Exercise 1.4¶
Here is a truth table which might help you understand why the first of De Morgan’s laws is true:
| \(P\) | \(Q\) | \(P \land Q\) | \(\neg (P \land Q)\) | \(\neg P\) | \(\neg Q\) | \(\neg P \lor \neg Q\) |
|---|---|---|---|---|---|---|
| T | T | T | F | F | F | F |
| T | F | F | T | F | T | T |
| F | T | F | T | T | F | T |
| F | F | T | T | T | T | T |
Another truth table can be constructed for the other law in a similar way.