Chapter 4 - 4.3 - Boolean Logic and Gates - Practice Problems - Page 187: 6

The expression $(A \text { OR } B)$ OR (NOT $A )$ is true for all values of $A$ and $B$ and, therefore, is never false. A Boolean expression that is always true is called a tautology.

The expression $(A \text { OR } B)$ OR (NOT $A )$ is true for all values of $A$ and $B$ and, therefore, is never false. A Boolean expression that is always true is called a tautology.