In number theory or arithmetic we can use operations such as addition, subtraction, multiplication and division. In set theory the operations are union, intersection, difference. Some of them defined in the previous post. In this post, we will talk about results for operations between sets. Difference between sets Initially, let’s talk about the difference between sets. To do this, the following definition follows: Definition (Difference between sets): Let A and B be two sets, let us denote the difference between the sets $A$ and $B,$ by $A \setminus B$ or $A−B,$ is the set formed by the elements that are in $A$ and are not in $B.$. Symbolically, we write: $$A - B = \\{x; \quad x \in A \wedge x \notin B\\}.$$