Construct a truth table for ~(pÙq)
Start out with this table:
_______________________
| p | q | pÙq | ~(pÙq) |
case 1 | T | T | | |
case 2 | T | F | | |
case 3 | F | T | | |
case 4 | F | F | | |
(Rule for "AND", Ù:
Ù requires truth on both sides in
order to be true)
in case 1, p has value T and q has value T, so
Ù has trues on both sides so we put a T under pÙq
in case 1.
_______________________
| p | q | pÙq | ~(pÙq) |
case 1 | T | T | T | |
case 2 | T | F | | |
case 3 | F | T | | |
case 4 | F | F | | |
in case 2, p has value T and q has value F, so
Ù does NOT have trues on both sides so we put a
F under pÙq in case 2.
_______________________
| p | q | pÙq | ~(pÙq) |
case 1 | T | T | T | |
case 2 | T | F | F | |
case 3 | F | T | | |
case 4 | F | F | | |
in case 3, p has value F and q has value T, so
Ù does NOT have trues on both sides so we put a
F under pÙq in case 3.
_______________________
| p | q | pÙq | ~(pÙq) |
case 1 | T | T | T | |
case 2 | T | F | F | |
case 3 | F | T | F | |
case 4 | F | F | | |
in case 4, p has value F and q has value F, so
Ù does NOT have trues on both sides so we put a
F under pÙq in case 4.
_______________________
| p | q | pÙq | ~(pÙq) |
case 1 | T | T | T | |
case 2 | T | F | F | |
case 3 | F | T | F | |
case 4 | F | F | F | |
Now we fill in the column under ~(pÙq)
(Rule: "NOT" means to give the opposite
value of what follows the symbol "~". That
is, if ~ precedes T, then that gives F and
if ~ precedes F, then that gives T)
Since in case 1, pÙq has value T, then
~(pÙq) will have the opposite value F:
_______________________
| p | q | pÙq | ~(pÙq) |
case 1 | T | T | T | F |
case 2 | T | F | F | |
case 3 | F | T | F | |
case 4 | F | F | F | |
Since in case 2, pÙq has value F, then
~(pÙq) will have the opposite value T:
_______________________
| p | q | pÙq | ~(pÙq) |
case 1 | T | T | T | F |
case 2 | T | F | F | T |
case 3 | F | T | F | |
case 4 | F | F | F | |
Since in case 3, pÙq has value F, then
~(pÙq) will have the opposite value T:
_______________________
| p | q | pÙq | ~(pÙq) |
case 1 | T | T | T | F |
case 2 | T | F | F | T |
case 3 | F | T | F | T |
case 4 | F | F | F | |
Since in case 4, pÙq has value F, then
~(pÙq) will have the opposite value T:
_______________________
| p | q | pÙq | ~(pÙq) |
case 1 | T | T | T | F |
case 2 | T | F | F | T |
case 3 | F | T | F | T |
case 4 | F | F | F | T |
So the truth table for ~(pÙq) is FTTT
Edwin