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In fact computability can itself be defined via the lambda calculus: a function F: N → N of natural numbers is a computable function if and only if there exists a lambda expression f such that for every pair of x, y in N, F(x)=y if and only if f x = β y, where x and y are the Church numerals corresponding to x and y, respectively and = β ...
The names "lambda abstraction", "lambda function", and "lambda expression" refer to the notation of function abstraction in lambda calculus, where the usual function f (x) = M would be written (λx. M), and where M is an expression that uses x. Compare to the Python syntax of lambda x: M.
These functions may be defined in lambda calculus, or implemented in most functional programming languages (see converting lambda expressions to functions). The addition function plus ( m , n ) = m + n {\displaystyle \operatorname {plus} (m,n)=m+n} uses the identity f ∘ ( m + n ) ( x ) = f ∘ m ( f ∘ n ( x ) ) {\displaystyle f^{\circ ...
A function's identity is based on its implementation. A lambda calculus function (or term) is an implementation of a mathematical function. In the lambda calculus there are a number of combinators (implementations) that satisfy the mathematical definition of a fixed-point combinator.
The purpose of β-reduction is to calculate a value. A value in lambda calculus is a function. So β-reduction continues until the expression looks like a function abstraction. A lambda expression that cannot be reduced further, by either β-redex, or η-redex is in normal form. Note that alpha-conversion may convert functions.
Lambda expression may refer to: Lambda expression in computer programming, also called an anonymous function , is a defined function not bound to an identifier. Lambda expression in lambda calculus , a formal system in mathematical logic and computer science for expressing computation by way of variable binding and substitution.
Dirichlet lambda function, λ(s) = (1 – 2 −s)ζ(s) where ζ is the Riemann zeta function; Liouville function, λ(n) = (–1) Ω(n) Von Mangoldt function, Λ(n) = log p if n is a positive power of the prime p; Modular lambda function, λ(τ), a highly symmetric holomorphic function on the complex upper half-plane
This function can be used to achieve recursion. If β is the function that applies α to the self application of something else, β = Hα = S(Kα)(SII) then the self-application of this β is the fixed point of that α: SIIβ = ββ = α(ββ) = α(α(ββ)) = …