2.3 Truth values

We will want to distinguish between statements that are true and statements that are false. Another fundamental form of data allows us to do this. This form of data consists of just two values, which we shall write as true and false.
Not all texts use the same notation: some use T and F; others may use 0 for false and 1 for true (or the reverse!).
We may refer to true and false as truth values, or Boolean values. We will denote the collection (set) of truth values as Bool, after the mathematician George Boole. We write:

Bool = {true, false}.

This shows the collection Bool as a set. We have already mentioned the word set in passing, and now want to look at this concept in more detail.