## TAUTOLOGY

### Tautology

In logic, a**tautology**is a formula which is true in every possible interpretation. Philosopher Ludwig Wittgenstein first applied the term to redundancies of propositional logic in 1921; it had been used earlier to refer to rhetorical tautologies, and continues to be used in that alternate sense.

*The above text is a snippet from Wikipedia: Tautology (logic)*

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### tautology

#### Noun

- redundant use of words
*It is***tautology**to say, "Forward Planning".

- An expression that features tautology.
- ''The expression "raze to the ground" is a tautology, since the word "raze" includes the notion "to the ground".

- A statement that is true for all values of its variables
*Given a Boolean A, "A OR (NOT A)" is a***tautology**.*A logical statement which is neither a***tautology**nor a contradiction is a contingency.*A***tautology**can be verified by constructing a truth tree for its negation: if all of the leaf nodes of such truth tree end in X's, then the original (pre-negated) formula is a**tautology**.

*The above text is a snippet from Wiktionary: tautology*

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and as such is available under the Creative Commons Attribution/Share-Alike License.