Using the De Morgan Rule
!(A && B)is equivalent to!A || !B
the original expression
boolean reject = !(speed > 2000 && memory > 512)
is equivalent to
boolean reject = !(speed > 2000) || !(memory > 512)
which is equivalent to
boolean reject = (speed <= 2000) || (memory <= 512)
Here is the other De Morgan rule:
!(A || B)is equivalent to!A && !B
This truth table shows why this rule is true.
The fourth and the last column have the same truth values, which shows that the expressions at the top of those columns are equivalent.
| A | B | (A || B) | !(A || B) | !A | !B | !A && !B |
|---|---|---|---|---|---|---|
| F | F | F | T | T | T | T |
| F | T | T | F | T | F | F |
| T | F | T | F | F | T | F |
| T | T | T | F | F | F | F |
Rewrite the following fragment:
while ( !(input.equals( "quit" ) || (count > limit)) )
{
. . .
}