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truth table (Definition)

A truth table is a tabular listing of all possible input value combinations for a logical function and their corresponding output values. Similarly, the truth table of a logical proposition is the truth table of the corresponding logical function.

For instance, the truth table of the connective “or” is as follows:

$ a$ $ b$ $ a \lor b$
F F F
F T T
T F T
T T T

For $ n$ input variables, there will always be $ 2^n$ rows in the truth table. A sample truth table for “ $ (a \land b) \rightarrow c$” would be

$ a$ $ b$ $ c$ $ (a \land b) \rightarrow c$
F F F T
F F T F
F T F T
F T T F
T F F T
T F T F
T T F T
T T T T

(Note that $ \land$ represents logical and, while $ \rightarrow$ represents the conditional truth function).

To compute truth tables of expressions, one often proceeds in steps. for instance, to compute a truth table for “ $ \neg p \lor (p \land q)$, one might proceed as follows:

$ p$ $ q$ $ \neg p$ $ (p \land q)$ $ \neg p \lor (p \land q)$
F F T F T
F T T F T
T F F F F
T T F T T

For reference, here is a truth table of some popular connectives:

$ p$ $ q$ $ p \lor q$ $ p \land q$ $ p \veebar q$ $ p \rightarrow q$ $ p \leftrightarrow q$
F F F F F T T
F T T F T T F
T F T F T F F
T T T T F T T

For completeness, here are the remaining connectives, excluding trivial connectives which depend on only one or none of their arguments:

$ p$ $ q$ $ p \not\!\!\land q$ $ p \not\!\lor q$ $ p \leftarrow q$ $ p \not\rightarrow q$ $ p \not\!\leftarrow q$    
F F T T T F F    
F T T F F F T    
T F T F T T F    
T T F F T F F    



"truth table" is owned by rspuzio. [ full author list (2) | owner history (1) ]
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See Also: zeroth order logic

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Cross-references: arguments, expressions, conditional truth function, logical and, represents, rows, variables, connective, proposition, function, combinations
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This is version 11 of truth table, born on 2001-10-26, modified 2008-03-29.
Object id is 532, canonical name is TruthTable.
Accessed 22264 times total.

Classification:
AMS MSC03-00 (Mathematical logic and foundations :: General reference works )

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