set X and Set Y as elements. In this nested structure, Set Z is a parent set, while Set X and Set Y are considered child sets.

Alternative terminology

While there is no universally accepted term for a set of sets, it is worth mentioning some alternative terminologies that are used in different contexts. One common term is a “family of sets,” which refers to a collection of sets. This term emphasizes the collective nature of the sets within the group.

Another term sometimes used is a “collection of sets”. This terminology is more general and does not necessarily imply a hierarchical relationship between the sets in question. It is often used to describe a group of sets that share certain properties or characteristics.

In set theory, a power set is a fascinating concept that allows sets to be nested within each other. While there is no specific, universally accepted term to describe a set of sets, the power set provides a way to represent all possible subsets of a given set. The nesting of sets opens up a world of possibilities for organizing and categorizing elements, allowing for intricate relationships and structures in mathematics and beyond. By understanding the fundamentals of sets and their nesting, we can gain deeper insights into the underlying structure of mathematical concepts and scientific phenomena.


What is a set of sets called?

A set of sets is called a “power set” or “set of subsets”.

How is a power set defined?

A power set is defined as the collection of all possible subsets of a given set.

What is the cardinality of a power set?

The cardinality of a power set is equal to 2 raised to the power of the cardinality of the original set. In other words, if a set has n elements, its power set will have 2^n elements.

Can a set be an element of its own power set?

Yes, a set can be an element of its own power set. The power set of any set includes both the set itself and the empty set.

Can a power set be empty?

Yes, a power set can be empty if the original set is also empty. In that case, the power set will contain only the empty set.

How do you represent a power set?

A power set is often denoted using the notation P(S), where S is the original set. Alternatively, you can use the notation 2^S to represent the power set, emphasizing the relationship between the cardinality of the set and its power set.