When wealth inequality widens, the stability of the entire society is shaken.

In math class, I learned about the concept of intersection.

In math class, we learned about the concept of union.

The concept of the absolute complement plays an important role in set theory.

He wants to learn deeply about set theory.

Set operation is one of the basic concepts in mathematics.

He is learning how to use collective nouns.

In mathematics, an empty set refers to a set that does not contain any elements.

A power set is a set consisting of all subsets of a set.

In math class, we learned about the intersection.