A Level Computer Science OCR Practice Exam

What happens when there are two NOTs applied in boolean logic?

1. It simplifies to Positive

2. It simplifies to Negative

3. It leads to Undefined

4. It cancels out

The correct answer is: It cancels out

In boolean logic, applying two NOT operations to a variable effectively negates it twice. This process of negation means that the first NOT flip the state of the variable (for example, from true to false, or from false to true), and when the second NOT is applied, it flips the state again, returning it to its original value. For instance, if the original value of a variable A is true (1), applying the first NOT results in false (0). Applying the second NOT returns it back to true (1). Thus, two NOT operations cancel each other out, leading to the conclusion that the result of applying two NOTs is equivalent to the original value. This behavior is a fundamental principle in boolean algebra, demonstrating the redundancy of applying two negations. It ensures that after the two operations, you end up with the same logical state you started with. Therefore, the notion of "cancelling out" correctly describes the operational outcome of this scenario.