An example of a Tautology is:
2008
An example of a Tautology is:
- A.
x ∨ y
- B.
x ∨ ¬y
- C.
x ∨ ¬x
- D.
(x → y) ∧ (y → x)
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Correct answer: C
A tautology is a proposition that is always true for all truth values.
Expression:
x∨¬x
is always true because either xxx is true or ¬x is true.
This is called the Law of Excluded Middle.
Hence, it is a tautology.
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