The Truth Table is as follows.
p
q
p q
⇒
T
T
T
T
F
F
F
T
T
F
F
T
18. What is the Truth Table of Biconditional?
Biconditional means “q if and only if p”. or “p is equivalent to q”.
p
q
p q
⇔
T
T
T
T
F
F
F
T
F
F
F
T
19. What do you mean by Tautology?
A Tautology is a propositional form whose truth value is true for all
possible values of its propositional variables.
Example: P
P
∨ ¬ .
20. What do you mean by contradiction?
A contradiction or absurdity is a propositional form which is always
false.
Example: P
P
∧ ¬ .
21. What do you mean by contingency?
A propositional form which is neither a tautology nor a contradiction
is called a contingency.
22. What are the representations for tautology and contradiction?
Tautology → 1
Contradiction → 0.
23. What is Modus Ponens?
[
(
)]
P P Q
Q
∧
⇒
⇒
24. What is Modus Tollens?
[(
)
]
.
P Q
Q
P
⇒ ∧ ¬ ⇒ ¬
Prop o si tions and Pred i cates
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