What is the set of 𝑋 minus the set of 𝑋?
The set 𝑋 is a collection. Inside each of these sets is the same value. Imagine if the set of 𝑋 contained five. Then what we’re saying is the set of five minus the set of five.
And that would leave us with an empty set. There would be nothing in there. And the notation for an empty set or the null set looks like this.
The set of 𝑋 Minus the set of 𝑋 equals the empty set, and we write the empty set with this symbol.