## Invitation to Computer Science 8th Edition

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.