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A '''boolean-valued function''', in some usages a '''predicate''' or a '''proposition''', is a function of the type <math>f : X \to \mathbb{B}</math>, where <math>X</math> is an arbitrary set, where <math>\mathbb{B}</math> is a generic 2-element set, typically <math>\mathbb{B} = \left \{ 0, 1 \right \}</math>, and where the latter is frequently interpreted for logical applications as <math>\mathbb{B} = \left \{ false, true \right \}</math>. | A '''boolean-valued function''', in some usages a '''predicate''' or a '''proposition''', is a function of the type <math>f : X \to \mathbb{B}</math>, where <math>X</math> is an arbitrary set, where <math>\mathbb{B}</math> is a generic 2-element set, typically <math>\mathbb{B} = \left \{ 0, 1 \right \}</math>, and where the latter is frequently interpreted for logical applications as <math>\mathbb{B} = \left \{ false, true \right \}</math>. | ||
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==References== | ==References== | ||
* ] (2003), ''Boolean Reasoning'', 1st edition, Kluwer Academic Publishers, Norwell, MA. 2nd edition, Dover Publications, Mineola, NY, 2003. | |||
* ] (1978), ''Switching and Finite Automata Theory'', 1st edition, McGraw–Hill, 1970. 2nd edition, McGraw–Hill, 1978. | * ] (1978), ''Switching and Finite Automata Theory'', 1st edition, McGraw–Hill, 1970. 2nd edition, McGraw–Hill, 1978. |
Revision as of 21:40, 28 June 2006
A boolean-valued function, in some usages a predicate or a proposition, is a function of the type , where is an arbitrary set, where is a generic 2-element set, typically , and where the latter is frequently interpreted for logical applications as .
In the formal sciences, mathematics, mathematical logic, statistics, and their applied disciplines, a boolean-valued function may also be referred to as a characteristic function, indicator function, predicate, or proposition. In all of these uses it is understood that the various terms refer to a mathematical object and not the corresponding semiotic sign or syntactic expression.
In formal semantic theories of truth, a truth predicate is a predicate on the sentences of a formal language, interpreted for logic, that formalizes the intuitive concept that is normally expressed by saying that a sentence is true. A truth predicate may have additional domains beyond the formal language domain, if that is what is required to determine a final truth value.
References
- Brown, Frank Markham (2003), Boolean Reasoning, 1st edition, Kluwer Academic Publishers, Norwell, MA. 2nd edition, Dover Publications, Mineola, NY, 2003.
- Kohavi, Zvi (1978), Switching and Finite Automata Theory, 1st edition, McGraw–Hill, 1970. 2nd edition, McGraw–Hill, 1978.
- Korfhage, Robert R. (1974), Discrete Computational Structures, Academic Press, New York, NY.
- Mathematical Society of Japan, Encyclopedic Dictionary of Mathematics, 2nd edition, 2 vols., Kiyosi Itô (ed.), MIT Press, Cambridge, MA, 1993. Cited as EDM (volume).
See also
Equivalent concepts
- Characteristic function
- Indicator function
- Predicate, in some senses.
- Proposition, in some senses.