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

In math class, we learned about the intersection.

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

There is a communal letterbox in our apartment.

In mathematics, a mapping represents a correspondence from one set to another.

He showed his gratitude on his face.

He has difficulty expressing his emotions in words.

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

She has trypophobia, and feels discomfort when she sees things with many holes like beehives or corals.

He ate one apple.