Empty set: A set without any elements is called an empty set.

Subset: For two sets A and B, if any element of set A is an element of set B, we say that set A is contained in set B, or set B contains set A, which means that set A is a subset of set B. ..

Proper subset: If any element in set A is an element in set B and at least one element in set B does not belong to set A, then set A is called the proper subset of set B.

An empty set is a subset of any set and a proper subset of any non-empty set. Any set is a subset of itself.

Simply put, if you draw a big circle to represent the whole set, then the subset is a circle less than or equal to it, and the proper subset is a circle that must be less than it.

I hope the answer will help you.

Author: Doll 2.5+ Meng Jing

20 10.9. 10