Discrete Mathematical Structures by Pearson

4-4 Discrete Mathematical Structures

4.4.1 Negation

If p is a statement, then negation of p is a statement not p. The negation of statement. “x equal to

d ” is the statement “x does not equal to d ”. Thus, negation of “x = d ”is x ≠ d.

The truth table of ∼p relative to p is as follows: Strictly speaking, negation is not connective

as it does not combine two statements. In fact, negation is a unary operation for the statements.

Further, double negation is positive. Table 4.1 shows truth table for negation.

Table 4.1 Truth table for negation (∼)

p

∼p

T F

F T

Table 4.2 Truth table for double negation

p

∼p ∼(∼p)

T F T

F T F

Table 4.2 shows that double negation ...