Boolean function

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In mathematics and logic, a Boolean function is a function whose arguments, as well as the function itself, assume values from a two-element set (usually {0,1}).[1] As a result, it is sometimes referred to as a "switching function".

A Boolean function takes the form f : {0, 1}k → {0, 1}, where {0, 1} is called a Boolean domain and k is a non-negative integer called the arity of the function. In the case where k = 0, the "function" is essentially a constant element of {0, 1}.

Every k-ary Boolean function can be expressed as a propositional formula in k variables x1, …, xk, and two propositional formulas are logically equivalent if and only if they express the same Boolean function. There are 22k k-ary functions for every k.

Boolean functions in applications

A Boolean function is one that can be utilized to evaluate any Boolean output in relation to its Boolean input by logical type of calculations. Such functions play a basic role in questions of complexity theory as well as the design of circuits and chips for digital computers. The properties of Boolean functions play a critical role in cryptography, particularly in the design of symmetric key algorithms (see substitution box).

Boolean functions are often represented by sentences in propositional logic, and sometimes as multivariate polynomials over GF(2), but more efficient representations are binary decision diagrams (BDD), negation normal forms, and propositional directed acyclic graphs (PDAG).

In cooperative game theory, monotone Boolean functions are called simple games (voting games); this notion is applied to solve problems in social choice theory.

In order to optimize electronic circuits, Boolean functions can be minimized using the Quine–McCluskey algorithm or Karnaugh map.

See also

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Further reading

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