A Level Computer Science OCR Practice Exam

What does the general rule Av¬A signify?

1. False

2. True

3. Undefined

4. None

The correct answer is: True

The expression Av¬A is a fundamental principle in logic known as the Law of Excluded Middle. This law states that for any proposition A, either A is true or its negation (¬A) is true. There is no middle ground; hence, one of these must hold true. In practical terms, this means that every statement must be either true or false. Therefore, the expression Av¬A is always true, since at least one of the components (A or its negation) must be true. This principle serves as a foundational aspect of classical logic and is crucial for reasoning, proof construction, and various computational processes that rely on binary logic. While some logical systems might explore other values (like undefined) in specific contexts, within the framework of classical propositional logic, Av¬A will consistently evaluate to true. This clarity helps in establishing reliable logical structures and arguments in computer science and mathematics.