Let's gather with friends at the park.

In set theory, the symmetric difference indicates the difference between two sets.

In math class, the teacher explained the concept of relative complement.

It was decided that friends would gather in the park.

He wants to learn deeply about set theory.

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

He is learning how to use collective nouns.

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

In math class, we learned about the intersection.

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