The statements that describe valid input are known as preconditions and the conditions that the output should satisfy when the program has run are known as postconditions. Universal quantification, which tells us that a predicate is true for every el…
DEFINITION 1 A compound proposition that is always true,no matter what the truth values of the proposi-tional variables that occur in it, is called atautology. A compound proposition that is always false iscalled a contradiction. A compound propositi…
propositional variables (or statement variables), letters used for propositional variables are p, q, r, s, . . . . The truth value of a proposition is true, denoted by T, if it is a true proposition, and the truth value of a proposition is false, den…