Define Tautology and Contradiction in Discrete Mathematics
A compound proposition that is always true for all possible truth values of its variables or, in other words, contains only T in the last column of its truth table is called a Tautology.
A compound proposition that is always false for all possible values of its variables or, in other words, contains only F in the last column of its truth table is called a contradiction. Finally, a proposition that is nether a tautology nor a contradiction is called a contingency.
1. The professor is either a woman or a man.
2. People either like watching TV or they don’t
are always true and are called tautologies.
1. x is prime and x is an even integer greater than 8.
2. All men are good and all men are bad
are always false and are called contradictions.